Livre science anglais

Mathem

atics

Physics

Astronomy

1Working copy, October 2011

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Mathem

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Physics

Astronomy

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Table of contents

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PART I: THE CENTER AND THE INSTITUTION

Foreword 8Strategic intent 10Commitments 12

PART II: THE SCIENTIFIC AMBITIONS

PART III: THE CENTER IN GENEVA AND THE WORLD

Introduction

Theme 1From habitable worlds to the universe 20

Teaching and education 91

Theme 2Climate and atmospheric physics 34

National and inter-national relations, collaboration with other disciplines of the University of Geneva 95

Theme 3Quantum photonics and nanostructured devices for electronics 46

ScienScope 99

Theme 4Quantum materials 58

Laboratory of Advanced Technology 105

Theme 5From particles to the cosmos 68

Science library 113

Theme 6Mathematics 78

Services 117

PART IV: IN THE NEAR FUTURE

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PART I . The Center and the institution

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Foreword

I The Center and the institution

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As highlighted on the occasion of the Dies Academicus on its 450th anniversary, the founding of the Academy of Geneva is part of the mobilizing myth of the history of the Republic, bringing together enlightened faith, scientific labor, virtuous morals and exemplary institutions.

The epicenter of a truly international Huguenot constituency, since its foundation our University has welcomed a number of professors and students from all over Europe. This openness foreshadowed what has now come to be called the “Spirit of Geneva”, leading our city to the privileged position it holds, for many, in the world today.

Initially focused on theology and the Classics, our institution has increasingly opened up to other fields. This evolution allows it to embrace all disciplines today, from the humanities to the most fundamental physical sciences. This diversity through interdisciplinary approaches enables encounters and enriches exchanges.

The quest for rigor and excellence, combined with an earnest commitment to openness, remains at the root of our institu-tion’s successful governance policy.

Appearing within the top tier of polyvalent universities worldwide, our University, plays on its strengths as a globally renow-ned institution in its priority areas, most notably astronomy, physics and mathematics.

Looking to exploit this precious heritage while meeting the challenges of tomorrow, the center of excellence in astronomy, physics and mathematics will allow for the further enhancement of synergies between its disciplines. Moreover, it will tigh-ten our bonds with major international organizations based in Geneva such as CERN (the European Organization for Nuclear Research) and the WMO (United Nations World Meteorological Organization) and with other national and international actors.

With science, responsibility and collaboration as building blocks, our new Center is the perfect synthesis of the ambition of the University of Geneva for the future.

Professor Jean-Dominique Vassalli Rector University of Geneva

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Strategic intent


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The new Geneva Center for Astronomical, Physical and Mathematical Sciences will create conditions enabling our research teams to push the boundaries of our world and break new scientific grounds.

Our teams are internationally renowned for their work in fields as diverse as the search for the origins of the universe, the detection of extrasolar planets, quantum optics, the creation and study of new materials, high-energy particle physics, climate physics or the theory of percolation and tropical geometry.

The Center will bring together in a single project our geographically dispersed scientific forces. The interfaces created between the different departments and sections, clustered in themes, will favor the emergence of new research. In science, as in many other fields of human activity, sharing an interactive environment combines the energies from different fields, and optimizes the exchange and development of new ideas coming from interdisciplinarity.

This ambitious project is aligned with Geneva’s tradition of multidisciplinarity and cooperation between scientific, technological, economic and political institutions. It also takes into account, in substance and in form, the need to link research groups and industry closely.

Internationally, the Center will be an important destination, a focal point for researchers and students from around the world. It will also serve as a model for the organization and development of fundamental research of the XXIst century.

The building is conceived to inspire and stimulate creativity. It will optimize the resources and the spirit of its research teams by means of equipment, instruments and modular spaces suitable for academic exchanges.

Science has no boundaries. It is nourished by scientific networks. The consolidation of the individual expertise of our researchers into a critical mass will give rise to local networks and to an efficient participation in scientific research.

Our new Center will build upon an already very strong scientific base established by the individual researchers in Geneva. Combining their forces through this project, they are bound to creating a truly outstanding new research environment for astronomical, physical and mathematical sciences.

United, we make a difference.

Professor Øystein Fischer Director, NCCR MaNEP University of Geneva Project leader for the new Center

Strategic intent

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Commitments


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Professor Jean-Marc Triscone Dean, Faculty of Science University of Geneva

The broad diversity of existing in-house knowledge within the University of Geneva’s Faculty of Science is a unique ground for the efficient implementation of a new Center for astronomical, physical and mathematical sciences.

This initiative is a concrete answer to the necessity for transdisciplinarity in research and education. Such a contribution to collective intelligence fulfills the needs of future education by rejuvenating the art of formulating questions. Connecting the dots among research fields that have often been segregated will allow cross-fertilization, promoting excellence and promising the emergence of opportunities between disciplines.

Commitments

PROFESSORS AND ASSOCIATE PROFESSORS MEMBERS OF THE CENTER

Department of Astronomy

Prof. Thierry CourvoisierProf. Georges MeynetProf. Francesco PepeProf. Daniel PfennigerProf. Didier QuelozProf. Stéphane UdryProf. Daniel Schaerer

Physics section

Prof. Martin BenistonProf. Alain BlondelProf. Markus BüttikerProf. Allan ClarkProf. Ruth DurrerProf. Øystein FischerProf. Antoine GeorgesProf. Thierry GiamarchiProf. Nicolas GisinProf. Giuseppe IacobucciProf. Corinna Kollath

Section of Mathematics

Prof. Anton AlekseevProf. Martin GanderProf. Ernst HairerProf. Anders KarlssonProf. Marcos Mariño BeirasProf. Grigory MikhalkinProf. Stanislav SmirnovProf. Tatiana Smirnova-NagnibedaProf. András SzenesProf. Yvan Velenik

Prof. Michele MaggioreProf. Marcos Mariño BeirasProf. Alberto MorpurgoProf. Andreas MüllerProf. Marzio NessiProf. Patrycja ParuchProf. Martin PohlProf. Christoph RennerProf. Jean-Marc TrisconeProf. Dirk van der MarelProf. Jean-Pierre Wolf

PART II . The scientific ambitions

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II The scientific ambitions

Introduction

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The University of Geneva hosts many renowned researchers in the fields of astronomy, physics

and mathematics. These scientists position the University as a leading international research center,

particularly in the areas of exoplanets, quantum materials, quantum optics and mathematical physics.

Up to now, the many departments and sections have remained isolated from each other, scattered

throughout Geneva. Bringing leading researchers together in one building in a unique environment

aims not only to reinforce our key fields of focus, but also and foremost to create synergies and

stimulate collaborations among the scientists in Geneva.

Meetings between all the research groups organized to establish the building blocks of the Center,

have uncovered the huge potential for future scientific developments by bringing the different

scientific domains spatially closer to each other.

The resulting scientific project fed by such a spirit revolves around six key themes on which

researchers from different sections and departments can collaborate, making important new

contributions to their fields.

This innovative, pluridisciplinary approach to research creates an atmosphere of scientific

coherence in the University, significantly strengthening research, the teaching of science and

opening new opportunities for our students.

Introduction

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The discovery of new planets beyond our solar system, in particular the detection and characterization of other habitable planets similar to Earth, is a fascinating intellectual adventure. It is one of the major scientifi c, technological and philosophical endeavors of our time. It unavoidably leads us to reassess our views on the origin of our own planet, our place in the cosmos, and the possibility of fi nding life elsewhere in the universe, with probable profound social implications. Research in the fi eld of exoplanets has therefore been naturally recognized as a priority domain by all the main research agencies worldwide (European Space Agency – ESA, National Aeronautics and Space Administration – NASA, European Southern Observatory – ESO, etc.), and integrated in their development plans for the next decade and more. To be successful in this quest researchers have to imagine original and effi cient observing strategies to detect new planetary systems, to deduce their properties and characterize their atmospheres through adequate cutting-edge technological and instrumental developments.

The level of knowledge that can be gained on extrasolar planets is intrinsically connected to the information available about their environment, and principally their host stars. Stellar physics is crucial in improving the planet detection process, as most of the detection methods provide planetary physical parameters as a function of those of the star. Our knowledge of the star, through accurate observations and state-of–the-art stellar evolutionary models, is thus a key prerequisite in the determination of planet characteristics. On another scale, stars are the engines of galaxies, driving many evolutionary processes, such as their photometric and chemical evolutions. Stellar evolution models offer a fantastic tool for exploring many topical questions ranging from the determination of the mass, radius and age of planet-host stars to the nature of gamma-ray burst progenitors, passing through the source of the ionizing photons in the early universe and the nature of the very fi rst stars.

ThEmE 1.From habitable worlds to the universe

Participants in this theme (status 2011):Georges Meynet, Francesco Pepe, Daniel Pfenniger, Didier Queloz, Daniel Schaerer, Stéphane Udry

II The scientifi c ambitions

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Bright blue newly formed stars blowing a cavity in the center of a fascinating star-forming region known as N90. (Credit: NASA, ESA and the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration and Astronomy and Astrophysics (Meynet & Maeder 2002, A&A 390, 561))


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1. TheroadtothediscoveryofnewEarthsintheuniverse

For a very long time, the solar system was the only known example of a planetary system, driving scientifi c views and knowledge of the fi eld, from planet formation to the characterization of life. This drastically changed with the discovery of the fi rst giant gaseous planet orbiting a star similar to the sun by two astronomers from the University of Geneva (Mayor, Queloz) in 1995. The subsequent wealth of discoveries of more than 500 planetary candidates over the next 16 years has demonstrated that planets are common around other stars and that their properties are much more diverse than originally foreseen. The most remarkable overarching feature of the sample of known planets is undoubtedly the variety of orbital characteristics, largely unexpected from the observation of the Earth’s solar system, and challenging our standard paradigm of planetary formation. Planets are common and planetary formation processes produce a surprising variety of confi gurations: masses considerably larger than Jupiter, planets moving on highly eccentric orbits, planets in resonant multi-planet systems, and planets orbiting components of stellar binaries. Understanding the physical reasons for such wide variations in outcome remains a central issue in planet-formation theory.

Exoplanets in GenevaAnswers to the questions raised by the new discoveries will certainly benefi t from constraints provided by the distribution of planetary properties observed in the different search programs conducted by Geneva planet hunters. The radial velocity method used in most of those surveys, unveiling the planet by its induced perturbation on star motion, allows for the determination of planet orbital parameters and of a lower limit of the planet mass. Most of the detected planets are massive gaseous giants similar in nature to Jupiter. The past few years have, however, seen a new breakthrough in the domain with the detections of light (4-20 Earth masses), solid (rocky/icy) planets (Mayor, Pepe, Queloz, Udry). The low-mass planet detections were made possible thanks to the development of new stable and more precise instruments for radial-velocity measurements, such as the European Southern Observatory’s High Accuracy Radial-velocity Planet Searcher (HARPS) spectrograph designed for high-precision planet search and developed by a consortium led by Geneva astrophysicists (Mayor, Pepe). Since 1995, the exoplanet team of the Astronomy Department of the University of Geneva (Mayor, Pepe, Queloz, Udry) has occupied an exceptional position in the fi eld, leading the detection of extrasolar planets with about half of the detections of the planets known to date, including the majority of the smaller mass super-Earths and Neptune-mass planets. Present results

Galaxies are the locations in the universe where most stars form. Since they confi ne gas and stars by gravity, galaxies allow the recycling of the elements processed and ejected by successive generations of stars. Therefore, they play an important role in understanding the origin of planets and of most of the matter from which humans are made throughout the history of the universe. Humans are a lump of a particular galaxy, the Milky Way. Galaxies are understood today as evolving and dynamical structures with very challenging and multidisciplinary physics and chemistry problems. Unveiling what happened when the fi rst galaxies appeared in the universe is the focus of many important observing programs using the largest facilities available today.

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suggest that the already published discoveries only represent the tip of the iceberg, and that a new population of Neptune-mass and super-Earth planets, not existing in our solar system, is emerging around 30% to 50% of the stars like our Sun. Among other important results obtained within the different programs conducted in Geneva are the detections of the first planet on a counter rotating orbit, and the first and only known super-Earth in the habitable zone of the low-mass star Gl581.

Studies conducted in the field of exoplanets aim principally at a better understanding of their formation and evolution, as well as at improving knowledge of the internal structure and atmospheres of these systems, from gaseous to rocky planets. Tight constraints for planet models are obtained by the observations of a photometric transit, an eclipse of the star by the planet. Combined with velocity measurements, such observations yield the precise mass, radius and mean density of the planet, providing priceless constraints on its internal structure. Important results have already been obtained with this combined approach (Mayor, Pepe, Queloz, Udry), such as the characterization of CoRoT-7b, the first confirmed rocky planet, which presents a density close to that of the Earth.

From the first detections, the Geneva activities in the exoplanet domain have developed, growing in diversity. The main lines of research now include the astrometric detection of exoplanets (Pepe, Queloz), the detection and characterization of transiting planets (Pepe, Queloz, Udry) from the ground (SWASP - Super Wide Angle Search for Planets, the UK’s leading extra-solar planet detection program) and in space (Corot/ESA, Kepler/NASA), and high-contrast imaging of substellar brown dwarfs and massive planets (Udry). The ensemble is coupled through a related, large and coherent program of instrumental development for ground-based observations (PRIMA - Phase-Referenced Imaging and Microarcsecond Astrometry, SPHERE Spectro-Polarimetric High-contrast Exoplanet REsearch, ESPRESSO - Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations,

Artistic view of an extra-solar planetary system hosting an Earth-like planet in the habitable zone of the system, and inner planets similar to the ones detected by present radial-velocity surveys. (Credit: European Southern Observatory - ESO)

HARPS-NORTH - High Accuracy Radial-velocity Planet Searcher, etc.; Pepe, Queloz, Udry), as well as an active participation in future space missions (Gaia/European Space Agency (ESA), CHEOPS/Switzerland, PLATO/ESA; Mayor, Pepe, Queloz, Udry). Many questions remain unanswered, however, and efforts will be pursued in the direction of the detection and characterization of exoplanets of all types and in various environments focusing on low-mass planets, possibly in the habitable zone around their star.

Prospects in the domain of exoplanetsIn the long term, the results obtained will represent only a first step towards the much more ambitious goal of finding life outside the solar system. To reach this point, two major challenges in the field have to be solved: first to detect planets similar to the Earth (i.e., rocky and in the habitable zone of the star), and second to directly image planets close to their stars, and thus have direct access to the composition of their atmosphere and search for


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biotracers. These ambitious lines of research are already in the background of most of the projects conducted by the exoplanet group in the Astronomy Department of the University of Geneva.

Instrumental developmentOver the past decade Geneva astronomers have been leading the development of new instrumentation aimed at eventually fi nding these objects outside the solar system. Several of these efforts (HARPS-NORTH, PRIMA, SPHERE) will bear fruit in the coming few years, providing exciting new discoveries. While capitalizing on past efforts, Geneva astronomers are also preparing for the future by participating in or proposing the development, and subsequently the operation, of a coherent set of ground- (NGTS - Next Generation Transit Surveys, ESPRESSO) and space-based instruments (PLATO - PLAnetary Transits and Oscillations of stars, CHEOPS - CH (Swiss) ExOPlanet Satellite), including a new generation of high-resolution spectrographs or

Planet atmosphere and habitability While the detection of Earth-like planets is in itself a momentous achievement, these efforts have yet an additional justifi cation: they help the understanding of the formation of planetary systems in general, including the Earth’s own solar system, in particular the Earth and its ability to sustain life. The habitability of planets will be addressed by combining results from the theoretical modeling (interior/atmosphere/climate) and the actual spectroscopic observations of planetary atmospheres, activities to be developed in Geneva through synergies with local groups in the context of the new Center, or at the Swiss level through collaborative initiatives. While measuring the spectrum of an exoplanet is still beyond our instrumental capabilities, the advent of larger aperture, ground-based telescopes (E-ELT for example) and space facilities (James Webb Space Telescope – JWST) will change this situation. In preparation for this, the Center aims to develop expertise in astrophysical radiative transfer processes, focusing in particular on observational planet spectroscopy, with the goal of designing and conducting leading observational campaigns with present and future facilities.

A center for exoplanet studiesConsidered not very long ago by most as a wild dream, the search for and study of Earth-like planets outside the solar system will become reality within the next decade. At a time when the required knowledge and technology are being defi ned worldwide,

specialized telescopes for the search of transiting planets down to Earth-like planets. Major developments must take place within the context of international collaborations, in particular with ESO for ground-based telescopic instrumentation and with ESA for space-based activities. Technological developments are cast with these collaborations in mind and the activities proposed either fi t within their programs or are complementary to them. For Switzerland, a mini-satellite (CHEOPS) project will also serve as an incubator program for the development of space-related science and technology and a test for a national program.

The PLATO/ESA next generation planetary system explorer. The scientifi c goal of the mission is to detect and characterize transiting exoplane-tary systems, especially small telluric planets in the habitable zone of their stars. (Credit: Mark A. Garlick. Science Credit: Carole Haswell & Andrew Norton (The Open University) with

support from UKSpA)


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Geneva can place itself at the forefront of this remarkable quest by capitalizing on pioneering work as well as on synergies at the local, national and international levels. The question of the habitability of the new worlds detected cannot be answered by a single community. As already pointed out, the detection of true Earth twins is very challenging. It requires the development of next generation instrumentation with the expertise of mechanical, electrical or laser engineers. The interpretation of the observed planet properties (for example, mass and radius) involves internal structure models developed by geologists and planetary scientists. Atmosphere characterization involves results from observations coupled with interior, atmosphere, and climate models. In the context of the new Center, a coherent effort in this direction is already starting with the project of a platform allowing researchers of different fields to join in this enthusiastic and most challenging endeavor. Geneva astronomers have been at the forefront of the search and study of planets outside the solar system, they have been instrumental in many ground- and space-based experiments, and they have been developing unique technology. The goal of this proposal is to maximize the benefits of this existing world-class know-how in astronomy and high-tech optical and mechanical systems by building up a multi-disciplinary center of competence for the search, characterization, and study of planetary systems and their suitability to sustain life. Such an integrated effort, and the large added value it generates, is needed to make further scientific progress in this field. The vision is to continue to ensure a long-term leading role for Geneva scientists in this domain.

2. Starsforstudyingplanets,galaxies,andphysics

Stars are key objects for understanding our universe at all scales: they are the sources of the elements constituting our planet and its inhabitants; the knowledge of the evolution of our star, the Sun, is essential to understand long-term climatic changes; they are fundamental standard candles to measure distances in the cosmos; they allow for the measurement of the age of stellar clusters; they contribute to driving the evolution of galaxies. Stars can be used to probe the behavior of elementary particles such as neutrinos, and to explore fundamental aspects in physical theories. Stellar physics is therefore at the heart of many topical subjects addressing questions ranging from the evolution of the universe at large scale, down do that of matter at the scale of elementary particles.

Artistic view of the future 40-m European Extremely Large Telescope to be installed on Cerro Armazones (Chile). (Credit: European Southern Observatory - ESO)


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Upper left corner: stream lines of meridional circulation in a rotating 20 solar mass model with solar metallicity and an initial rotation at the equator of 300 km s-1 at the beginning of the H-burning phase. (Credit: NASA, ESA and the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration and Astronomy and Astrophysics -Meynet & Maeder 2002, A&A 390, 561)

Stellar physics in GenevaAstrophysicists at the Department of Astronomy of the University of Geneva are conducting ambitious observational and theoretical projects in stellar physics. Spectral information from the whole spectrum, from infrared to X-rays, is collected for star forming regions. A strong observational effort is also dedicated to the study of stellar variability, a property that is crucial to probing the interior of stars and precisely determining their physical properties, as well as for measuring distances in the universe. The theoretical stellar evolution modelers are at the forefront of research in their fi eld. Geneva stellar models have been successful in proposing explanations for longstanding problems, such as the internal rotation profi le of the Sun, the production of primary nitrogen in the early galaxy (Maeder, Meynet), the galactic evolution of primordial elements produced during the Big Bang, etc. They are also heavily used as input ingredients for studying the photometric evolution of galaxies.

Prospects in stellar astrophysics

The Stellar Physics group is in the best position to provide new observational constraints for stellar formation and evolution models, as well as for building the most reliable theoretical predictions for the internal structure, evolution, lifetimes, nucleosynthesis, and the ultimate fate of individual stars. In the next decade, the aim is to develop synergies with colleagues studying extrasolar planets, galaxies, deep universe and dark matter, in order to propose new and original views on the interactions between star and planets, star and galaxies, and stars and the cosmos.

Star-planet connections - Star and planet formation provide clues to the origin of our solar system. Researchers at the Department of Astronomy are already involved in observational studies of young stars via multiwavelength (millimeter, infrared and X-ray) telescopes and satellites to tackle the connections between star and planet formation. Upcoming and future observing facilities (Atacama Large Millimeter Array - ALMA, E-ELT, SPICA - Space Infrared Telescope for Cosmology & Astrophysics) promise excellent advances, for example at high spatial resolution in protoplanetary disks, or for sensitive observations of gas in young disks. Stellar physics is crucial for improving the planet detection process as well as for the determination of key properties of star-planet and planetary systems. Theoretical studies will explore the possibilities to fi nd signatures of the presence of terrestrial planets in the rotation rates or in the surface abundances of stars, or study the interactions between protoplanetary disks and forming stars. To address these questions, hydrodynamical models linking the evolution of central stars, their protoplanetary disks, and planetary systems have to be developed taking into account all possible hydro- and magneto-hydrodynamical interactions. This theoretical approach will greatly benefi t from asteroseismology to gain insights into the internal structure of planet-host stars, as well as from interferometry to reveal the geometry of the disks and of the polar ejections during the formation process. Such investigations will contribute to

.IIIV.noitatorhtiwnoituloveralletS:redeaM.AdnatenyeM.G265

Fig. 1. Stream lines of meridional circulation in a rotating 20M model with solar metallicity andvini = 300 km s−1 at the beginning ofthe H–burning phase (see text). The streamlines are in the meridian plane. In the upper hemisphere on the right section, matter is turningcounterclockwise along the outer stream line and clockwise along the inner one. The outer sphere is the star surface and has a radius equal to5.2 R . The inner sphere is the outer boundary of the convective core. It has a radius of 1.7R .

The evolution of surface abundances are examined in Sect. 7.In Sect. 8, we discuss the problem of the origin of primary ni-trogen and we show how rotation can solve it. The chemicalyields in He, CNO and heavy elements are discussed in Sect. 9.

2. Physics of the models

The initial composition is given in Table 1. The compositionis enhanced in α –elements. As in Paper VII, the opaci-ties are from Iglesias & Rogers (1996), complemented at

low temperatures with the molecular opacities of Alexander(http://web.physics.twsu.edu/alex/wwwdra.htm ). Thenuclear reaction rates are also the same as in Paper VII and arebased on the new NACRE data basis (Angulo et al. 1999).

The physics of the present models atZ = 10−5 is the sameas for models atZ = 0.004 (Maeder & Meynet 2001). For ro-tation, the hydrostatic e� ects and the surface distortion are in-cluded (Meynet & Maeder 1997), so that theTe� given herecorresponds to an average orientation angle. The di� usion byshears, which is the main e� ect for the mixing of chemical


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understanding our near scale cosmic home, the solar system, and more generally the star formation process and the large variety of planetary systems.

Star-galaxies interactions - Stellar formation, evolution and death are qualitatively known to affect the interstellar environment and to impact on the dynamical and chemical evolution of galaxies from the early stages. Geneva stellar physicists have already proposed new and original ideas concerning the impact of the first stellar generations on the early evolution of star clusters and galaxies. In the future they plan to tackle key interface questions quantitatively. Among them is the importance of stellar evolution feedback on the gas content of galaxies and on the degree of turbulence in the interstellar medium, quantities that in turn regulate star formation on galactic scales. They also plan to study dynamical aspects related to the mixing timescale of new chemical elements synthesized and injected by stars within the interstellar medium, and the driving of galactic winds that participate in the chemical evolution of the intra-cluster medium. Other aspects will be investigated, such as the nature of the sources that reionized the early universe, the contribution of massive star clusters to field stellar populations of the halo and disks of galaxies, the photometric and chemical evolution of different types of galaxies along the whole cosmic history, or the evolution of the rates of different types of stellar explosions (supernovae, gamma ray bursts) at the cosmic level. Such exploratory work will provide new quantitative predictions for many features that will be tested using the largest telescopes to be built during the next decade, such as the E-ELT, JWST or ALMA. The star-physics connection - Stars are extraordinary and unique laboratories for all domains of fundamental physics. They are sufficiently massive for gravity to play a key role and sufficiently dense for interactions between electromagnetic radiation and matter to happen. These magneto-hydrodynamical objects host nuclear reactions and emit neutrinos. They produce most of the chemical elements that make up the universe, its planets, and life

building blocks. Stars end their life as the densest objects known in the universe (white dwarfs and neutron stars), and may also give birth to black holes and gamma ray bursts, which are, along with supernova explosions, the most energetic events observed to date. It is now widely accepted that the art of modeling stars (from their formation to their death) in the XXIst century will strongly rely on the ability to identify, understand and describe the various and complex hydrodynamical and magneto-hydrodynamical mechanisms (rotation, atomic diffusion, magnetic fields, internal gravity waves, salt-finger instabilities, matter accretion, mass loss, etc.) that contribute to the transport of chemicals and angular momentum in stars at different phases of their evolution. Some of these processes are also present on Earth, either in the atmosphere, in the oceans, or in the laboratories, which makes stellar physics more than ever a pluridisciplinary science. Important progress is expected in the future from interactions with specialists in these domains, in particular thanks to fast developing multi-dimensional hydrodynamical simulations. The present sophistication of stellar theory also allows scientists to explore theories beyond standard physics, like the variations with time of physical constants, the multi-dimensionality of space-time universe, the physics of gravitational waves, and the nature of dark matter, among others. This domain of application of stellar physics is relatively young but extremely promising as it opens new and broad research areas at the interface between astrophysics and theoretical physics, as shown by exploratory work done by the group.


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3. FromtheMilkyWaytothedistantuniverse

The origin of complexity in the universe starts during the fi rst billion years after the Big-Bang when gravitational instability deploys its anti-classical thermodynamics properties, due to the unscreened long range of gravity. Instead of tending toward uniform equilibrium states, gravitating matter exacerbates minute inhomogeneities by amplifying density and temperature gradients over tens of powers of ten. This leads to the formation of all astrophysical structures, which range through a very wide breadth of physical conditions, from the fi rst stars and galaxies to black holes or intergalactic voids. Keeping a large temperature difference between a star’s hot surface (~6,000K) and the coldness of the universe (~3K) for billions of years is a key condition for the emergence of life at an intermediate temperature (~300K).Exploring the universe and its constituents, back to the very fi rst moments after the Big Bang, is one of the main frontiers of observational astronomy. Spectacular breakthroughs have been made during the last decade. Thanks to the Hubble Space Telescope (HST) and to 8m class telescopes such as the European Very Large Telescope (VLT), astronomers are on the verge of studying the most distant galaxies, and discovering the very fi rst ones. Such observational breakthroughs and other theoretical advances make cosmology one of the most exciting fi elds of science. Enormous progress in cosmological structure formation models, detailed hydrodynamical simulations at various scales, and observations of the intergalactic medium, galaxies and stars, have provided a new global picture of the universe as a dynamic, evolving and interconnected web where exchanges of radiation, energy and matter between different physical objects over vast spatial scales play a crucial role. In many domains of astrophysics this has drastically modifi ed scientifi c understanding of phenomena in the cosmos. One of the consequences of this recent picture is that the still poorly understood “feedback” effects on baryonic matter from stars and supernovae have been recognized as fundamental for the understanding of dark matter and the formation of structures in the universe.

Galaxies in Geneva - A journey through space and time

The physics of galaxies in Geneva is addressed by two complementary approaches: fi rst through models of the dynamics and physics of galaxies (Pfenniger) and second, by the detection and modeling of the most distant galaxies in the universe (Schaerer).

Galactic dynamicists are studying the dynamical evolution of galaxies (Pfenniger), relying on the wealth of data available for nearby galaxies. They concentrate fi rst on dynamics, considering that gravity and bulk motion are the basic physical ingredients explaining galaxies over several tens of rotational periods. Gravity induces non-trivial collective behavior because of its long range. Galaxies must be understood as dynamical objects, still evolving today in a so-called “secular” evolution phase, i.e., a slow post-collapse evolution mainly determined by its dissipative internal physics, and less and less by the cosmological initial conditions. Galactic disks are prone to spontaneously breaking their symmetries by making bars, spirals and warps. In such disks several feedback mechanisms operate and set specifi c global properties. Most galaxies contain a large black hole at the center, and its impact on the galaxy and its surroundings is non-negligible in view of the large energy output needed just to allow the condensation of the black hole mass. The nature and amount of dark matter in galaxies are still uncertain. Recently, however, much more cold “dark” gas has been found in the Milky Way disk, in particular by the ESA Planck satellite. This confi rms in part the proposition (Pfenniger) that a large amount of cold baryons can still hide in galaxies like the Milky Way.

The exploration of the distant and early universe is a multi-disciplinary/multi-faceted domain of contemporary astrophysics relying extensively on multi-wavelength observations, cutting-edge theoretical developments and state-of-the-art simulations. Geneva astrophysicists are strongly engaged in a variety of projects. One of the main observational quests is the direct observation of the fi rst galaxies and stars in the universe (Schaerer), including in particular so-called Population III stars formed from pristine matter shortly after the Big Bang. From halo


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stars to distant galaxies, searches for this enigmatic population have already started. New strategies are being elaborated, especially in the perspective of future missions like the JWST and the E-ELT. Geneva astronomers are strongly involved in such observational projects, also as leaders for the spectral modeling of Population III. They are also exploiting strong gravitational lensing to study the faintest objects in the universe (Schaerer). They are among the world’s leaders in various modeling techniques, such as radiation transfer and spectral models. Related to searches of the first galaxies is the study of cosmic reionization, the second important cosmological period during which the gas of the universe underwent a phase change. When the first stars and galaxies formed they ended the so-called dark ages, starting a transition period lasting approximately up to 1 billion years (z~6) after the Big Bang. Geneva astronomers are already actively engaged in such observations using in particular the Hubble and Spitzer space telescopes, and the VLT.

Future prospects in galaxies and cosmologyOne major objective for the next decade and beyond is to write the complete history of the formation and evolution of gas, chemical elements, dust, stars, black holes and galaxies during the entire life of the universe, from the Big Bang to the present day. This ambitious goal involves numerous and diverse observations of galaxies and the intergalactic medium, as well as complex improved simulations to guide interpretation and to be tested against observations. Future multi-wavelength surveys using upcoming facilities with greatly improved sensitivity, spatial resolution, and spectral coverage will allow scientists to write new pages of cosmic history. Despite impressive advances, many questions remain, and new unknown territories, both observational and theoretical, are waiting to be explored.

Galaxy modeling - The precise reasons why galaxies exist, and have typical sizes and properties, are still poorly understood. Galaxies are self-regulating dissipative structures attracted toward a subset of possible conditions. The challenge in the

next decades will be to better describe the several feedback mechanisms at play. Up to now much effort has been dedicated to explaining the galaxy scale by the cosmological initial conditions leading to gravitational instabilities, merging and collisions of galaxies, with a substantial fraction of non-baryonic dark matter required to quickly drag the usual matter into potential wells. The cooling properties of intergalactic gas are also seen as crucial to determining the galaxy scale in the initial conditions of gravitational contraction. However, the actual properties of galaxies, such as the high fraction of disks and bulgeless disks, are not reproduced by these hypotheses. Something important is missing.

The distant universe - A large part of scientific understanding of the cosmos and its structure comes from the study of galaxies and of the intergalactic medium at very high redshift. This study provides researchers not only with a history of galaxies, their gas, and their early stars, but allows for the study of the interplay between the different constituents of the universe. This exploration will continue. Theoretical efforts have to be anchored in the recent observational results obtained with the Planck mission, and in the future with EUCLID, the E-ELT, ALMA, and JWST. Although simulations have been developed to describe cosmic reionization, many theoretical and observational questions remain. For example, what is the reionization history of the universe, and what is the dominant reionization source? While the deepest observations of the cosmos with the largest telescopes are starting to scratch the surface of these problems, breakthroughs are expected from the JWST and ELTs operating in this field. The importance of exploring the distant universe has been underlined by essentially all international science planning panels, for example in the ASTRONET European Infrastructure Roadmap, ESA’s Cosmic Vision, and in the E-ELT Science Cases. Major investments have been made and are foreseen in next-generation instruments, satellites and major European and intercontinental facilities specifically designed for the exploration of the distant universe.


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New numerical methods - Due to the complex content of the universe and to the new windows opening on objects at cosmic distances, astronomy is largely data driven. Theory and computer modeling are furthermore indispensable complementary approaches to observation. Galaxies are certainly complex and include numerous, non-linear processes covering almost all the domains of physics and chemistry over tens of orders of magnitudes in scale. Computerized galaxy models will thus become more and more complex, and will require the formation of teams that bring together experts in astrophysics, numerical mathematics, computer science programming, and data visualization. Synergies between astrophysics and computational sciences will become increasingly important. The new Center will certainly offer a fertile crucible in this context.

4. Conclusion

Astrophysicists at the University of Geneva are among the world’s leaders in the different fi elds participating in collectively understanding the universe as a whole, from the planets to the cosmos, from close neighborhoods to the far reaches of the universe. They are actively involved in ambitious projects at the theoretical, observational and instrumental level. They benefi t from these projects, not only from the expectedly spectacular scientifi c results, but also from the expertise gained during project development and operation. This is especially important for young researchers in the context of new large facilities (such as the European Extremely Large Telescope (E-ELT) and associated instrumentation, future satellites, etc.) planned by leading European agencies. Developing these activities in the context of the Center will undoubtedly be benefi cial, taking advantage of locally available expertise and synergies.


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SelectedpublicationsbyGenevaresearchers

1. Charbonnel, C., S. Talon, 2005: “Influence of Gravity Waves on the Internal Rotation and Li Abundance of Solar-Type Stars”, Science 309, Issue 5744, pp. 2189.

2. Chiappini, C., U. Frischknecht, G. Meynet, R. Hirschi, B. Barbuy, M. Pignatari, T. Decressin, A. Maeder, 2011: “Imprints of fast-rotating massive stars in the Galactic Bulge”, Nature 472, 454.

3. Eggenberger, P., A. Maeder, G. Meynet, 2010: “Effects of rotation and magnetic fields on the lithium abundance and asteroseismic properties of exoplanet-host stars”, Astronomy & Astrophysics 519, pp. L2.

4. Lovis, C., D. Ségransan, M. Mayor, S. Udry, W. Benz, J.-L. Bertaux, F. Bouchy, A.C. Correia, J. Laskar, G. Lo Curto, C. Mordasini, F. Pepe, D. Queloz, N. C. Santos, 2011: “The HARPS search for southern extra-solar planets. XXVIII. Up to seven planets orbiting HD 10180: probing the architecture of low-mass planetary systems”, Astronomy & Astrophysics 528, A112.

5. Maeder, A., G. Meynet, 2005: “Stellar evolution with rotation and magnetic fields. III. The interplay of circulation and dynamo”, Astronomy & Astrophysics 440, 1041.

6. Mayor, M., D. Queloz, 1995: “A Jupiter-mass companion to a solar-type star”, Nature 378, 355.

7. Mayor, M., S. Udry, C. Lovis, F. Pepe, D. Queloz, W. Benz, J.-L. Bertaux, F. Bouchy, C. Mordasini, D. Segransan, 2009 : “The HARPS search for southern extra-solar planets. XIII. A planetary system with 3 super-Earths (4.2, 6.9, and 9.2 M⊕)”, Astronomy & Astrophysics 493, 639.

8. Meynet, G., A. Maeder, 2002: “The origin of primary nitrogen in galaxies”, Astronomy & Astrophysics 381, pp. L25.

9. Pfenniger, D., C. Norman, 1990: “Dissipation in barred galaxies - The growth of bulges and central mass concentrations”, Astrophysical Journal 363, 391.

10. Pfenniger, D., F. Combes, L. Martinet, 1994: “Is dark matter in spiral galaxies cold gas? I. Observational constraints and dynamical clues about galaxy evolution”, Astronomy & Astrophysics 285, 79.

11. Pfenniger, D., F. Combes, 1994: “Is dark matter in spiral galaxies cold gas? II. Fractal models and star non-formation”, Astronomy & Astrophysics 285, 94.

12. Queloz, D., F. Bouchy, C. Moutou, A. Hatzes, G. Hébrard, and 35 coauthors (including M. Mayor, F. Pepe, S. Udry), 2009: “The CoRoT-7 planetary system: two orbiting super-Earths”, Astronomy & Astrophysics 506, 303.

13. Richard, J., R. Pelló, D. Schaerer, J.-F. Le Borgne, J.-P. Kneib, 2006: “Constraining the population of 6 ≤ {z} ≤ 10 star-forming galaxies with deep near-IR images of lensing clusters”, Astronomy & Astrophysics 456, 861.

14. Schaerer, D., 2002: “On the properties of massive Population III stars and metal-free stellar populations”, Astronomy & Astrophysics 382, 28.

15. Schaerer, D., S. de Barros, 2010: “On the physical properties of z ≈ 6-8 galaxies”, Astronomy & Astrophysics 515, A73.

16. Udry, S., N.C. Santos, 2007 : “Statistical Properties of Exoplanets”, Annual Review of Astronomy & Astrophysics 45, 397.

17. Udry, S., X. Bonfils, X. Delfosse, T. Forveille, M. Mayor, C. Perrier, F. Bouchy, C. Lovis, F. Pepe, D. Queloz, J.-L. Bertaux, 2007: “The HARPS search for southern extra-solar planets. XI. Super-Earths (5 and 8 M⊕) in a 3-planet system”, Astronomy & Astrophysics 469, L43.


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Understanding the atmosphere and climate requires investigations that span a large range of spatio-temporal scales, from the nanometric scales related to cloud condensation droplets and the thermodynamic processes that are associated, to phase changes of water, to the quasi-planetary scales of long-range weather evolution and climatic change. There is not one single paradigm that enables the study of atmospheric processes simultaneously at all scales; it is thus necessary to use advanced experimental and modeling techniques to focus on various spatial and time scales separately, while at the same time attempting to fi nd an interface between each successive scale in order to retain as far as possible a continuum of scales and the processes that are embedded therein. The following pages address themes, processes, and scales that are at fi rst glance very different from one another, but that are in fact subtly coupled. It is this coupling through different approaches that makes the focus of this theme particularly unique.

ThEmE 2.Climate and atmospheric physics

Participants in this theme (status 2011):Martin Beniston, Martin Gander, Jean-Pierre Wolf


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Global warming projections by 2100 (compared to 2000), as climate responds to increased greenhouse gas concentrations in the atmosphere; the heteroge-neous nature of warming is one sign of the non-linear nature of the system as it responds to a perturbation. (Credit: IPCC, 2007: Climate Change, the 4th Assessment Report

of the Intergovernmental Panel on Climate Change)

1. Climatedynamicsandbifurcations

Over the past two decades, issues related to climate and climatic changes have come to the forefront of scientifi c, environmental, media, public and political attention. One of the reasons for this high level of interest, beyond the implications of a changing climate for the global economy and natural resources, is related to the success of climate system computer simulations and the temperature and precipitation projections of future trends. Indeed, computer simulations of climate have been instrumental in forging policy (for example, the Kyoto Protocol and other follow-up agreements) and represent a rare example of effi cient information fl ow from science to decision-making.Some of the signifi cant developments in atmospheric and climate research have been to pioneer some of the early Swiss work on regional climate modeling and the application of numerical techniques to understand the functioning mechanisms

underlying extreme climatic events (those that have the most signifi cant impacts in terms of human life and economic costs) and their possible evolution in a warmer global climate in the course of the XXIst century. A further set of successes has been the integration of numerous additional disciplines that are relevant to understanding why climate physics is being perturbed by human activities, and why a changing climate can signifi cantly impact numerous elements of the physical, biological, economic and social environments. Bridging the gap between different disciplines is a challenge in conceptual terms, but also provides signifi cant added value for many climate-related studies at both the theoretical and the experimental levels.

Despite these achievements, however, the ability to predict the evolution of the climate system with models remains limited because of

• limited spatial and temporal resolution related to available computer resources;

• sparse observations of the Earth system, where data for model validation are not always available;

• insuffi cient understanding of multiple, non-linear interactions between elements of the climate system, i.e., the oceans, the cryosphere and the biosphere.

Furthermore, in the early 1960s Edward Lorenz at MIT demonstrated that the essential non-linearity of the climate system makes numerical predictions diffi cult because of the dependency of model solutions on initial and boundary conditions that, as mentioned above, are often sparse in space and/or time.

While today’s climate models inherently integrate the chaotic element of the system into the set of non-linear equations that govern climate physics, there has been relatively little exploration of the behavior of climate and the potential for large disruptions to the system as it approaches a more chaotic regime. Indeed, there are likely to be a number of bifurcation points (or “tipping points”) in the system, beyond which climate may enter into a


37

Changes in discharge in the Rhone River in Switzerland in a changing climate.The increase in wintertime fl ows is related to increases in rainfall, the strong decreases in summer are linked to drier conditions and the quasi-disappearance of snow and ice in the Alps that today supply water during the warmest part of the year. (Credit: Beniston, M., 2010: Journal of Hydrology)


new state with wide-reaching implications for our planet and human societies.Causes for rapid changes in climate include:

• instabilities in ocean-atmosphere coupling, as would result from a breakdown of the North Atlantic surface circulations and the North Atlantic Deep Water formation in the Greenland-Iceland sector;

• rapid shifts in albedo-climate feedback associated with a signifi cant reduction of sea-ice in the Arctic Ocean resulting from current atmospheric warming trends;

• reductions in the transfer of moisture from soil to atmosphere consecutive to major land-use changes, such as urbanization or deforestation, which modify the natural texture of the surface;

• disruptions to the “ocean carbon pump” (i.e., the infl uence of photosynthetically active organisms in the ocean that are capable of absorbing atmospheric carbon dioxide) resulting from ocean acidifi cation, and that in time reduce carbon uptake from the atmosphere and thus enhance the “greenhouse effect”;

• melting permafrost in the Arctic region that releases organic carbon stored in currently frozen grounds, thus producing a pulse of methane and carbon dioxide into the atmosphere and a rapid increase in the radiative forcing of climate;

• effects of quasi-periodic oscillations of climate on annual-to-decadal timescales that can be cumulative or not, linked to events such as ENSO (El Nino-Southern Oscillation), the Arctic Oscillation/North Atlantic Oscillation;

• other effects of internal forcing factors, such as quasi-random events like volcanic eruptions, or external factors such as changes in solar irradiance or cosmic radiation on the system whose effects on climate remain a matter of debate.

Up until now, however, these different issues and processes have received some attention in the scientifi c community, but

in a rather “offl ine” mode (see fi gure below, which shows the possible changes in runoff in the Rhone River in Switzerland, based on the aggregate, but computed separately, effects of changes in precipitation, snow and ice, and hydropower reservoir management). What is proposed here is to explore these processes in an integrated manner rather than as independently occurring elements of the system, at widely varying time and space scales. It is this holistic approach to non-linearity and feedbacks in the climate system that would enable the University of Geneva’s Physics section to play a leading role.These issues warrant considerable attention because the proximity in time of possible bifurcation points is not known with any degree of confi dence today, and yet the passage through a bifurcation could result in numerous impacts and possible irreversibility of the system. Extreme events (heat waves, heavy precipitation, hurricanes and windstorms, for example), which are the most costly elements of climate in human and economic

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2 The scientific ambitions

A 3D view of the Lorenz attractor of climate, illustrating the inherent chaotic nature of the system as it changes from one state to another. (Credit: UNIGE, C. Berthod)


39

terms, are tenuously linked to a number of interacting processes within the Earth’s system; if the system enters into a more volatile or chaotic mode, then the frequency and intensity of extremes could be well beyond that which current climate models suggest may occur by the end of this century.Such research requires access to very high-performance computational resources that for years have been undergoing continuous development and upgrading. Simulation-based research fosters knowledge creation, enabling researchers to close the gaps in the understanding of fundamental physical mechanisms and improve the predictive capability of models. New computer architectures that enable innovation are entering the research world; indeed, these computers should help drive the development of a new generation of climate models, superseding current modeling techniques that represent iterative improvements to techniques developed half a century ago. These models will implement both coupling between non-linear processes and their advanced statistical description. The combination of state-of-the-art models and very high performance computing will enable the testing of ways to limit the most negative impacts of a changing climate, particularly if the system crosses as yet unknown bifurcation points, and to assess the infl uence on climate of national and international policies in the fi elds of energy, transportation, urbanization and natural resources, such as agriculture, water, forests and soils.The Department of Mathematics of the University of Geneva has a long tradition in the numerical solution of differential equations. Several of the best numerical integrators for ordinary differential equations have been developed here and are now used worldwide. More recently, the numerical analysis group has also developed substantial expertise in the adaptive numerical solution of partial differential equations. These techniques have, for example, been used successfully for the simulation of extreme events on parallel computers, such as the 2004 tsunami in the Indian Ocean. Techniques for the coupling of highly sophisticated partial differential models, like for example in the coupling of the ocean and the atmosphere, are a further area of expertise.

These advanced mathematical methods are well suited to the atmospheric-climatic system and appear to be a particularly promising approach to extreme events and bifurcations.A further spin-off from this detailed focus on non-linear climate dynamics will involve the application of models dedicated to Earth-system research to other atmospheres. The ultimate goal is to simulate climatic conditions that could exist on a limited number of extrasolar planets, or exoplanets, in order to assess whether a number of environmental prerequisites exist in the form of heat, water, carbon and oxygen that could be adequate for some form of life to exist on these planets. This opens up an entirely new range of opportunities for climate research at the University of Geneva – in close collaboration with the Geneva Observatory (Theme 1), discoverer of the fi rst exoplanets – and to new and unique domains in teaching and training.


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2. Ultrafastlasersforclimateresearchandatmosphericsounding

As mentioned above, initial and boundary conditions are critical to climate modeling. Lasers have long been used to observe the atmosphere, offering unique three-dimensional remote mapping features. Researchers from the University of Geneva, together with the European consortium called Teramobile (www.teramobile.org), have further enriched the information yield of laser remote sensing by using laser-induced plasma filaments. Filamentation results from a dynamic balance between Kerr self-focusing and defocusing by the self-generated plasma. They consist in self-stabilized structures of some 100 μm in diameter and up to several hundreds of meters in length. Their high local intensity (typically 5 . 1013 W/cm2) induces ionization (typically 1016 cm-3) as well as strong self-phase modulation, leading to the emission of a broadband white light supercontinuum from 230 nm to 4,5 μm. A significant amount of this coherent white light is emitted backward, which has opened new perspectives for atmospheric remote sensing techniques such as Lidar (light detection and ranging). The supercontinuum is then used as a white light laser source, and its backward emission is detected as a function of the light pulse flight time (and thus as a function of distance, like a radar). This provides unique access to a full three-dimensional analysis of multiple pollutants and trace gases in the atmosphere simultaneously. The Geneva group (Wolf) also demonstrated for the first time the remote detection and identification of bioaerosols in air using ultrafast multi-photon spectroscopy. The use of coherent control strategies shows that fluorescence from bacteria can be distinguished from other non-biological aerosols, such as traffic-related particles. Aerosols are known to represent the largest uncertainty in radiative forcing models, both through direct (absorption, albedo) and indirect (cloud condensation nuclei) effects. A key objective for the next decade will be the quantitative concentration measurement and identification of aerosols, and in particular of bioaerosols. The importance of bioaerosols was

recently evidenced (Jaenicke, R., 2005: Science) as amounting to as much as 25% of the total content of particles in the atmosphere.

Control of atmospheric processes and geo-engineering

Teramobile’s most spectacular finding is that laser filaments can not only characterize the atmosphere, but can also modulate fundamental atmospheric processes. If proven successful, these technologies will provide new possibilities for geoengineering, and, ultimately, significant beneficial effects in both human and economic terms.

This is, in particular, the case of extreme quasi-random events like lightning strikes. A technique to trigger lightning using rocket-pulled wires was developed in the 1970s. However, the number of rockets available during a thunderstorm is limited by the launch pad, which can host 5 to 10 rockets in typical facilities and cannot be refilled before the end of the thunderstorm. Furthermore, the success rate depends strongly on the instant when the rocket is launched. A continuously operating technique to trigger lightning would therefore be highly desirable.

Physicists at the University Geneva and the Teramobile team first demonstrated the capability of filaments to trigger megavolt-class electric discharges. By connecting two electrodes that were several meters apart, the laser filaments reduced the breakdown voltage by 30% and allowed discharges in conditions where they would not occur without the laser. Furthermore, these triggered discharges are guided along the laser filaments rather than following the erratic path typical of a classical electric discharge.

Transposition of the process to real scale thunderstorms is a challenging task, but promising results were already obtained during a field campaign where intra-cloud discharges within thunderclouds were clearly triggered by the Teramobile laser. However, no lightning strikes were guided down to the Earth.

Further developments towards lightning control by lasers include the use of higher laser power and the use of pulse sequences that optimize plasma generation. This technique will not only allow the triggering of lightning on demand for fundamental studies,


41

Free (left, A) and laser guided (right, B) high-voltage discharges. The high-voltage electrode (spherical, on the left) represents the cloud, while the plane electrode (right) is grounded. (Credit: UNIGE, J.-P. Wolf)

but it may also allow for the protection of critical facilities such as airports or power plants against direct strikes and indirect effects, i.e., electromagnetic perturbations induced by the transient current of some 100,000 amperes. An even more critical issue for humankind is precipitation control. Considerable efforts have been made with respect to water condensation and rain control in the USA and China, though with conventional techniques that are neither effi cient nor environmentally friendly (rocket seeding with silver iodide particles). The University of Geneva recently opened new perspectives in this respect by producing water vapor condensation in the atmosphere with laser induced plasma fi laments. The results, published in Nature Photonics in 2010, attracted tremendous attention, both from the scientifi c community and from the media.A particularly impressive observation is that laser fi lament induced condensation occurs even at low relative humidity (70%), where natural condensation would never occur. The underlying mechanisms involve complex non-linear photochemistry as well as ion-mediated nucleation of condensation nuclei. Further experimental and theoretical investigations will be performed in

order to optimize the process and evaluate the possible scaling up to macroscopic effects (cloud formation modifying albedo, rain modulation, etc.). These studies will have some further added-value through tighter links with the international CLOUD experiment at CERN, which aims to understand cloud formation in the presence of high-energy particles in a unique cloud chamber.In order to assess when and how to best use the laser fi lament technology to potentially modulate the severity of strong convection (including possible extreme downpours, hail and lightning strikes), it is necessary to undertake both theoretical and observational studies of these events. In particular, it is of interest to determine for various parts of the world where privileged zones for intense convection occur, what the favored triggering mechanisms are, and how the micro-scale (i.e., cloud microphysics) and larger scales (i.e., entire clouds or cloud fi elds, and their dynamic characteristics, including low-level convergence, lateral and fi nal entrainment/detrainment, and local thermal stability) interact. Much work on deep convection has been done for decades on both the micro- and macro-scales, but attempts to investigate both scales simultaneously have happened only rarely.

A B


42Cloud of water droplets (illuminated by a green laser) produced by laser filaments in air. (Credit: UNIGE, J.-P. Wolf)


43

While the theoretical ground work and the in situ observations enabling case study zones to be established will provide guidance for the laser experiments, the results of the laser-based studies will in turn help improve theoretical modeling of the processes involved. There is thus a clear incentive to establish the present joint approach – atmospheric physics and laser experiments – that will mutually feed each other and thus greatly refi ne the understanding of the processes involved.Improved atmospheric and cloud models could then be applied to provide some measure of advanced warning of imminent extreme weather – beyond simple “real-time” analyses – thereby enabling the weather-modulating laser system to be positioned in time to test the system under real conditions and assess its potential for reducing the severity of extreme weather. If the experiments are shown to be successful, a future step could involve the estimation of conditions under which these extreme convective systems may evolve in a changing climate, both spatially and also in intensity and frequency. In terms of current and future discussions on adaptation strategies with respect to the impacts of climatic change, such knowledge would be of use in establishing a network of weather-modulating lasers aimed at alleviating the severity of the impacts.

4. Conclusion

The University of Geneva has the unique opportunity to bring together the capacities and experience to develop the integrated approaches described above, combining atmospheric modeling, multi-parameter remote sensing, and weather engineering. Such a combined approach could renew the paradigm of both the understanding of climate change and the way to address it to minimize its consequences on the Earth.


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1. Beniston, M., 1997: From Turbulence to Climate. Springer Publishers, Heidelberg/Berlin/New York, 328.

2. Beniston, M., 2010 : “Impacts of climatic change on water and associated economic activities in the Swiss Alps”, Journal of Hydrology, doi:10.1016/j.jhydrol.2010.06.046.

3. Beniston, M., D. B. Stephenson, O. B. Christensen, C. A. T. Ferro, C. Frei, S. Goyette, K. Halsnaes, T. Holt, K. Jylhä, B. Koffi, J. Palutikoff, R. Schöll, T. Semmler, and K. Woth, 2007: “Future extreme events in European climate; an exploration of Regional Climate Model projections”, Climatic Change 81, 71.

4 . Beniston, M., 2007: “Entering into the ‘greenhouse century’: recent record temperatures in Switzerland are comparable to the upper temperature quantiles in a greenhouse climate”, Geophysical Research Letters 34, L16710.

5. Courvoisier, F., V. Boutou, H. Rabitz, J.-P. Wolf, 2006: “Discriminating Bacteria from other Atmospheric Particles using Femtosecond Molecular Dynamics”, Journal of Photochemistry and Photobiology A 180, 300.

6. Kasparian, J, M. Rodriguez, G. Méjean, J. Yu, E. Salmon, H. Wille, R. Bourayou, S. Frey, Y.B. Andre, A. Mysyrowicz, R. Sauerbrey, J.P. Wolf, L. Woeste, 2003: “White Light Filaments for Atmospheric Analysis”, Science 301, 61.

7. Kasparian, J., R. Ackermann, Y.B. Andre, B. Prade, G. Mechain, G. Méjean, P. Rohwetter, E. Salmon, V. Schlie, J. Yu, A. Mysyrowicz, R. Sauerbrey, L. Wöste, J.P. Wolf, 2008: “Electric Events Synchronized with Laser Filaments in Thunderstorms”, Optics Express 16, 5757.

8. Rial, J., R.A. Pielke, M. Beniston, M. Claussen, J. Canadell, P. Cox, H. Held, N. de Noblet-Ducoulet, R. Prinn, J. Reynolds, and J.D. Salas, 2004: “Non-linearities, feedbacks and critical thresholds in the Earth’s climate system”, Climatic Change 65, 11.

9. Rohwetter, P., J. Kasparian, K. Stelmaszczyk, S. Henin, N. Lascoux, W. M. Nakaema, Y. Petit, M. Queißer, R. Salamé, E. Salmon, Z. Hao, L. Wöste, J.-P. Wolf, 2010: “Laser-induced Water Condensation in Air”, Nature Photonics 4, 451.

10. Roth, M., L. Guyon, J. Roslund, V. Boutou, F. Courvoisier, J.P. Wolf, H. Rabitz, 2009: “Quantum Control of Tightly Competitive Product Channels”, Physical Review Letters 102, 253001.



46

Light and matter are the basic ingredients of our daily world. The precise understanding and detailed control of both entities have developed over many decades worldwide, with remarkable contributions from the University of Geneva. Signifi cant breakthroughs have been made owing to the emergence of novel experimental capabilities to control light at the level of a single photon, to synthesize artifi cial materials with single-atom precision, and to manipulate electrons and atoms one by one. Such an unprecedented level of control has had a tremendous impact on our abilities to design systems and synthesize materials with properties engineered at will, one of the great contemporary challenges for physicists. The single photon provides novel avenues to exploit the quantum nature of light in advanced applications of entanglement and exploration of fundamental quantum mechanics. Ultimately an incredibly fertile arena for novel scientifi c challenges and discoveries is opened where experimentation and theory closely interact.

New classes of materials continually energize research, with sudden and often unanticipated surges of worldwide activity every few years over the past decades. Recent examples include high-temperature superconductivity, carbon nanotubes, graphene, multiferroics, topological insulators and many more. Likewise, the control of photons has made tremendous progress, with the demonstration of long distance entanglement, teleportation and, most recently, photon-matter entanglement. Artifi cial systems where “cold” atoms are maintained in custom designed lattice confi gurations by means of laser arrays open further fascinating possibilities to simulate fundamental aspects of materials and theoretical solid state physics. Members of the Physics section of the University of Geneva have made a range of key contributions to a number of the topics mentioned above over the past 20 years. The new Center is to thrive on this vast expertise with the aim of fostering synergies stimulating original ideas and supporting ambitious projects in these fast moving areas. The close collaboration between experimentation and theory is a very important asset in this fascinating endeavor.

ThEmE 3.Quantum photonics and nanostructured devices for electronicsParticipants in this theme (status 2011): Markus Büttiker, Antoine Georges, Thierry Giamarchi, Nicolas Gisin, Corinna Kollath, Alberto Morpurgo, Patrycja Paruch, Christoph Renner, Jean-Marc Triscone, Dirk van der Marel, Jean-Pierre Wolf


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1. Artificialmultilayerandinterfaceengineering

Electronics plays an increasingly important role in our everyday lives. It affects the way we work, the way we communicate and even the way we entertain. Electronics is at the core of the transition of the XIXth century industrial society to the XXst century information-based one. The sustained progress in conventional electronics supporting the very successful information technology we live with and benefi t from is inescapably reaching an end, as many key parameters following Moore’s law are nearing impassable barriers. Exciting new possibilities beyond standard electronics are provided by novel oxide materials where electronic correlations allow collective phenomena like magnetism, superconductivity, ferroelectricity and multiferroism. Interfaces and domain walls in such materials are of particular interest. These intrinsically nanoscale structures can exhibit promising new properties, sometimes radically different from their already multifunctional parent materials. Continued developments in complex oxide synthesis have brought the fi eld to an unprecedented level, allowing for the realization of atomically precise artifi cial oxide nanostructures. Geneva is among the pioneers in controlling the artifi cial multilayer synthesis of complex oxides (Fischer, Triscone). Various functional oxides such as ferroelectrics, high-temperature superconductors, colossal magnetoresistive alloys and magnets can be combined at the nanoscale, offering tremendous possibilities for creating artifi cial multifunctional materials and devices (Triscone). In addition, high-quality ultrathin oxide fi lms can now be grown directly on silicon, offering great potential for innovative applications (Triscone).Research on oxide heterostructures has been internationally recognized to be at an incipient stage, comparable to that of semiconductors sixty years ago, with potentially an even greater future impact. A recent report by the United States Department of Energy states that “Given the richness of collective phenomena in correlated materials, the spectrum of science to be explored in

Schematics of the broad range of properties available in oxide materials that can be combined with atomic scale precision (top). Nanostructure realized at the interface between two oxide materials (bottom). (Credit: UNIGE, J.-M. Triscone)

500nm


49

ThEmE 3.Quantum photonics and nanostructured devices for electronics

such layered structures is almost limitless.” Exciting perspectives in this fi eld include reports on such unusual phenomena as the appearance of a two-dimensional electron gas (2-DEG) between insulating oxides, the emergence of improper ferroelectricity due to the coupling of competing instabilities and breaking of symmetry at the interface, and even the emergence of superconductivity between non-superconducting materials (Triscone). Engineering domain walls within or between these oxide materials is a promising pathway to new functionalities, including metallic, photovoltaic, ferromagnetic, ferroelectric and ferroelastic responses (Triscone, Paruch). The sheer extent of possible combinations is overwhelming, and highlights the crucial role of close collaboration between theoretical modeling and experimental investigation to identify the most promising candidates.

Artifi cial interfacial structures are not only highly interesting from the point of view of fundamental physics, they can also be used as nanoscale device components in miniaturized transistors and other memory elements, junctions and sensors, to name only a few. The vision underlying such research is to develop interfacial systems whose electronic properties can be designed by exploiting electron interaction processes and other microscopic degrees of freedom (electron spin, electronic orbital states, phonons, etc.). The core objective is the investigation of electronic properties and the control of electronic correlations and quantum ground states. The experimental approach is inspired by mesoscopic physics: interfaces will be engineered to control the microscopic processes of interest. The strategy to control the electronic properties of interfaces and grain boundaries will rely on a number of physical concepts and on different classes of materials enabling their implementation (Giamarchi, Paruch, Triscone).

Many complex materials with extraordinary properties whose performance is dominated by quantum correlations and strong interactions have been developed, and applications exploiting highly non-trivial phenomena already exist. However, many of the underlying principles of these complex quantum systems, and in particular their dynamic manipulation, are far from being

understood. The dynamic control of quantum correlations and strong interactions will be a necessary prerequisite for future devices exploiting, for example, transport at nanoscale (Büttiker) or quantum computing. Close collaboration with theory to understand the fundamental principles (Büttiker, Georges, Giamarchi, Kollath) will be paramount to the targeted search and tailored engineering of more advanced materials and devices.

2. Quantumopticsandnanophotonics

To understand and ultimately control the quantum nature of photons and atoms, physicists will have to master complex quantum systems, like multi-photon states, ensembles of atoms and the interaction between them. The core focus is to explore the quantum nature of photons and atoms. This covers aspects of applied physics, like quantum cryptography and teleportation, and more fundamental aspects, like Bell’s inequalities and nonlocality. Applications of these remarkable quantum physics properties require the development of meso- and macroscopic systems with specifi c properties, for example long coherence times. Mastering these technologies will enable, among other applications, simulations of complex quantum materials and systems. It will also bring us a step closer to a quantum computer. From a more fundamental perspective, these technologies and conceptual breakthroughs will underline the role of Bell inequalities as the signature of quantumness and the role of nonlocal correlations as an entirely new kind of resource for information processing without any equivalence in any other fi eld of science. The ultimate goal is a better understanding of the origin of nonlocal correlations that seem to emerge, somehow, from outside space-time.Progress in quantum science and technology is fast, with a number of rapidly evolving challenges. The main limitation to today’s quantum communication is the distance, limited to a few tens of kilometers of telecom optical fi ber. Hence, one grand challenge is the realization of quantum repeaters (Gisin). These require the

50

2 The scientific ambitionsII The scientific ambitions

Interference pattern among the nonlinear emissions of two neighboring nanoparticles excited by an evanescent wave at the second harmonic. (Credit: UNIGE, J.-P. Wolf)

51

distribution of high-quality photonic entanglement over large distances, and high-fi delity teleportation and of multi-mode quantum memories with memory times approaching 1 second and more than 90% effi ciency. This quest will keep the science community busy for at least the next decade. It involves not only photonics, but also atomic ensembles (the most promising technology for quantum memories) and, most likely, solid-state matrices to host these atomic ensembles. Hence, this goes also into the direction of mesoscopic quantum systems and will greatly benefi t from collaborations with solid state physicists. In all cases, the applications reach well beyond quantum communication and further progress towards quantum simulations and computation.A better understanding of nonlocal quantum correlations will come through playing with such correlations and from dismantling them into more elementary correlations, like children dismantle their toys to get familiar with their structure. Progress will also come from abstract studies on the power of such nonlocal correlations as a resource for information processing, for example guaranteed private randomness. Along these lines, the multipartite cases, almost a no-man’s-land in terms of current understanding, are fascinating. Finally, the conceptual tension between quantum nonlocality and relativity should be investigated. Interestingly, this very fundamental research has been shown to easily cross-fertilize with experimental physics.Quantum bits, the so-called qubits, are central to all quantum information processing. Qubits are routinely realized with photons and ions. A grand challenge is to develop macroscopic qubits, that is, to bring the quantum world up to human scale. One possibility in that direction consists of amplifying one photon, e.g., a photon entangled with another photon. If the amplifi cation is realized by a “phase-covariant cloner”, as is the case with parametric amplifi cation, the amplifi cation process is unitary and thus, if the losses are minimal, the microscopic qubit structure should be amplifi ed to the macroscopic, many photon amplifi ed quantum state of light. More generally, bringing the quantum world closer to us implies larger objects, many subsystems and large distances, which are all fascinating challenges.

Finally, a general theme will be light-matter interaction. In addition to being the hobby-horse of many physicists in the community, this is the enabling technology that will allow the achievement of most – if not all – of the grand challenges in quantum technologies. Indeed, atoms enjoy the longest coherence times, while photons are central to quantum communication thanks to their intrinsic property as fl ying qubits. Laser pulses are by far the best tool for driving atoms from one quantum state to another. Accordingly, the reversible mapping of a quantum state from one species, e.g., photons, to another, e.g., atoms, enables one to take advantage of the best of each species. First successes in these directions have recently been obtained in Geneva (Gisin). Nanocrystals with magnetic or non-linear optical properties are currently revolutionizing the fi elds of bioimaging and nanomedicine (Wolf). In particular, second harmonic radiation imaging probes (SHRIMPs) based on inorganic nanocrystals are very attractive, being nontoxic, bright, stable against long-term excitation and able to generate a sharp contrast against background signals. The non-resonant nature of the second harmonic process by sub-wavelength structures provides extreme fl exibility towards the excitation wavelength, from ultraviolet to infrared. While infrared can be used for deep imaging in tissues, shorter wavelengths can serve as nanotherapeutics. Future research is dedicated to multimodal probes (magnetic and optical) that can bind to cellular targets for selective detection and therapy of cancer cells (Wolf, in collaboration with the Faculty of Medicine).


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3. Nanoscaledevicesandatomic-scalestructuring

The use of nano- and atomic-scale structured devices for the investigation of the electronic properties of novel materials is a virtually unexplored area of research with great potential for the coming decades. The conventional approach to the study of electronic properties of new materials focuses on the investigation of their bulk properties. The strategy based on nanostructured devices is different. It aims at designing specifi c structures to target, and ideally control, individual microscopic electronic processes of interest. Nanofabricated devices can be used to tune the density of charge carriers by means of electrostatic gating and allow the creation of non-equilibrium electronic distributions. Controlled deposition of single atom scattering centers on conducting surfaces can be used to reveal correlated electron distributions in momentum space by means of scanning probes. Both approaches enable an exquisite energy resolution by means of low-temperature transport measurements and provide considerable fl exibility through the design of the device confi guration. These possibilities open unique opportunities not accessible to experiments probing the bulk of the materials (Büttiker, Morpurgo, Renner). During the past few decades, nanostructured devices have been realized on materials that are by now considered conventional. These are common semiconductors (such as silicon, III-V compounds, and their hetero-structures), metals (copper, gold, etc.), and superconductors (aluminum, niobium, etc.) in which interactions are usually weak. Their investigation using nano-electronic devices has led to the fi eld of mesoscopic physics. The level of understanding and control of electronic properties that has resulted from research in this fi eld have by far exceeded all initial expectations. Impressive discoveries have been made (e.g., the observation of integer and fractional quantum Hall effects) and new applications have emerged, ubiquitously present in appliances used in everyday life (e.g., lasers based on semiconductor heterostructures). Over the last few years, many

elements have come into place that permit the generation, manipulation and detection of a few electron quantum states, the observation of macroscopic quantum phenomena, and the preparation and detection of quantum states in solid-state devices. In parallel, there has been great progress in the theoretical description of mesoscopic electronic systems (Büttiker).There is huge potential in applying the same mesoscopic physics strategy to novel materials in which different types of interactions play a dominant role and cause the emergence of strong correlations. Phenomena involving strongly interacting electrons include high-temperature superconductivity, different types of magnetism, Mott-Hubbard insulating states, and many more. Reaching a full understanding of these phenomena is one of the outstanding problems in condensed matter physics. Examples are already known of breakthrough experiments performed with devices based on complex materials, e.g., nanostructured superconducting quantum interference devices (SQUIDs) that were fi rst used to prove the d-wave nature of copper oxide

Prediction of the signature of an entangled two-electron state in the quantum shot noise P (vertical axis) of a submicron electrical conductor: the state is created by two single electron sources with a phase difference of φ and can be tuned by the phases of two distant interferometers φL and φR (horizontal axes). (Credit: UNIGE, M. Büttiker)


53

superconductors. These examples demonstrate the potential of a mesoscopic physics approach. So far, however, they represent more the exception than the rule and the goal of the Center is to extend a device-oriented approach systematically to address a much broader class of materials and phenomena (Büttiker, Georges, Giamarchi, Kollath, Morpurgo, Paruch, Renner, Triscone). Separately addressing the different microscopic processes responsible for a same physical phenomenon of interest should be possible by exploiting the fl exibility offered by artifi cially designed device structures. The idea is to split a complex problem into a number of simpler ones that can be addressed individually using suitably designed nanodevices. Ideally, the artifi cial structures that will be created should allow the probing, and possibly engineering, of interactions of electrons with other degrees of freedom (e.g., lattice vibration, orbital excitations, spins and pseudo-spins), and among themselves. The development of new, “unconventional” experimental techniques for the fabrication of devices giving control over material properties is—and will remain—a crucial integral part of materials research. Microscopic electronic processes can be probed through focused quantum transport experiments in nanostructures and devices. A nanoelectronics approach provides a range of unexplored electronic systems in which new phenomena are expected to occur. Their study will deepen our basic understanding of complex electronic processes in solids, and is likely to lead to unexpected discoveries. An example is provided by the use of ionic liquids for electrostatic gating (Morpurgo, Triscone). Such a technique enables the accumulation of surface charge densities in excess of 1015 carriers/cm2. This value corresponds to approximately one additional electron per each atom present at the material surface, and to an increase of two orders of magnitude as compared to what was possible until very recently. The discovery of graphene, made through the study of transport in nanodevices and awarded with the 2010 Nobel Prize in physics, provides another example. It shows that vast unexplored research areas can become accessible through simple and original approaches. It also illustrates that unexpected discoveries of new materials and physical phenomena are made

Atomic scale scanning tunneling microscopy (STM) micrographs of self assem-bled model systems on Si(001) that will enable the experimental exploration of the quantum phenomena emerging in one dimensional electronic systems.(Credit: UNIGE, C. Renner.)


54

regularly, which are of great fundamental interest and have the potential for a long-lasting technological impact. Another promising line of research is in quantum coherent electronics that can eventually replace classical dissipative information processing. Coherent electron transport in sub-micron sized samples has been of interest since the early eighties. Initial predictions of persistent currents in purely normal structures and Aharonov-Bohm effects in loops connected to metallic contacts have been confirmed in many experiments. Ring structures test (essentially) single particle interference. The modern task is to achieve multiparticle interference effects that are a signature of entanglement and can be used to harness the full potential of quantum mechanics. Over the last few years many elements have come into place that allow the generation, manipulation and detection of few electron quantum states. A novel type of Aharonov-Bohm effect that uses two electrons to encircle a flux has been proposed (Büttiker) and novel electron sources that can inject electrons one at a time into an electrical conductor have been developed.Scanning local probes has given the scientific community an unprecedented grip on materials at the single atom level in real space. The great majority of studies using such probes has been performed on single crystals and thin films. Only a limited number of experiments, mostly atomic force microscopy (AFM) based, are performed on devices. Exploiting atomic scale engineered structures on devices and materials in various forms offers a number of exciting prospects. Of particular interest is the possibility to drive and reveal novel electronic and magnetic properties. Recent implementations of combined scanning tunneling microscopy (STM) and AFM offer enhanced experimental capabilities with a significant impact on fundamental materials and device physics. It will, for example, allow the addressing of numerous open questions in systems that are in close proximity to insulating phases, both in real space and in phase space. This association will also open experimental ways to tackle fundamental questions of low-dimensional physics, a very modern and active field of research, by exploring self-assembled atomic scale model systems (Büttiker, Georges, Giamarchi, Kollath, Renner).

Time-evolution of the spectra of strongly driven complex quantum states. (Credit: UNIGE, C. Kollath.)

One of the spectacular developments in STM-based tunneling spectroscopy is the possibility to achieve momentum resolution exploiting naturally occurring and artificially engineered quasiparticle interference. The idea is to image the interference patterns generated by incoming and scattered electronic waves in the vicinity of structural and electronic defects and impurities. Step edges and bulk impurity atoms are generally used to generate quasiparticle interference patterns (QPI). But one can also engineer these patterns by, for example, controlled deposition of single atom impurities on the surface by means of an STM or AFM. Most recently, vortices have been used to trigger QPI on superconductors, a very interesting extension of Fourier Transform (FT) STM, because vortices not only scatter quasiparticle states, they also induce a time reversal symmetry breaking component providing additional information on the scattered electronic states. The Center anticipates novel insight into the electronic structure, including the Fermi surface topology, of a range of materials and nano-devices using STM/AFM based QPI. This technique provides information normally obtained

Time

Driv

ing

freq

uenc

y


55

with low-energy electron diffraction (LEED) and angle-resolved photoemission spectroscopy (ARPES), but with signifi cantly better spatial resolution and on much smaller specimen (Renner). Progress in sub-wavelength optical spectroscopy on the nanometer scale using near-fi eld optical probes provides a versatile way to excite, read and map quantum states in buried layers, single atomic layers, nanometer size devices and combinations thereof. Spin- and orbital polarization can be probed and manipulated through the intrinsic spin carried by the photons (van der Marel). A major challenge to theory in the above context is disorder. Although it can be considered as a nuisance, it is ubiquitous in condensed matter and understanding its effects is crucial. Most of the time, disorder leads to small modifi cations compared to the pure case, but it can also lead to qualitatively new phenomena or even useful effects. In many systems, disorder can lead to the physics of glasses, which we barely understand. How to tame and describe such materials is an issue for which we do not yet have good theoretical concepts. Most of the scientifi c community’s understanding of many particle systems assumes that they are in thermodynamic equilibrium. However, dynamics and non-equilibrium phenomena have reached growing importance in condensed matter physics, quantum information processing and ultra-cold quantum gases over the last decade. This can be the transport through ever smaller nanostructures (Büttiker) and even single molecules, the transient effect in photovoltaic systems, quantum operations or the motion of a domain wall in magnetic storage situations (Giamarchi). The understanding of quantum dynamics, in particular the infl uence of dissipation and decoherence in many body systems, is still at an early stage. Both the description of these situations in classical and in quantum systems require new tools that scientists are only starting to develop (Büttiker, Giamarchi, Kollath).

4. Conclusion

Theory of condensed matter is there to explain and predict the phenomena that are occurring in the realm of materials. Although theories are primarily concerned with fundamental physics, it is clear that they have opened the way to a world of applications. Numerical techniques and a strong and constant coupling with experimentalists are very important in condensed matter theory. Theory is in constant evolution given the progress and richness of the experimental side of condensed matter physics and the constant fl ux of new materials and challenges. Likewise, experimentalists are continuously challenged by the fast-moving condensed matter theory. A wealth of ideas emerging on the smallest length scales also drives a constant need for ever more sophisticated equipment and experiments. The new Center will offer the best possible interdisciplinary environment to match all these boundary conditions, from world class theory to state-of-the-art commercial and in-house developed instrumentation and experiments. Working towards the above-mentioned goals requires a multi-faceted approach relying on close collaboration between different experimental groups and between theoretical and experimental approaches. New collaborations between quantum optics and materials science are particularly promising for both fi elds. All of the above will benefi t from being immersed into a larger group with extensive and diverse expertise. The new Center will foster collaboration and get scientists of very different backgrounds to talk to each other so that any progress in any subfi eld can quickly fertilize the others.


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1. Bäumner, R., L. Bonacina, J. Enderlein, J. Extermann, T. Fricke-Begemann, G. Marowsky and J.-P. Wolf, 2010: “Evanescent-field-induced second harmonic generation by noncentrosymmetric nanoparticles”, Optics Express 18, 23218.

2. Bousquet, E., M. Dawber, N. Stucki, C. Lichtensteiger, P. Hermet, S. Gariglio, J.-M. Triscone and P. Ghosez, 2008: “Improper ferroelectricity in perovskite oxide artificial superlattices”, Nature 452, 732.

3. Clausen, C., I. Usmani, F. Bussières, N. Sangouard, M. Afzelius, H. de Riedmatten and N. Gisin, 2011: “Quantum storage of photonic entanglement in a crystal”, Nature, 469, 508.

4. Extermann, J., L. Bonacina, E. Cuña, C. Kasparian, Y. Mugnier, T. Feurer and J.-P. Wolf, 2009: “Nanodoublers as deep imaging markers for multi-photon microscopy”, Optics Express 17, 15342.

5. Giamarchi, T., 2004: “Quantum Physics in One dimension”, Oxford University Press.

6. Heersche, H.B., P. Jarillo-Herrero, J.B. Oostinga, et al. 2007: “Bipolar supercurrent in graphene”, Nature 446, 56.

7. Hulea, I.N., S. Fratini, H. Xie et al. 2006: “Tunable Frohlich polarons in organic single-crystal transistors”, Nature Materials 5, 982.

8. Kollath, C., A. Laeuchli, E. Altman, 2007: “Quench dynamics and non equilibrium phase diagram of the Bose-Hubbard model”, Physical Review Letters 98, 180601.

9. Kuzmenko, B., E. van Heumen, F. Carbone, and D. van der Marel, 2008: “Universal Optical Conductance of Graphite”, Physical Review Letters 100, 117401.


10. Reyren, N., Thiel, S., Caviglia, A.D., Fitting Kourkoutis, L., Hammerl, G., Richter, C., Schneider, C. W., Kopp, T., Ruetschi, A.-S., Jaccard, D., Gabay, M., Muller, D. A., Triscone, J.-M. and Mannhart, J., 2007: “Superconducting Interfaces between Insulating Oxides”, Science, 317, 1196.

11. Renner, Ch. and Ø. Fischer, 1995: “Vacuum tuneling spectroscopy and asymmetric density-of-states of Bi2Sr2CaCu2O8+d”, Physics Review B 51, 9208.

12. Renner, Ch., G. Aeppli, B.G. Kim et al., 2002: “Atomic-scale images of charge ordering in a mixed-valence manganite”, Nature 416, 518.

13. Roux, G., T. Barthel, I. P. McCulloch, C. Kollath, U. Schollwoeck, T. Giamarchi, 2008: “The quasi-periodic Bose-Hubbard model and localization in one-dimensional cold atomic gases”, Physical Review A 78, 023628.

14. Salart Subils, D., A. Baas, C. Branciard, N. Gisin and H. Zbinden, 2008: “Testing the speed of ‘spooky action at a distance’”, Nature, 454, 861.

15. Splettstoesser, J., Moskalets, Büttiker, M., 2009: “Two-Particle Nonlocal Aharonov-Bohm Effect from Two Single-Particle Emitters”, Physical Review Letters 103, 076804.

16. van Wees, B.J., H. van Houten, C.W.J. Beenakker, J.G. Williamson, L.P. Kouwenhoven, D. van der Marel, C.T. Foxon, 1988: Physical Review Letters 60, 848.


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Possibilities beyond our wildest dreams lurk in the treasure trove of quantum materials. Thanks to continued worldwide efforts in materials engineering, novel phases of matter are discovered at regular intervals, including different forms of magnetism used in electro motion and magnetic storage devices, superconductivity used for magnet design and lossless power transmission.

Since many of these functionalities exploit forms of collective behavior resulting from the correlated motion of electrons and atomic vibrations in a solid, innovative XXIst century applications rely on a profound knowledge of the physical properties of quantum materials. The correlated behavior of electrons, when combined with the laws of quantum mechanics, constitutes one of the biggest challenges known in theoretical physics. Yet novel numerical approaches, such as dynamical mean fi eld theory, have emerged in recent years, allowing for reliable predictions today and guiding experimental investigation through the immense universe of unexplored compounds that can in principle be formed by combining different elements of the periodic system.

Characterizing and understanding the next generation of electronic materials and devices requires increasingly sophisticated experimental techniques. These include advances in size reduction of scanning probe microscopes, novel optical techniques, and X-ray, neutron and photoelectron spectroscopy. These experimental techniques allow detailed mapping of the landscape of atoms, their charge and their spin, and unveil the properties and functionalities of novel perspective materials.

All these aspects form part of the research program in Geneva. The new Center will unite the experimental, theoretical and application-oriented teams presently scattered over several different locations.

ThEmE 4.Quantum materials

Participants in this theme (status 2011): Øystein Fischer, Antoine Georges, Thierry Giamarchi, Corinna Kollath, Dirk van der Marel, Alberto Morpurgo, Patrycja Paruch, Christoph Renner, Jean-Marc Triscone, Jean-Pierre Wolf


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Selection of superconducting materials sorted by their year of discovery and transition temperature. (Credit: UNIGE, C. Berthod)

1. Superconductivity

Year 2011 marks the 100th anniversary of the discovery of superconductivity. Discovered by the Dutch scientist Heike Kamerlingh-Onnes, superconductivity represents the amazing phenomenon of dissipationless fl ow of electric current. Due to the principles of quantum mechanics, the electrical current in a superconducting loop will fl ow forever. The quantum aspect of superconductivity is also responsible for a host of phenomena observed and applied in superconducting electronic circuits, ultrahigh precision magnetic sensors, radiofrequency fi lters and electronic resonators. After one century, this fi eld is still one of the most vital in condensed matter physics and continues to bring new surprises with major breakthroughs almost every three years. Most recently, the 2009 discovery of high-Tc superconductivity in a large group of Fe-based compounds has inspired researchers worldwide in their quest for novel superconducting materials.The most important contributions to this fi eld by members of the Center include:

- the discovery of a superconducting phase that is turned on by the application of a high magnetic fi eld (Fischer)

- the fi rst direct observation of the electronic vortex structure in high magnetic fi elds in high-Tc superconductors using scanning tunneling spectroscopy, which had been a longstanding challenge in the fi eld (Fischer, Renner)

- the discovery of a pseudo-gap above Tc in high-Tc superconductors using scanning tunneling spectroscopy (Fischer, Renner)

- The discovery of superconductivity at the interface between insulating SrTiO3 and LaAlO3 (Triscone)

- the fi rst artifi cially constructed insulator/cuprate superconductor superlattices (Triscone, Fischer)

- the discovery of superconductivity induced color change and high energy spectral weight transfer (van der Marel)

- the discovery of optical Leggett-excitons in the gap of a superconductor (van der Marel)

1900 1925 1950 1975 2000Year of discovery

-250

-200

-150

-100

Tran

sition

tem

pera

ture

(Cels

ius)

Liquid nitrogen

Concordia, Antarctica (-80°C)

Liquid He 0

50

100

150

200

Tran

sition

tem

pera

ture

(Kelv

in)

Hg Pb Nb NbNNbO Na

xWO

3

BaPb

1-xB

i xO3

LaBa

2Cu 3

O7

YBa2Cu3O7

Bi2Sr2Ca2Cu3O10

Tl2Ba2Ca2Cu3O10

HgBa2CaCu2O6

164 KHgBa2Ca2Cu3O8(30 GPa)

LaBa

2Cu 3

O7

(1GP

a)

Nb3Sn Nb3G

aNb

3Ge MgB2

K3C60LaFePO La

FeAs

O1-

xFx

SmFe

AsO

1-xF

x

RbCs

C 60Cs 3C 60

(1.4

GPa)

- the discovery of two energy scales and two distinct quasiparticle dynamics in the superconducting state of underdoped cuprates (Georges)

- the theoretical prediction of a moving glass state in vortex lattices (TGiamarchi)

- the invention of a cold high pressure densifi cation technique for strongly improved critical current and critical magnetic fi elds in MgB2 wires and tapes (Flükiger).

The development of superconducting materials that can be operated in ambient conditions (room temperature and one atmosphere pressure) will open the door to large-scale superconducting wire-grids. Other important developments for superconducting compounds, even when operating at low temperature, are to improve or make novel materials with high critical magnetic fi elds for use in superconducting magnets, and materials with good isotropic and high critical currents. In addition, a large interest for fundamental research is the development of superconductors with an unconventional (p-wave, d-wave) order


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parameter, and materials in which superconductivity occurs close to, or overlapping with, competing states of matter, such as (anti)-ferromagnetism (Morpurgo,1 Renner, van der Marel).Materials can be engineered where superconductivity co-exists with strong magnetic fi elds. The theoretical idea of the so-called exchange compensation effect in certain superconducting materials containing magnetic ions goes back to Vincent Jaccarino and Martin Peter (later rector of the University of Geneva), and was realized for the fi rst time by Øystein Fischer in the Chevrel-phase material EuxSn1 xMo6S8 ySey. Other substances with this interplay between magnetism and superconductivity are UGe2, and the high-Tc superconductor EuFe1.8Co0.2As2. The fi eld of superconductivity in magnetically polarized matter has strong potential for the discovery and application of novel emergent phenomena (Renner, van der Marel).In certain insulating materials a 2-dimensional superconducting state can be introduced by creating an interface between different insulating materials, or by applying a gate voltage across an insulating barrier, or through a combination of these two techniques. The introduction of ionic liquid gates that allow

Optical appearance of a thin Bi-2212 crystal. (Credit: UNIGE, A. Kuzmenko.)

charge accumulation in excess of 1015 carriers/cm2, corresponding to more than one electron/atom, enables the tuning of the properties of materials in unexplored regimes that have never been accessible in the past. These and other recent discoveries mark the start of a vast, unexplored research fi eld. The power of these techniques has been demonstrated recently, for instance, by gate-doping the surface of insulators into a superconducting state, and will be exploited over the next decade on a much broader class of materials ranging from unconventional superconductors to magnets and correlated electronic states (Morpurgo, Triscone).Superconductivity plays a key role in high fi eld magnets for medical applications, particle accelerators and thermonuclear reactors, while higher resolution magnetic resonance imaging furthers the development of improved high-Tc superconductor technology. Examples include:

• Plans to upgrade LHC – the Large Hadron Collider – in the short to medium term (2015-2020) with NbTi and Nb3Sn quadrupoles will require new radical approaches beyond existing NbTi and Nb3Sn technology.

• Superconducting cables based on Nb3Sn wires will be used to generate the high magnetic fi elds of up to 12 Tesla in ITER – the International Thermonuclear Experimental Reactor – needed to confi ne and shape the high-temperature plasma where nuclear fusion takes place.

Superconductivity also plays an important role in a variety of emerging and environmentally friendly applications in electric power infrastructure and transportation systems:

• Powerful new superconducting generators, wind turbines, cables, and fault current limiters will enhance the effi ciency and reliability of electricity generation, transport and distribution.

• The incorporation of superconductor technology into transportation system design (such as the recently accepted construction of the Chuo Shinkansen Maglev line between

1 - A young scientist, Carmine Senatore, has been selected to continue the research in applied superconductivity, which is formally in the group of Professor Morpurgo.

62

Tokyo and Osaka by Central Japan Railway, which is expected to start in April 2014) will improve the effi ciency and reduce the weight of propulsion systems (Morpurgo).

2. Novelperspectivematerials

In addition to superconductivity many other states of matter exist that are driven by the quantum character of matter and the collective behavior of elementary electrons and atoms. These include magnetism in 3D material, quantum magnetism in low-dimensions and frustrated lattices, charge and spin-fractionalization in high magnetic fi elds or reduced dimensions, to mention but a few. Theoretical ideas exist for several other states of matter with unexpected properties. These ideas spur the exploration of physical phenomena in novel perspective materials.

The most important contributions to this fi eld by members of the Center include:

- the invention of Dynamical Mean Field theory (Georges)

- the theoretical prediction of magnon condensation in magnetic materials (Giamarchi)

- the discovery of charged magnons (van der Marel)

- the discovery of a remarkable correlation between the Seebeck coeffi cient and the electronic specifi c heat in correlated electron systems (Jaccard)

- the discovery of domain wall creep in epitaxial ferroelectric PbZr0.2Ti0.8O3 (Paruch)

- the fi rst gate-induced insulating state in bilayer graphene devices (Morpurgo)

- the fi rst demonstration that trilayer graphene is a semimetal with gate-tunable band overlap (Morpurgo)

- the fi rst demonstration that the optical sheet conductance of graphite is 1/2 π e2/h (van der Marel).

Modern materials engineering allows for the composition of materials with complex stoichiometries in a very pure form, as single

crystals and/or thin fi lms. A very promising recent development combines aspects of two-dimensional physics, previously seen in thin fi lms, and interesting bulk properties known from crystals. This combination is present in a new class of bulk insulators with strong spin-orbit coupling, exhibiting topologically protected metallic surface states. This rapidly expanding class of materials includes HgTe quantum wells, Bi2Te3, half-Heusler compounds REPtSb (with RE=Rare Earth) and many other predicted systems. Theory is ahead of experimentation in this area, implying that a huge fi eld of materials research is now open in this direction. Many developments are probably still to come, especially since the contrast between different properties in the bulk (magnetic, superconducting, semiconducting) and topologically protected surface states offers many opportunities for the discovery of new physical phenomena: magnetic monopoles, Majorana fermions and axion physics (Morpurgo, Renner, van der Marel). Worldwide, a major effort concentrates on materials with coupling between magnetic polarization and electric fi eld, and/or vice versa. This effect is indicated as multiferroic behavior, a term introduced by Hans Schmid (University of Geneva) in 1994 (Schmid, H., 1994: Ferroelectrics 162, 317). This type of effect, which requires special

Fermi surfaces of BaVS3 calculated in the LDA—local density approximation—(top) and LDA+DMFT— local density approximation + dynamical mean-fi eld theory—(bottom) approximations. (Credit: UNIGE, A.Georges.)


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low-symmetry properties of the crystal structure, has been found in several materials; however, at room temperature the effect ceases to exist or becomes very weak. The great challenge is to make this type of coupling strong enough to be useful in devices at ambient conditions. Materials of current interest are BiFeO3 where ferroelectricity and antiferromagnetism exist, and the coexistence of paraelectricity and antiferromagnetism in LaFeO3. These are potential candidates for improper ferroelectricity, and electric-fi eld-controlled transitions between different states close in energy (Paruch).Crystal growth techniques often allow for the growing of materials with complex stoichiometries in a very pure form, usually much better than can be obtained from thin fi lms. Different compounds often have very similar lattice parameters and can be combined into high-quality, epitaxially grown interfaces. Its combination with suitably chosen thin fi lm material can provide access to novel states of matter at the interface. The combination of interesting substrate material crystal growth, including Mott-insulators and quantum magnets, and thin deposition has a high potential for the discovery of novel states of matter. Examples are the occurrence of metallic conduction – and even superconductivity – at the interface of two insulators, the control of microscopic interactions between electrons, the formation of ferromagnetic metals at the interfaces of two antiferromagnetic insulators, and anomalous critical behavior due to the coupling of order parameters. The choice of materials is dictated by the microscopic electronic processes to be controlled and by the quantum ground states aimed for. The Center will rely heavily on transition metal oxides that display an extraordinary variety of electronic properties: dielectrics, ferroelectrics, multiferroics, ferromagnets, metals and superconductors can all be found within the perovskite structure (van der Marel, Morpurgo, Triscone).The exquisite sensitivity of many novel electronic materials to external stimulae is promising for applications ranging from optical switches to chemical sensors. Recent examples include transition metal oxides and graphene. It is possible to design ways to tune and control the properties of correlated materials by applying external stimulae, or, vice versa, use the fact that changes

of material properties (charge density, magnetization, pressure) infl uence the optical appearance. Since photons carry internal angular momentum, the magnetic state of a material can be manipulated through interaction with light, a possibility that, with proper materials engineering, offers very interesting perspectives in science and technology, a potentially interesting fi eld that remains largely unexplored (van der Marel, Renner).

Many of the underlying principles of these complex quantum systems, and in particular their dynamic manipulation, are far from being understood. While the basic equations that describe the world of solids are very well known (namely the Schrödinger equation, or Dirac equation for relativistic electrons) the challenge posed by this fi eld comes from the complexity of a macroscopically large number of quantum particles interacting together. Recently a numerical method, the time-dependent density matrix renormalization group method, has been developed (Kollath) that allows for effi cient treatment of the dynamic of non-relativistic one-dimensional systems. This problem resists numerical and analytical attempts to crack it in higher dimensions.

Given that many of the remarkable recently discovered materials require such an understanding, there will be the need for many efforts in this direction in the future. Understanding such a problem should open the way to the design of new materials with undreamed of properties today. Fortunately, several special limiting cases (one dimensional and infi nite dimensional limits) can be solved. For realistic materials property modeling in two or three dimensions, numerical techniques play a central role. They complement analytical techniques and the combination of the two is an unbeatable tool. This is true for ab initio calculations of the properties of solids, where the challenge is to introduce the effects of correlations, and also for the simulation of model systems, which allow for the realization of true numerical “experiments” and for which new techniques and algorithms must be developed. It is thus important to have both constant research on that front and powerful computational means (Georges, Giamarchi, Kollath).


64Vortex lattice of MgB2 as imaged by STM. (Credit: UNIGE, Ø. Fischer)


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3. Instrumentdevelopmentandapplication

Several novel experimental tools presently used worldwide were invented by members of the University of Geneva’s Department of Condensed Matter Physics (DPMC—Département de Physique de la Matière Condensée) and Materials with Novel Electronic Properties (MaNEP). This know-how accumulated over the past couple of decades is a valuable asset for the application of and further development in quantum materials that shall emerge over the next 20 years, positioning the new Center decisively at the forefront of this fast moving fi eld. The most important contributions to this fi eld by members of the Center include:

- the realization of the fi rst piezoelectric drive to approach sample and tip with nanometer control in an ultrahigh vacuum within the confi ned space of a superconducting coil at low temperature (Fischer, Renner)

- the fi rst realization of photon-spin selective spectroscopy down to 0.1 meV (van der Marel)

- the invention of BaZr03 as the ideal crucible for single crystal growth of high-Tc materials (Flukiger)

- the evaluation of a 5 kWp photovoltaic hydrogen production and storage installation for a residential home in Switzerland (Yvon).

The arena of novel spectroscopic tools comprises a huge and continuously growing family of experimental techniques based on absorption, emission, scattering, or inelastic scattering of neutrons, electrons or photons off a material (photon in, photon out), or crossed techniques such as photo-electron spectroscopy (photon in, electron out), its inverse (electron in, photon out), and so on and so forth (van der Marel, successor Yvon). Atomic scale probes, such as scanning tunneling microscopy (STM), atomic force microscopy (AFM), near fi eld scanning optical microscopy (NSOM) and their derivatives, enable a distinctive insight into materials and device properties. In addition to high-resolution imaging of surfaces all the way to single atom

resolution, these probes can simultaneously measure a broad range of physical properties (electronic, magnetic, optical, elastic, etc.) with equal exquisite spatial resolution. Since their inception in 1981, the family of scanning probes has seen remarkable growth, with increasingly versatile and effi cient sensors. They have established themselves as a prime technique to examine electronic materials. The most remarkable advancements include spin resolved STM and AFM, momentum resolved tunneling spectroscopy (also known as Fourier Transform STM, or FT-STM), atom tracking temperature-dependent measurements, single atom manipulation and true atomic resolution AFM. Scanning probes have given the scientifi c community an unprecedented grip on materials at the single atom level in real space. Very recently, chemical sensitivity has been demonstrated at the single atom level, both by STM and AFM. So far, only a handful of elements on specifi c substrate have been unambiguously identifi ed. But this is an extremely promising research effort, changing the ability to relate local properties to the local, atomically resolved chemical composition. Further STM/AFM developments are under way to access a broader spectrum of electronic properties, such as the spin and orbital confi gurations (Renner).The fi rst aspect of a material when it is processed by the eye is its optical appearance as revealed by the color, transparency and brilliance. The art of characterizing optical properties on a quantitative basis belongs to the domain of optical spectroscopy. For physicists the term “optical” refers to photons of any kind (photons are the elementary particles underlying electromagnetic waves) and may thus indicate microwaves, infrared, visible, ultraviolet or even X-rays. On a fundamental level, optical spectroscopy is used to study the behavior of the elementary particles from which materials are formed (electrons, nuclear particles), allowing for a link between optical appearance and seemingly unrelated properties of a material, such as electric conductivity or heat transport. Spectroscopy at timescales on which the atoms move within a molecule (some hundreds of femtoseconds) not only allows for the understanding of their dynamics (as a “molecular movie”) but also for the control of


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their motion. In particular, quantum control has proved efficient for selectively breaking bonds, forcing molecules in preferred relaxation pathways, and distinguishing between molecules that exhibit almost identical spectra. In the future, the time resolution will be extended to even shorter times in order to access the dynamics of the electrons in the molecules as well, with potential applications such as understanding charge transfer processes in the first steps of light harvesting biosystems (van der Marel, Wolf).An important role is played by spectroscopic tools using fast neutrons and synchrotron radiation. In particular DPMC and MaNEP researchers work in the domain of resonant inelastic X-ray scattering and neutron scattering for research on magnetic excitations, quantum magnetism, and the role of magnetic (spin and orbital) fluctuations in the mechanisms of superconductivity. Excellent collaborations with the Paul Scherrer Institute, ESRF—the European Synchrotron Radiation Facility—and other big user facilities exist on infrared, X-ray and neutron beamlines, and further fruitful scientific collaborations will continue to play an important role for this research program (successor Yvon, van der Marel).

4. Conclusion

The development, exploration and exploitation of novel classes of quantum materials (including superconductors, quantum magnets and low-dimensional materials) is at the heart of this research and training program by some ten world leading research groups. The new Center creates important opportunities for collaboration, and represents a versatile environment where creative ideas will flourish. It also presents a stimulating environment where students come into contact with the rapidly evolving research environment of quantum materials, and where a brilliant idea can lead even a small research group to spectacular discoveries. The theme involves all the main aspects of materials science, ranging from theoretical modeling and high-performance computational techniques, through the development of new materials, interfaces, state of the art experimental techniques and the development of new methods, to applications for industry and society.


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1. Behnia, K., D. Jaccard, J. Flouquet, 2004: “On the thermoelectricity of correlated electrons in the zero-temperature limit”, Journal of Physics: Condensed Matter 16, 5187.

2. Bouquet, F., Y. Wang, R.A. Fisher, D.G. Hinks, J.D. Jorgensen, A. Junod, N.E. Phillips, 2001: “Phenomenological two-gap model for the specifi c heat of MgB2”, Europhysics Letters 56, 856.

3. Craciun, M.F., S. Russo, M. Yamamoto, J.B. Oostinga, A.F. Morpurgo, S. Tarucha, 2009: “Trilayer graphene is a semimetal with gate-tunable band overlap”, Nature Nanotechnology 4, 383.

4. Daley, A.J., C. Kollath, U. Schollwöck, G. Vidal, 2004: “Time-dependent density-matrix renormalization-group using adaptive effective Hilbert spaces”, Journal of Statistical Mechanics: Theory and Experiment P04005.

5. Erb, A., E. Walker, R. Flükiger, 1995: “BaZr03: the solution for the crucible corrosion problem during the single crystal growth of high-Tc superconductors REBa2Cu307”, Physica C 245, 245.

6. Georges, A., G. Kotliar, 1992: “Hubbard model in infi nite dimensions”, Physical Review B 45, 6479.

7. Georges, A., G. Kotliar, W. Kraut, M. J. Rozenberg, 1996: “Dynamical mean-fi eld theory of strongly correlated fermion systems and the limit of infi nite dimensions”, Reviews of Modern Physics 68, 13.

8. Giamarchi, T., P. le Doussal, 1996: “Moving Glass Phase of Driven Lattices”, Physical Review Letters 76, 3408.

9. Giamarchi, T., A.M. Tsvelik, 1999: “Coupled ladders in a magnetic fi eld”, Physical Review B 59, 11398.


10. Hollmuller, P., J.-M. Joubert, B. Lachal, K. Yvon, 2000: “Evaluation of a 5 kWp photovoltaic hydrogen production and storage installation for a residential home in Switzerland”, International Journal of Hydrogen Energy 25, 97.

11. Hossain, M.S.A., C Senatore, R. Flukiger, M.A. Rindfl eisch, M.J. Tomsic, J.H. Kim, S.X. Dou, 2009: “The enhanced Jc and Birr of in situ MgB2 wires and tapes alloyed with C4H6O5 (malic acid) after cold high pressure densifi cation”, Superconductor Science and Technolology 2, 095004.

12. Le Tacon, M., A. Sacuto, A. Georges, G. Kotliar, Y. Gallais, D. Colson, A. Forget, 2006: “Two energy scales and two distinct quasiparticle dynamics in the superconducting state of underdoped cuprates”, Nature Physics 2, 537.

13. Maggio-Aprile, I., Ch. Renner, A. Erb, E. Walker, Ø. Fischer, 1995: “Direct Vortex Lattice Imaging and Tunneling Spectroscopy of Flux Lines on YBa2Cu3O7”, Physical Review Letters 75, 2754.

14. van der Marel, D., H.J.A. Molegraaf, J. Zaanen, Z. Nussinov, F. Carbone, A. Damascelli, H. Eisaki, M. Greven, P.H. Kes, M. Li, 2003: “Quantum critical behaviour in a high-Tc superconductor”, Nature 425, 271.

15. Meul, H.W., C. Rossel, M. Decroux, Ø. Fischer, G. Remenyi, A. Briggs, 1984: “Observation of Magnetic-Field-Induced Superconductivity”, Physical Review Letters 53, 497.

16. Molegraaf, H.J.A., C. Presura, D. van der Marel, P.H. Kes, M. Li, 2002: “Superconductivity-Induced Transfer of In-Plane Spectral Weight in Bi2Sr2CaCu2O8”, Science 295, 2239.

17. Oostinga, J.B., H.B. Heersche, L.Liu, A.F. Morpurgo, d L.M.K. Vandersypen, 2008: “Gate-induced insulating state in bilayer graphene devices”, Nature Materials 7, 151.

18. Renner, Ch., B. Revaz, J.-Y. Genoud, K. Kadowaki, Ø. Fischer, 1998: “Pseudogap Precursor of the Superconducting Gap in Under- and Overdoped Bi2Sr2CaCu2O8”, Physical Review Letters 80, 149.

19. Reyren, N., S. Thiel, A.D. Caviglia, L. Fitting Kourkoutis, G. Hammerl, C. Richter, C.W. Schneider, T. Kopp, A.-S. Rüetschi, D. Jaccard, M. Gabay, D.A. Muller, J.-M. Triscone, J. Mannhart, 2007: “Superconducting Interfaces Between Insulating Oxides”, Science 317, 1196-1199.

20. Triscone, J.-M., Ø. Fischer, O. Brunner, L. Antognazza, A.D. Kent, M.G. Karkut, 1990: “YBa2CU3O7/PrBa2Cu3O7 superlattices: Properties of Ultrathin superconducting layers separated by insulating layers”, Physical Review Letters 64, 804–807.

21. Tybell, T., P. Paruch, T. Giamarchi, J.-M. Triscone, 2002: “Domain Wall Creep in Epitaxial Ferroelectric PbZr0.2Ti0.8O3 Thin Films”, Physical Review B 89, 097601.


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ThEmE 5.From particles to the cosmos

Participants in this theme (status 2011):Alain Blondel, Allan Clark, Thierry J.-L. Courvoisier, Ruth Durrer, Giuseppe Iacobucci, Michele Maggiore, Marcos Mariño Beiras, Marzio Nessi, Daniel Pfenniger, Martin Pohl and Daniel Schaerer

Our understanding of the universe is both precise and completely unsatisfactory. We have measured with unprecedented precision the content of the cosmos and understand preciously little about the components we have detected. There is 70% “dark energy”, 26% “dark matter” and 4% baryons. Dark energy is merely a word describing the cause of the apparent acceleration of the cosmic expansion, while dark matter is only observed indirectly through its gravitational pull. We also know that complex structures (galaxies and clusters thereof) emerged from the almost uniform early universe, whose evolution we know how to describe to some extent. It is assumed that they emerged from the small fl uctuations that are measured in the cosmic microwave background. Interestingly, black holes and galaxies seem to have grown in a very similar way as the universe evolved.

The question of the nature of matter is also addressed through observations made with accelerators. The LHC - Large Hadron Collider - at CERN outside Geneva, is now giving a string of results. Neutrinos are being investigated vigorously now that they have been observed to have mass. And the structure of the theory that subtends our understanding of matter and gravitation is studied in order to not only understand the properties of the particles we know and the nature of dark matter, but also to understand the four fundamental forms of interaction, and provide a unifi ed view of strong and electro-weak interactions on one side and gravitation on the other.

Physics in extreme conditions is observed in the universe where, for example, matter exists at densities higher than the nuclear density in neutron stars. Particles are found at macroscopic energies (1020eV) and move in strong gravitational fi elds close to black holes. Research in Geneva proceeds along all the lines mentioned above. The Center will provide a unique opportunity to bring geographically separated groups to a common location and to increase the interactions between all the actors of this very active fi eld.


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1. Cosmology

Cosmology is one of the threads that lead to understanding the nature of matter; it has developed in Geneva over the last 20 years, both theoretically and through observations. The studies performed in Geneva include the understanding of dark matter in our galaxy (Pfenniger), observations of the most distant galaxies in the universe (Schaerer), modeling of the first stars and galaxies in the universe (Meynet, Schaerer), the cosmic microwave background (CMB), the problem of dark energy and studies of the universe in higher dimensions (Durrer). The Center will pursue cosmological studies in the coming years along a number of paths, all interrelated.

The history of the universe starting from the earliest times will be studied theoretically and observationally. The theoretical efforts will include understanding the relics from the inflation

Computer simulation of the formation of galaxies and galaxy clusters in a cosmological context. The gravitational instability rapidly leads to a network of fragmenting filaments in which each dot has the size of a galaxy.(Credit: UNIGE, Y. Revaz)

time in terms of a 3-branes moving in a higher dimensional space (Durrer), all the way up to a study of the emergence of structures as we see them now (Pfenniger). The way in which structures form in the universe is strongly dependent on the nature of dark matter. This link will be exploited to deduce the properties of dark matter (Durrer, Maggiore, Pfenniger). Once structures are formed, a large part of the understanding of the cosmos and its structure comes from the study of galaxies, the inter-galactic medium and active galactic nuclei (AGN) at very high redshift. This study provides scientists not only with a history of AGN, galaxies, their gas, and their early stars, but also allows them to study the interplay between the different constituents of the universe.

Furthermore, deep multi-wavelength surveys of the universe have started to probe its early history, in particular cosmic reionization, the phase where first light (stars and galaxies) lifts the “cosmic fog” from the neutral hydrogen prevailing in the inter-galactic medium 300,000 years after the Big Bang. New observational facilities, such as the James Webb Space Telescope (JWST) and the European Extremely Large Telescope (E-ELT) will provide an unprecedented look into the first galaxies and the sources of cosmic reionization. Complementary to those, the Atacama Large Millimeter Array (ALMA) and other future infrared/sub-millimeter (IR/sub-mm) missions (e.g., SPICA – the Space Infrared Telescope for Cosmology & Astrophysics) will allow scientists to study gas and dust – the fuel for star formation—at high redshift in depth. At somewhat lower redshift, large galaxy surveys such as those to be carried out with EUCLID, a European Space Agency satellite with the primary goal of mapping the geometry of the dark universe, will constrain the nature of dark energy with unequaled precision and will deliver other important legacy science, provided that this important mission is selected by ESA – European Space Agency – authorities. Several groups (Courvoisier, Durrer, Schaerer) will participate in the development of these space missions and ground-based facilities, will take a variety of roles, including leadership positions in a number of projects, and will exploit the results, both observationally and with theoretical efforts.


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While this is being done within the framework of general relativity, the Center will also investigate whether the Friedman-Lemaitre approach to the metrics of the universe can or possibly should be modifi ed, for example by considering that the universe is not homogeneous at small and medium scales. It may also prove fruitful, or even necessary, to reconsider general relativity when applied to the largest dimensions accessible to observation (Durrer). This approach may lead us to reconsider the existence and the properties, and hence the nature, of dark energy (Durrer).In the coming years scientifi c knowledge will not only advance along the lines that emerged in the last years, it will also be confronted with new and unexpected observational results, models and theories. This is true in the fi eld of cosmology, but also at accelerators and in the fi eld of high-energy astrophysics. Bringing intellectual resources closer together will ensure that the capability to react to these new fi ndings will be optimized. Interestingly, in the past years the new developments have systematically brought cosmologists, particle physicists and high-energy astrophysicists closer together. The new Center is, therefore, very timely, if not urgently needed.

2. Particlephysicsataccelerators

Experimentation at particle accelerators and colliders has been responsible for the vast majority of progress in particle physics in the past decades. The reason is simply that this method allows for the production of particles and thus to study their interactions under controlled conditions that can be systematically varied. The ingredients of matter, quarks and leptons, have been discovered and found to form a “periodic system”, the regularities of which can be understood in terms of simple principles. Electromagnetic, weak and strong forces have been elucidated, their strength and distance laws established. This has required several generations of accelerators, state of the art particle detection technology and international collaborations, which have grown over time from a handful to several thousand members per experiment.Members of the DPNC – the Department of Nuclear and Particle

Physics – at the University of Geneva have actively contributed to major discoveries during this period. Examples are:

• the discovery of weak neutral currents in the Gargamelle neutrino experiment at CERN (Blondel, Pohl)

• the discovery of the W and Z boson at the CERN (Centre Européen pour la Recherche Nucléaire; the European Organization for Nuclear Research) Sp S collider (Clark)

• fi rst direct evidence for the gluon in experiments at the Positron-Electron Tandem Ring Accelerator (PETRA) collider at the Deutsches Elektronen-synchrotron (DESY, the English German Electron Synchrotron, the largest center for high-energy particle-physics research in Germany) (Bourquin, Pohl)

• the fi rst direct observation of hadronic jets from parton fragmentation in hadronic collisions at the CERN Sp S Collider (Clark)

• precision measurements of the properties of the standard model of electroweak and strong interactions with the LEP (Large Electron Positron) experiments at CERN (Blondel, Bourquin, Extermann, Pohl)

• discovery of the top quark at the Fermilab Tevatron collider (Clark)• the establishment of neutrino oscillations in the K2K - KEK

( japanese national high-energy physics laboratory) to Kamioka experiment (Blondel).

All of these groundbreaking experiments have required an intensive accelerator and detector development program to make new technologies available and to cope with the ever increasing amount of data produced by modern experiments. The DPNC has gained a leading position in the application of silicon detection technologies to measurements of charged particle trajectories, as well as the application of scintillating materials to the detection and energy measurement of photons. It also has solid expertise in the fi eld of high-speed data acquisition.

With all the qualitative and quantitative successes of the past, a number of pressing questions remain. These include:

• Is the known spectrum of elementary matter particles indeed complete?

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• What explains the vast hierarchy of masses observed and what is the origin of mass in general?

• Which is the physical mechanism that distinguishes matter from antimatter, and how can the apparent asymmetry between them in the visible universe be explained?

• How can gravity be incorporated at the quantum level?

Given answers to such questions, one might dream of a new standard model, more complete than the existing one and pointing the way to a grand unification of matter and forces, a microscopic approach to the functioning of the universe.

Interestingly, looking at the nature of particles in theoretical physics in the frame of the string theory has led to fascinating results and a new research direction in pure mathematics. This has been driven by considering physical ideas and theories, like quantum field theory, and deriving new concepts in branches of mathematics, such as algebraic geometry and differential topology (Marino). The Center will pursue this line of reasoning and scientists expect to gain a much deeper understanding of the relation believed to exist between the gravitational and the quantum descriptions of the world.

To attack the domain of the unknown, the Swiss particle physics community, organized in the Swiss Institute of Particle Physics, has agreed on a road map identifying the priorities in its experimental program over the next decade. It identifies three high priority pillars: experimentation at the high-energy frontier, experimentation with neutrinos, and astroparticle experiments (see below for the latter). Research at DPNC is fully integrated into this context and always privileges collaboration with CERN in all domains.In the coming 20 years, results at very high energies will be dominated by the outcome of the LHC experiments. Geneva physicists (Clark, Iacobucci, Pohl) form a single large group, representing about half of the DPNC scientific personnel, analyzing data from the ATLAS experiment (A Toroidal LHC ApparatuS, a particle detector experiment at CERN). The main thrust of the analysis in the short term is to gain further insight

Event recorded in the ATLAS detector at the LHC. (Credit: ATLAS collaboration, CERN.)

into the properties and production mechanism of the top quark, which, due to its high mass, is a unique laboratory for the study of strong and electroweak interactions, and look for deviations from current understanding. The top quark is fundamental to the search for new high mass particles. In the longer term, these studies will obviously evolve into a broader spectrum of subjects, including the search for new forms of matter and new forces.LHC experiments will require several upgrades and replacements of equipment damaged by radiation on the way to the ultimate collision rate and energy goals. The Geneva ATLAS group is fully integrated in all stages of this upgrade program (Clark, Iacobucci, Nessi, Pohl) and intends to play an important role, especially for the innermost parts of the tracking detector. This requires maintaining and developing the technical groups and workshops of the Center so as to ensure design and manufacturing capabilities in sync with modern particle detection technology.The way forward beyond the LHC era will depend on the direction indicated by the findings at LHC itself. Should new physics at a scale below a teraelectron volt (TeV) be established, conventional linear electron-positron colliders may suffice to further study the processes involved. If the scale is observed to exceed this boundary,


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Event on the very close detector at T2K experiment. (Credit: UNIGE, A. Blondel)

new acceleration principles such as used in the CERN two-beam accelerator CLIC (Compact Linear Collider) must be developed if technically feasible. It may be that the most viable way forward will be to increase LHC collision energy, with the development of higher fi eld superconducting magnets. As far as novel detectors for such colliders are concerned, DPNC physicists (Pohl, Blondel) are involved in the design effort, coordinated on a European scale in the EUDET: Detector R&D towards the International Linear Collider and Advanced European Infrastructures for Detectors at Accelerators (AIDA) projects supported by the European Commission.As far as accelerator neutrino physics is concerned, DPNC physicists (Blondel) are taking the leading role in the T2K (Tokai to Kamioka, Japan) experiment, a long baseline neutrino oscillation experiment in Japan. Its main aim is to fi nd positive evidence for and measure the rate of oscillations from muon to electron neutrinos (complementary to existing evidence for neutrino disappearance and the oscillation of muon to tau neutrinos).A long-term program aims to establish if the neutrino mixing-matrix, like the one for quarks, allows for a CP violating phase of observable size. This requires very high intensity proton beams, as well as effi cient techniques to limit the phase space of produced

neutrino beams. To this end, the muon ionization cooling experiment (MICE) at Rutherford Appleton Laboratory (RAL) and the NA61 experiment at CERN serve to measure the basic properties of high-intensity beams and secondary particles. Again, the DPNC group contributes tracking detectors, calorimeters, data acquisition and analysis expertise to all of these efforts. The long-term aim is to fi rst construct a high-intensity neutrino beam from CERN to a location 2,000 km away, together with detectors at each site. In a second step, a neutrino factory with even higher beam intensity and more sensitive detectors can be envisaged.

3. High-energyastrophysics

Work in high-energy astrophysics has been active in Geneva since 1988, starting with the study of quasars for which Courvoisier developed models to explain the way in which gravitational potential energy is radiated by electrons and confronted these ideas with observations covering the entire electromagnetic spectrum. This effort grew with the exploitation of ESA’s International Gamma-Ray Astrophysics Laboratory (INTEGRAL) satellite, for which the Data Centre for Astrophysics (ISDC) was created. The ISDC is responsible for the receipt, processing, archiving and distribution of INTEGRAL data for the astronomical community worldwide. This has led to strong development in the study of compact objects and the discovery of, for example, compact sources deeply embedded in cocoons of matter (Courvoisier and ISDC staff).Looking at the universe with gravitational waves will be complementary to what can be learned from electromagnetic radiation. This is still to come, but efforts started long ago in this direction, with Geneva physicists participating already for a number of years (Maggiore).The structures that are formed in the universe include galaxies and clusters of galaxies, but also, from very early on, black holes. The mass of black holes is closely related to the mass of galaxies, illustrating the deep (and rather unexpected) ties that black


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2 The scientific ambitions II The scientific ambitions

Cosmic ray detector AMS attached to the international space station. (Credit: NASA).

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hole and galaxy evolution have. The Center will examine this link through the study of activity in galaxies (Courvoisier). The Center will also pursue the attempt to understand in general how the potential gravitational energy released by baryons being accreted in the potentially deep well of compact objects is transformed into radiation emitted by accelerated electrons (Courvoisier).The environment of black holes is the place where a number of gravitation tests can be performed by studying the light emitted (in particular line profi les) in the X-ray domain and the gravitational waves that are generated in binary systems of compact objects (black holes or neutron stars). This study will be pursued both with space instruments (LISA, IXO, ASTRO-H, POLAR, etc.) and on the ground (LIGO, VIRGO, Cerenkov Telescope Array) (Courvoisier, Maggiore, Pohl).The high-energy particles accelerated from different sites in the universe emit light when they interact with magnetic fi elds and/or with ambient radiation. This allows for the observation of energetic particles at the acceleration site. This is done with a large collection of instruments. At the highest energies reachable it is expected that the Cerenkov Telescope Array (CTA) will be a very powerful tool and the Center intends to take an active role in this project and its scientifi c exploitation (Pohl). CTA, together with the other available instruments, allows scientists more generally to gain a considerable understanding of the nature of cosmic high-energy sources like quasars, galactic X-ray binary sources, pulsar wind nebulae. These observations are profoundly modifying the vision of the cosmos. Scientists have come to see, for example, that violent phenomena taking place on time scales as short as a fraction of a second play an important role in shaping the cosmic environment, in strong contrast with the timescales of stellar evolution. The Center will pursue the work on the nature of these cosmic sources and contribute to the observational projects that will improve understanding (Courvoisier, Neronov, Pohl).The very high-energy particles that are observed as cosmic rays are the subject of intense study in order to understand where and how they are accelerated. The Center will exploit the Alpha

Magnetic Spectrometer (AMS) data to the fullest in order to study this question for relatively low-energy particles and to probe whether in the cosmic rays there is a particle signature that could be dark matter (Pohl). At the highest energies the Center expects to be active in JEM-EUSO – Japanese Experiment Module Extreme Universe Space Observatory – an experiment that uses the atmosphere as a whole as a detector (Neronov).


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4. Conclusion

In the coming decade or two astrophysicists and physicists will join their efforts to approach the central questions of the nature of matter, the understanding of fundamental laws, the structure of the universe, and the formation and evolution of its constituents, theoretically, experimentally and observationally. They will use state-of-the-art international facilities and satellites extensively. They will develop new instruments on the ground, in space and for accelerators to increase the observational base of particle and astroparticle physics, providing statistically and systematically accurate measurements. They will develop a common data infrastructure, a truly multi-messenger approach to the cosmos. Theoretical efforts will strive to gain a unified view of particles, gravitation and the cosmos.Geneva physicists are developing CAP-Genève, a center for astroparticle physics that brings all particle physics, astrophysics and cosmology actors that share common interests closer together. This synergy has been developing since 2010 with common discussions of results and collaborations in a number of projects on the ground and in space (PLANCK, CTA, ASTRO-H, EUCLID, POLAR, among others). The Center will allow those working with CAP-Genève to move closer to each other physically, which will help further their endeavors. It will also help the organizations face new and exciting developments in their respective fields.

The central region of our Galaxy as observed in the gamma rays by the INTEGRAL satellite (Walter, ISDC). (Credit: UNIGE, ISDC, R. Walter)


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2. Blondel, A., 2009 : “Neutrino Factory R&D and the International Design Study for the Neutrino Factory”, Proceedings of Science EPS-HEP:282.

3. Bonvin C., R. Durrer, 2011: “What galaxy surveys really measure”, Phys. Rev. D [arXiv:11.05.5280] .

4. Bonvin, C., R. Durrer, M. Kunz, 2006: “Dipole of the luminosity distance: a direct measure of H(z)”, Physical Review Letters 96, 191302.

5. Drukker, N., M. Mariño, P. Putrov, “From weak to strong coupling in ABJM theory’’, to appear in Communications in Mathematical Physics [arXiv:1007.3837 [hep-th]].

6. Durrer, R., J. Hasenkamp, 2011 : “Testing String Theory with Gravitational Waves”, Phys. Rev. D [arXiv:1105.5283].

7. Gentile, S., M. Pohl, 1996 : “Physics of Tau Leptons”, Physics Reports 274 287.

8. K2K Collaboration (Ahn, M.H., et al.), 2006 : “Measurement of neutrino oscillation by the K2K experiment” Phys. Rev. D 74, 072003.

9. Maggiore M., 2008: “The physical interpretation of the spectrum of black hole quasinormal modes”, Phys. Rev. Lett. 100, 141301.

10. Maggiore, M., A. Riotto, 2010 : “The Halo mass function from excursion set theory. III. Non-Gaussian fl uctuations’’, The Astrophysical Journal 717, 526.

11. Neronov A., I. Vovk, 2010 : “Evidence for Strong Extragalactic Magnetic Fields from Fermi Observations of TeV Blazars”, Science 328, 73.

12. Pfenniger, D., F. Combes, 1994 : “Is dark matter in spiral galaxies cold gas? II. Fractal models and star non-formation”, Astronomy & Astrophysics 285, 94.

13. Pfenniger, D., F. Combes, L. Martinet, 1994 : “Is dark matter in spiral galaxies cold gas? I. Observational constraints and dynamical clues about galaxy evolution”, Astronomy & Astrophysics 285, 79.

14. Richard, J.; R. Pella, D. Schaerer, J.-F. Le Borgne, J.-P. Kneib, 2006 : “Constraining the population of 6 ≤ {z} ≤ 10 star-forming galaxies with deep near-IR images of lensing clusters”, Astronomy & Astrophysics 456, 861.

15. Schaerer, D., 2002: “On the properties of massive Population III stars and metal-free stellar populations”, Astronomy and Astrophysics Supplement 382, 28S.

16. Schaerer, D., S. de Barros, 2010 : “On the physical properties of z ≤ 6-8 galaxies”, Astronomy & Astrophysics 515, 73.

17. The MARK-J Collaboration (Barber, D.P., et al.), 1980 : “Physics With High-Energy Electron Positron Colliding Beams With The Mark-J Detector”, Phys.Rep. 63, 337.

18. Türler, M., S. Paltani, T.J.-L. Courvoisier T.J.-L. et al. 1999 : “30 years of multi-wavelength observations of 3C 273”, Astronomy and Astrophysics Supplement 134, 89.

19. Winkler C., T.J.-L. Courvoisier, G. Di Cocco, et al., 2003 : “The INTEGRAL mission”, Astronomy & Astrophysics 411, L1.



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Mathematics plays a central role in our attempts to understand the universe. Over several millennia, mathematics has been used as a universal language to express the laws of nature, and a tool for quantitative predictions, as well as for simple bookkeeping in all possible fields of human activity. The development of mathematics is driven by its internal logic, turning it into a fascinating subject that rivals fine arts in sophistication and creativity.

Mathematics enters our life in many ways. Subjects as diverse as weather prediction, stock market analysis, image processing and global positioning system (GPS) navigation are facets and applications of various mathematical achievements. Mathematics forms the basis of the school education system, and the backbone of the University science program. It provides the best way known to mankind to develop creative and rigorous thinking in all areas of human activity.

Modern mathematics tackles problems triggered by its internal structure (such as the Riemann hypothesis in number theory) as well as by applications to practical problems (such as the search for effective coding algorithms). Some important problems come from other fundamental sciences (such as the mass gap problem in the Yang-Mills theory). Mathematics advanced rapidly throughout the last century, with spectacular achievements and the solving of important problems. This progress has led to new vistas for research, while many old problems remain unsolved, as evidenced by several open problems lists, such as the well-publicized Millennium Problems of the Clay Institute.

The new Center will have the potential to make important contributions to advances in mathematics, especially to the solutions of problems at the interface between mathematics and physics.

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Participants in this theme (status 2011) : Anton Alekseev , Martin Gander , Ernst Hairer , Anders Karlsson , Marcos Mariño Beiras, Grigory Mikhalkin, Stanislav Smirnov, Tatiana Smirnova-Nagnibeda, András Szenes, Yvan Velenik


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1.MathematicaltraditioninGeneva

The University of Geneva has a long-standing tradition of excellence in mathematics. The first internationally renowned mathematician was Gabriel Cramer (1704-1752), who made important contributions to the theory of algebraic curves. Now, all over the world, high school students and first year university students of linear algebra learn Cramer’s Rule, an elegant formula for the inverse of a matrix, which resulted from his research.

Closer to current times, another monumental figure of Geneva’s mathematical history was Georges de Rham (1903-1990). He made groundbreaking contributions to the field of algebraic topology. The de Rham differential and de Rham cohomology are notions that enter all standard mathematics curricula. De Rham influenced the development of the Department of Mathematics in a decisive manner, turning it into a first class, modern research institute.

The University of Geneva’s Department of Mathematics has several established scientific schools that contribute to its international standing and recognition. The most important groups are:

• The School of Geometry and Topology built by André Haefliger and Michel Kervaire - this tradition was continued by Pierre de la Harpe, Jean-Claude Hausmann and Claude Weber ; in particular, Pierre de la Harpe created an active group working in group theory.

Vaughan Jones, a former graduate student of André Haefliger, received a Fields Medal in 1990 for the discovery of a new knot invariant, the Jones polynomial. This invariant led to the creation of a new field called quantum topology.

• The School of Numerical Analysis founded by Gerhard Wanner put Geneva firmly on the map of important centers in applied mathematics.

• The School of Mathematical Physics, founded by Jean-Pierre Eckmann, established a flourishing collaboration between the departments of Physics and Mathematics.

The following describes the main research directions of the department.

2.Mathematicalphysics

One can trace the origins of mathematical physics back to Isaac Newton, who invented calculus in order to solve equations of celestial mechanics. The traditional goals of mathematical physics include creating the mathematical tools needed for the development of physical theories, as well as putting results obtained by observation and by intuitive arguments on a firm basis. Recently, more ambitious tasks have emerged. On one hand, mathematical physics brings general principles and mathematical elegance to physics in competition with theoretical physics. On the other hand, mathematical physics uses the intuitive approach developed in physics to obtain new, unexpected conjectures in pure mathematics.

Nowadays, mathematical physics lies at the intersection of many areas of mathematics: Lie algebras and operator algebras appear in classical and quantum mechanics, probability theory and combinatorics are among the main tools in statistical physics, ordinary differential equations are the language of dynamical systems and chaos theory, fluid dynamics is described by partial differential equations, topology is at the heart of cosmology and quantum field theory, etc.

The Mathematical Physics group of the Department of Mathematics has grown significantly over the last decade, with several world leaders in the field joining the department. Following is a very brief description of the research groups and their main achievements.

The group of Anton Alekseev works on quantization, a still mysterious procedure that lies at the heart of quantum physics. The idea of quantization has had a strong influence on the development of mathematics and mathematical physics. Among the recent achievements of this group are the proof of the Kashiwara-Vergne conjecture in Lie theory (which had been open


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since 1978), as well as the proof of the [Q, R] = 0 (quantization commutes with reduction) conjecture for actions of loop groups.The research groups of professors Stanislav Smirnov and Yvan Velenik study statistical physics. The goal of statistical physics is to derive large-scale properties of macroscopic systems from the description of their microscopic components, using probabilistic techniques. Among recent results are the proof of conformal invariance of the 2-dimensional percolation and of the 2-dimensional Ising model at criticality, the computation of the connectivity constant of the honeycomb lattice, and the development of the Ornstein-Zernike theory. For his contributions, Stanislav Smirnov was awarded the Fields Medal in 2010, the highest honor in mathematics. Thanks to his impact, Geneva has become a world leading center in mathematical physics.The group of Professor Marcos Mariño ( joint position with the Department of Theoretical Physics) focuses on string theory and, in particular, on the concept of holography. Important results of this group include the Marino-Vafa formula, the theory of the topological vertex and the Bouchard-Klemm-Marino-Pasquetti conjecture.The Mathematical Physics group is organizing three research seminars: Physical Mathematics, Mathematical Physics (in collaboration with the Department of Theoretical Physics), and Lie groups and moduli spaces (in collaboration with the Algebra and Geometry group). The Mathematical Physics group is an active link between the departments of Physics and Mathematics, and has close ties with the Theory Division at CERN.The long-term challenges faced by the mathematical physics community include:

• The Clay Millennium Problem on the mass gap in the Yang-Mills theory. In essence, solving this problem would give the first glimpse of a strongly interacting Quantum Field Theory in 3 + 1 dimensions.

• Proving and studying conformal invariance of the scaling limit of 2-dimensional integrable lattice models. Some of the first results in this direction were obtained by Stanislav Smirnov in the case of percolation and the Ising models.

• Trying to find genuinely 3-dimensional integrable models and analyze them.

• Finding a mathematical understanding of Feynman’s path integral, turning it into a regular research tool rather than a mysterious calculational technique.

• Turning the ideas of holography developed within string theory into a mathematically complete picture.

The Mathematical Physics group is taking an active part in the research related to these challenges. In a number of directions (including the scaling limits of 2-dimensional models, and certain aspects of string theory), it is among the world leaders in this very competitive field.

3. Algebraandgeometry

The search for symmetries has been a human endeavor since ancient times. Recent mathematical discoveries have given rise to surprising applications of symmetries in several practical fields of research, such as cryptography (prime numbers), error correcting codes (theory of finite fields), and large efficient communication networks (representation theory of groups).Geneva has a great tradition in algebra and geometry, and in the last few years a new generation of researchers in these areas has joined the department. The profile of the algebra and geometry group includes several branches of algebraic geometry, enumerative geometry and its relations to quantum physics, and group theory with relations to combinatorics and probability theory.Starting with the first topic, professor Grigory Mikhalkin is one of the world’s leading experts in tropical geometry, which is a new and rapidly developing branch of algebraic geometry. This is a novel method to study the geometry of polynomial equations, which, in particular, provides a way to count the number of their solutions. Tropical geometry methods have provided solutions to a number of deep problems in several fields, including combinatorics, enumerative geometry and mathematical physics.

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2 The scientific ambitions

PercolationEach hexagon is colored yellow or white randomly, and the group studies how blue water can penetrate yellow rock from the top line through white holes. Despite its simple description, percolation is an accurate model of many physical phenomena, from forest fires to erosion, and leads to beautiful and complicated fractal structures. (Credit: UNIGE, S. Smirnov)


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Geneva is one of the main research centers in tropical geometry, playing an important role in the development of this dynamic field of research.Enumerative geometry, one of the most ancient parts of geometry, has gone through a revolution during the last two decades as intuition from quantum physics produced a wealth of conjectures in the subject. Two of these high-profile conjectures, the Verlinde formula and Zamolodchikov’s periodicity conjecture, were first proved by Professor András Szenes. His group is in active collaboration with the mathematical physics group.Symmetry is most directly described by the mathematical theory of groups. In Geneva, professors Anders Karlsson and Tatiana Smirnova-Nagnibeda are in particular studying random processes and models from statistical physics on groups. Recently, they obtained a result in percolation theory that shed new light on Dixmier’s half-century old unitarization problem in operator algebras. They have also made important progress in understanding the link between the drift of random walks and the existence of non-constant harmonic functions. This problem, left open by a 1984 paper by Varopoulos, was resolved via the discovery of an unexpectedly general law of large numbers.The knot theory and quantum topology group is directed by Rinat Kashaev. It continues the tradition started by Vaughan Jones during his studies in Geneva. The volume conjecture suggested by R. Kashaev relates the asymptotics of the colored Jones polynomial and the hyperbolic volume of the knot complement. This conjecture is one of the driving forces in the development of quantum topology.The Algebra and Geometry group hosts the research group of Professor Michelle Bucher-Karlsson (funded by the Swiss National Science Foundation), which focuses on interactions between geometry and group theory.The Algebra and Geometry group organizes weekly research seminars: Geometric stories, Groups and Geometry, Knot theory, Lie groups and moduli spaces (in collaboration with the Mathematical Physics group). Historically, the Algebra and Geometry group was the first group created in the department, and it remains

important for the department’s expertise in pure mathematics.

The long-term goals of this group include:

• using tropical geometry to refine algebro-geometric concepts through separation of those phenomena that are affected by a choice of ground field (phase-structures) from intrinsic and universal “tropical” aspects that are independent of such choice;

• developing the theory of Higgs bundles, building a connection between Algebraic Topology, Complex Analysis, Hyperkähler Geometry, Number theory and the Langlands program in Representation Theory;

• improving understanding of amenability of groups, and in particular of the Banach-Tarski paradox, Benjamini-Schramm percolation conjecture, and Dixmier’s unitarizability conjecture;

• using group theory to discover new expander and Ramanujan graphs (these are efficient and economical network designs);

• approaching the abc-conjecture and the Gauss circle problem with the development of new types of heat kernel techniques.

4. Numericalanalysis

Differential equations are a ubiquitous tool for modeling in science and engineering. Over the last three centuries, many important physical phenomena have been successfully described by ordinary and partial differential equations, as it turned out that nature often relates (space and/or time) derivatives of quantities rather than quantities themselves. While the first models were rather simple, the XIXth and the XXth centuries brought substantially more sophisticated differential equations, modeling our world with greater and greater accuracy. For example, weather prediction today would be impossible without solving the Navier-Stokes equations on a regular basis; Maxwell’s

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Influence of wireless networks on the human brain. (Credit: UNIGE, M. Gander and INRA Sophia Antipolis S. Lanteri)

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equations are used to estimate the influence of wireless networks on people and our environment; shallow water equations are important in understanding the formation of tsunamis; and Boltzmann’s equations coupled to magneto hydrodynamics model star explosions.Usually, these differential equations cannot be solved in closed form, and the only practical way to use them passes through numerical simulations.The Numerical Analysis group is developing new numerical techniques for sophisticated differential equation models in science and engineering. A number of contributions have already found their way into applications, for example, in climate and weather simulation (in collaboration with Environment Canada), in tsunami computations (collaboration with the National Center for Atmospheric Research – NCAR) and in the influence of a portable phone on the tissues in the head (collaboration with INRIA – the Institute National de Recherche en Informatique et en Automatique [the French national institute for Research in Computer Science and Control]), in multi-body dynamics and in the simulation of chemical reactions.The group of Professor Ernst Hairer is focusing on the study of numerical methods applied to ordinary differential equations (ODE). In particular, this group is trying to predict the behavior of a system described by an ODE after a very long period of time. For instance, predicting the future of the solar system is a problem of this type.The group of Professor Martin Gander studies domain decomposition and multi-grid methods, and massively parallel algorithms for solving partial differential equations (PDE).The Numerical Analysis group is organizing a research seminar with the same name. The ultimate research goal faced by this group is to achieve a numerical simulator that permits the solution of time-dependent partial differential equations in the same black box way as one solves large systems of non-stiff and stiff ordinary differential equations nowadays, often using numerical techniques and programs developed by the group in Geneva.

The Numerical Analysis group is representing the applied mathematics side of the department. It is also the point of contact with the Computer Science Department of the University of Geneva.

5. Miscellaneous

Mathematical Teaching: The Department of Mathematics hosts one of Europe’s oldest mathematical journals, L’Enseignement mathématique, which has been published since 1899. Despite its name (translated as Mathematical Teaching) this is a research journal that on the one hand publishes original new results, and on the other addresses a wide mathematical audience.Statistics: The Department of Mathematics is responsible for teaching statistics to students of the Faculty of Sciences, and for providing expertise in statistics for researchers working in other fields. Sylvain Sardy and his group are in charge of these two tasks. They also represent the Department of Mathematics in the newly created Ph.D. in Statistics program in cooperation with other faculties of the University of Geneva.Interaction with high schools: Contact with Geneva region high schools is one of the important tasks of the Department of Mathematics. It concerns both recruiting new students and the wider dissemination of mathematical knowledge among the general public. These tasks are taken care of by Pierre-Alain Chérix and his group. This group also makes an active link with the Faculty of Psychology and Sciences of Education at the University of Geneva.

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6. Conclusion

The perspective of integration of the Department of Mathematics within the new Center promises a number of synergies. In particular, the Mathematical Physics group is already working in close contact with theoreticians of the Physics Department. A closer collaboration will allow for the creation of new joint seminars and new opportunities for graduate students and post-doctoral collaborators. For the Numerical Analysis group, there are new and exciting fields of applications for their methods provided by the physicists and astronomers working in fields as diverse as weather prediction and galaxy dynamics.The new Center will further enhance the national and international visibility of the Department of Mathematics. It will create an attractive environment for visitors and students alike.Last, but not least, a closer integration of teaching with the astronomy and physics programs will open new opportunities for students.


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1. Alekseev, A., E. Meinrenken, 2006: “On the Kashiwara-Vergne conjecture”, Inventiones mathematicae 164, 615.

2. Aganagic, M., A. Klemm, M. Mariño, C. Vafa, 2005: “The topological vertex”, Communications in Mathematical Physics 254, 425.

3. Bodineau, T., D. Ioffe, Y. Velenik, 2000: “Rigorous probabilistic analysis of equilibrium crystal shapes. Probabilistic techniques in equilibrium and nonequilibrium statistical physics”, Journal of Mathematical Physics 41, 1033.

4. Bridson, M., A. Haefliger, 1999: “Metric spaces of non-positive curvature”, Grundlehren der Mathematischen Wissenschaften 319, Springer-Verlag, Berlin.

5. Cramer, G., 1750: Introduction à l’analyse des lignes courbes algébriques.

6. Eckmann, J.-P., D. Ruelle, 1985: “Ergodic theory of chaos and strange attractors”, Review of Modern Physics 57, 617.

7. Gander, M., F. Magoulès, F. Nataf, 2002: “Optimized Schwarz methods without overlap for the Helmholtz equation”, SIAM Journal on Scientific Computing 24, 38.

8. Grigorchuk, R., T. Nagnibeda, 1997: “Complete growth functions of hyperbolic groups”, Inventiones mathematicae 130, 159.

9. Hairer, E., S. Norsett, G. Wanner, 1993 : “Solving ordinary differential equations”, I. Nonstiff problems, second edition, Springer Series in Computational Mathematics 8, Springer-Verlag, Berlin.


10. Karlsson, A., G. Noskov, 2002: “The Hilbert metric and Gromov hyperbolicity”, L’Enseignement Mathématique 48, 73.

11. Kashaev, R., 1997: “The hyperbolic volume of knots from the quantum dilogarithm”, Letters in Mathematical Physics 39, 269.

12. Kervaire, M., J. Milnor, 1963: “Groups of homotopy spheres”, I. Annals of Mathematics 77, 504.

13. Mikhalkin, G., 2005: “Enumerative tropical algebraic geometry in R2”, Journal of the American Mathematical Society 18, 313.

14. de Rham, G., 1984: “Differentiable manifolds. Forms, currents, harmonic forms”, Grundlehren der Mathematischen Wissenschaften 266, Springer-Verlag, Berlin.

15. Smirnov, S., 2001: “Critical percolation in the plane: conformal invariance, Cardy’s formula, scaling limits”, Comptes Rendus de l’Académie des Sciences. Série I. Mathématique. Académie des Sciences, Paris 333, 239.

16. Smirnov, S., 2010: “Conformal invariance in random cluster models. I. Holomorphic fermions in the Ising model”, Annals of Mathematics 172, 1435.

17. Szenes, A., 1998: “Iterated residues and multiple Bernoulli polynomials”, International Mathematics Research Notices 18, 937.

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PART III . The Center in Geneva and the World

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Local and world wide collaboration schemes, innovative teaching

programs, scientific outreach through the ScienScope, and a Laboratory

of Advanced Technology making the Center’s expertise available to the

local industry, in addition to world class facilities and scientific research,

are key elements that will ensure a successful and sustainable operation

of the Center for many years to come. The following sections describe

key facilities and services required to accomplish the scientific, academic

and outreach objectives of the Center.

Teaching and education International and national relations

ScienScope Laboratory of Advanced Technology

Science library Services

Introduction

III The Center in Geneva and the World

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The creation of the new Center will have extremely positive effects on the quality of teaching, both at the undergraduate and graduate level. Bringing together the students in mathematics, physics and astronomy will generate a stimulating intellectual atmosphere for the students as well as for the teachers, and will allow the development of many synergies that arise quite naturally between these disciplines. At the logistic level, this will also allow to concentrate courses that are presently scattered among far away locations into a single center.

ThecreationofthenewCenterwillhaveextremelypositiveeffectsonthequalityofteaching,including:

The development of education synergies between the Physics sections and the Astronomy departmentVery similar synergies could also be developed between the teaching of physics and astrophysics. One rapidly expanding research area, which is also a main focus of research in the Physics section, concerns relations between particle physics, astroparticles, astrophysics and cosmology. Today, some courses in this area are offered in the Physics section and others at the Geneva Observatory, some 25 kilometers away. It is the same for seminars of common interest to doctoral students and researchers, and to date there is very little exchange between students who specialize in these research directions at the Observatory, and those who move towards rather similar research in the Physics section. Bringing all these skills together in a single Center would generate an exciting atmosphere for students and doctoral candidates, and would open the door to different modes of interaction between physicists and astronomers, such as joint Ph.D. or Master’s work.With such a range of skills, the new Center could also become a major hub for visitors (students, Ph.D. students, post-doctoral candidates and researchers) at the international level and therefore generate intellectual dynamics modeled on, for example, the Max Planck Institute in Garching or the Kavli Institutes in the United States and elsewhere.Finally, whether in physics or astrophysics, the field of statistics plays an extremely important role in data analysis and the estimation of the reliability of results. The possibility that physicists and astrophysicists have to benefit from the expertise of mathematicians in the teaching of this branch would be an asset for the students.


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Teaching and education

Two examples of physics course rooms, a possible solution combining the group working arrangement (left, MIT), which is state-of-the-art for education and training labs (right). (Credit: North Carolina State University, PER&D Group – WALDNER Labor- und Schuleinrichtungen GmbH, Dresden SCALA)

The teaching of climate physicsAlthough a major center of expertise in research and education in climate exists between ETH-Zurich (the science and technology university) and the University of Bern, the teaching of this important part of the physical environment is missing in Western Switzerland. Through its willingness to support activities in climate physics, the Physics section at the University of Geneva could host an attractive curriculum, and this especially due the proximity of organizations such as the World Meteorological Organization (WMO), which houses the Secretariat of the Intergovernmental Panel on Climate Change (IPCC), and the Geneva offices of MeteoSwiss. A new curriculum may be of interest to these organizations for the creation, and the participation in the creation of, a new generation of students who so far have had to emigrate to other lands in order to perfect their education in the field.It is therefore important that the Physics section of the University of Geneva assume teaching leadership in this area. Initially, a Master’s of Science in climate physics in English could be created to attract foreign students and people working in international organizations who wish to improve their knowledge.

The development of new technologies for teachingReflecting on the evolution of science education 20 years out, one can imagine that an increasingly important role will be devoted to the use of new technologies, both related to the possibility of obtaining qualified information on the web (e.g., specialized courses given by other institutions and available via the Internet) and the development of computer visualization tools and data analysis. One such effort could be made in the visualization of the results of climate simulation work, like what is done in planetariums: 3-D visualization techniques projected on a big screen (such as a planetarium dome); holographic techniques to view results; and possibilities to explore the three spatial dimensions and the time dimension of results in a room equipped for this purpose.As part of the new Center, it would be possible to develop multimedia rooms that would allow for the exploitation of such solutions. It would also be possible to provide more adequate space for student laboratories (practical work), which could become a veritable showcase for the teaching of physics.

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The relationship with secondary educationThe new Center plans to develop a Physics Learning Laboratory (PLL). This is a physics course room design with integrated experimentation and media facilities allowing for a highly active and experiential, technology-rich learning environment, and including strong support for interaction and collaboration. As such, it is based on current research and best practice for active and experiential physics education, such as the SCALE-UP project adopted by the MIT physics department and almost 100 other institutions.Within the new Center, the purpose of the Physics Learning Laboratory would be fourfold:

1. Research evidence shows the benefits of such a classroom design and the underlying instructional principles for teaching to undergraduate physics students in several areas of interest (conceptual understanding, problem solving, attitudes, attrition rates), even in large enrolment courses.

2. It is highly important that future physics teachers be well familiar and experienced with modern equipment and experiments, as well as instructional technology for educational purposes, and moreover that they can be trained to use these. Students will greatly benefit from training classroom situations in such facilities.

3. Beyond initial education, the PLL would offer outstanding opportunities for continuing professional education, again with a whole range of opportunities from training to new development, thus attracting teachers already working and helping to establish close links between the Physics section and schools.


4. Finally, the PLL allows for a strong synergy in physics education between teaching on the one hand and research & development on the other. As mentioned above, the underlying teaching principles are based on empirical research. Conversely, the PLL would offer a very good framework for the individual contributions a physics education group has to make to research and in the field, again within a whole range of activities, including the development of ideas of prospective and working physics teachers, which can be initiated, supported and evaluated, to empirical research proper to pertinent questions of physics education.

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1. Existinginternationalaspects

The existing activities of the Center already have an inherent and crucial international component. First and foremost the Geneva scientists are involved at an individual level with all the international aspects of research: whether in their publications—in the best international reviews of the field; their participation in referrals—grants and proposals of practically every research system in the world or editorial boards of international journals; direct collaboration with colleagues from leading universities worldwide—whether for research or for exchange students; and their participation in international events or rewards at an international level.On a more institutionalized level, the research of the Center will remain connected to a large number of international networks and activities, such as Marie-Curie and European Science Foundation networks, and prestigious and competitive grants from the European Research Council. In addition, the various components of the Center will participate in existing large international collaborations or institutions. This is, for example, the case in high-energy physics with strong involvement in international programs and institutions such as CERN’s LEP, LHC and ATLAS experiments, as well as the AMS astroparticle detector.Large instruments for astronomy or astrophysics are out of the reach of national research bodies. European countries have therefore pooled their resources for decades to create and maintain common research infrastructure, both on the ground and in space. ESO, the European Southern Observatory, develops and operates large telescopes in Chili. Switzerland is a member of this organization and Swiss astronomers make extensive use of the facilities and contribute to the development of its instrumentation. The European Space Agency’s (ESA) scientific program develops, launches and operates scientific satellites for the European space science community. Switzerland is also an active member of the ESA and its scientific program. The corresponding research institutions in Geneva are strongly involved in several ESA programs, in particular with the ISDC


The Centre strives to become a key place for scientists from around the world in the area of astronomy, physics and mathematics. We plan to install an ambitious visitor program in order to support and develop vigorous collaborations at the forefront of research. The Centre shall have an active program to organize workshops and meetings on hot topics at short notice. This program will also stimulate exchange of students at various levels with major international research centres. The scientific exchanges include national and regional research institutions, notably CERN, PSI, the two Federal Institutes of Technology and Swiss universities. Collaborations inside the university of Geneva, especially the Faculties of science and medicine are also part of this program. The Centre will further stimulate and run scientific networks in the research areas relevant to the Centre.

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International and national relations

Data Centre for Astrophysics, where all the data of the INTEGRAL gamma ray satellite are received, processed and distributed to the world community and where involvement in new programs is being planned. Other projects are being developed outside of these organizations, like the AMS particle detector. In this case ad hoc arrangements are put in place by the collaboration. These large facilities, and therefore the associated collaborations, are essential to the development of the corresponding research.In a similar way there is a large involvement concerning climate, both at the level of mathematics and physics, with several international institutions, such as the Meteorological Service of Canada, or via the C3I research group to the Intergovernmental Panel on Climate Change.

2. ProjectedactivityoftheCenter

ResearchIt is important to maintain the highest level of collaboration and visibility of the research done at the Center. This can be achieved by:

• Hiring part-time (around 20%) teaching staff in order to strengthen the activities or create new fields of activity in the Center. Our goal is to create one or two positions per main subject, corresponding to two full professor positions for the Center as a whole.

• A vigorous visitors program supported by the Center. Participants in the program at every level, including professors, young promising professors and graduate students, could come for periods ranging from several weeks to several months. Support corresponding to local expenses and travel (as well as help for housing) should be provided for some 30, 12-month positions to start. In order to have more visibility, some of these positions should be as chairs. This could be the case for a visiting professor position, or for some very special post-doctoral positions.

• An administrative cell, directly linked with the corresponding structure at the University, which can monitor the various

international activities (such as grants, networks, etc.), and if needed help the researcher with tasks that often look like an administrative maze.

ConferencesAs the Center will be involved in cutting-edge research, it must be able to organize weeklong conferences on subjects of high importance, on short notice. The conferences will be held at the Center – an important aspect of this type of activities – which should also increase the visibility of the research done there and ensure adequate contact of its members, especially the most junior ones, with a flow of visitors and international researchers. A program able to support one conference a month for 60-100 participants would be an adequate start. Depending on its success, this program could be gradually heightened. As with visitors, it is important, especially given the peculiar situation of housing in Geneva, that proper infrastructure exist (either housing for the participants, or help find lodgings).Note that longer stays and a more diverse program can prove useful in the long run. It is important, however, to find the proper equilibrium given the fact that several institutes already propose such conferences (Kavli Institute for Theoretical Physics, the Institut Henri Poincaré, the Newton Institute, etc.).

Teaching and outreachIn order to train the next generation of researchers, it is important to ensure the largest possible diffusion of the Center’s knowledge.At the teaching level, the Center will need to fully internationalize the Master’s degree offered in connection with its research. For special topics, the Center could also offer master classes in the form of one-term programs with the participation of international students. At a higher level, the administrative cell must monitor the international networks, schools and programs that could be important for both the Center’s students and for accessing international students. The Center must also actively participate in these networks, schools and programs.

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New materials, where the national research institute NCCR MaNEP – Materials with Novel Electronic Properties – program has shown its leadership for many years, have close links to new developments in chemistry, in particular novel organic materials that can be used in electronics and optoelectronics. These new organic materials have great potential to reduce the cost and electric consumption of electronic devices, as well as for novel applications, such as flexible solar cells. Novel materials will also be a focus of the collaborative work between Physics section and the University of Geneva Hospital to develop advanced prosthesis and dental treatments.On the educational side, several interdisciplinary Master’s degree programs are currently under consideration (biophysics, climate physics, and medical technology, among others) and will be strongly supported by the synergies provided by the new Center. A first example of this synergy is a new pluridisciplinary outreach project called ScienScope, an extension of the very successful MaNEP PhysiScope initiative. The ScienScope will provide schools and teachers with unique access to state-of-the-art research through dedicated experiments.

In a similar way it is important that the Center monitor and, if needed, participate in international outreach activities (for example the EuroPhysicsFun network) to ensure proper outreach at a global level.

3. CollaborationoftheCenterwithotherdisciplinesoftheUniversityofGeneva

By nature, physics and mathematics are linked to other scientific disciplines like chemistry, biology, and environmental and Earth sciences. The new Center will be a unique opportunity to reinforce existing links between these disciplines, along with medicine (University of Geneva Hospital) and social sciences. In particular, closer links between physics, chemistry and biology will emerge through the new national NCCR MUST (National Center of Competence in Research Molecular Ultrafast Science and Technology) and chemical biology, in which common interests are already expressed in the domains of understanding cellular micromachinery at a molecular level, advanced imaging and control of biomolecules and applications to theragnostics (therapy and diagnostics) of medical diseases. For instance the control of neurons and optogenetics are groundbreaking fields in which these scientific disciplines at the University of Geneva, including the University of Geneva Hospital, have the potential to reach the final goal of the treatment of neuronal diseases like Parkinson’s and Alzheimer’s, or autism.

The physics of climate and the environment, already present today through a collaboration between the Physics section and the ISE (Institut des Sciences de l’Environnement – the Institute of Environmental Sciences), will greatly benefit from the new organization, with possible applications such as the modelization of extreme meteorological events like heavy thunderstorms and floods.

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Science1Systematic knowledge of the physical or material world gained through observation and experimentation; a branch of knowledge or study dealing with a body of facts or truths systematically arranged and showing the operation of general laws.

Scope1Extent or range of view, outlook, application, operation, effectiveness; space for movement or activity; opportunity for operation; aim or purpose; to look at or over; examine; check out.

1 Definition from The oxford english dictionary online

The ScienScope is, in the broadest sense, the interface between the scientific research of the Center and the general public in Geneva and further afield, the entry point to seeing, experiencing and learning everything from basic scientific concepts to the results of current and future cutting-edge research. The ScienScope aims to improve scientific literacy by sharing a passion for science, with focused teaching modules targeted at middle school and high school students, science/art exhibitions, evening conferences and debates on current scientific issues, a pedagogic media library/café, and a virtual platform allowing direct interaction between researchers and the public as part of its offerings.More generally, the Center offers these designated exchange areas, real or virtual, as well as specific outreach events. It also aims at being an interface or information conduit, from the general entrance of the Center, throughout the corridors, galleries, café and all publicly accessible spaces that can potentially be used.


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1. TheScienScopeasaninterface

Science/learning• Interactive laboratories in physics, math, chemistry and life

sciences integrated with the Geneva school curriculum• Weekly evening seminars and debates on current scientific

topics• Public conferences and colloquia• Astronomy/planetarium presentations

Science/culture• Temporary exhibitions in collaboration with Geneva or

international museums• Outdoor exhibits integrating gardens and surrounding city

neighborhoodsScience/food

• Café-restaurant open to the public centered on the concept of “science” in food

Science/outreach• Café/media library focused on making popular science media

accessible to families and school students• Organization of scientific events and open days at the Center• Laboratory visits, viewing galleries open to the public• Virtual ScienScope platform

Science/Industry• State-of-the-art audio-visual projection space for secure

biotech, electronics, pharma and other projections

2. ParticipativelearningattheScienScope

The focal point of the ScienScope, its interactive laboratories, will offer thematically focused teaching modules, designed in collaboration with teachers from Geneva’s public schools, in physics and astronomy, math, chemistry and life sciences. The modules will begin with elementary concepts studied in the

ScienScope

school curriculum, and move through hands-on demonstrations towards more advanced ideas explored in the context of current research. The presenters will be students actively working in the University of Geneva research laboratories, whose youth, diversity and enthusiasm help to dispel many stereotypes about working scientists. The unique advantages of this approach are the participative learning process, and the close link between the University of Geneva teaching and research and the city.

To further promote science education, the ScienScope activities will also be integrated with the IUFE (Geneva’s University Institute for Teacher Training) science teacher training program. In particular, student teachers will participate in the development of the teaching modules and the presentations. Follow-up material developed in collaboration with the IUFE will provide additional value and allow classes to extract the maximum from a ScienScope visit. The ScienScope in turn will provide a unique opportunity as part of the Science Learning Laboratory concept (see also the chapter on Teaching and Education). IUFE could carry out continued monitoring and analysis of the success of the program, developing evaluation tools/questionnaires to gauge the effectiveness of different approaches, thus making the ScienScope itself an object of study and a testing ground for new teaching methods and ideas.

In terms of broader outreach actions, with increased, semi-professionalized manpower the Center could further expand the ScienScope activities to the general public, including sessions during the weekend, and rapid reaction modules to current events. In addition, short “Colonie de Sciences” (science camp) summer stays could be envisaged. On the weekend, the ScienScope could be integrated with existing successful outreach by the University, for example as host of activities like the “hôpital de nounours” (teddy bear hospital), “microbiology days”, and “supra-quoi?” organized by the Faculty of Medicine, and the Biology and Physics sections at the Faculty of Science, respectively.

The Interactive Laboratories are broadly modeled on the current PhysiScope, and upcoming ChimiScope, the public interface of the Physics and Chemistry sections, whose equipment, personnel

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Entrance/reception/exhibitionAs the gateway to the Center, the ScienScope will be its entry point, reception and exhibitions, acting as a window open to the city. The key issues are openness, a welcoming atmosphere and access at all levels—including permanent researchers and students, scientific and industrial visitors to the Center, and the Geneva public. This prime interaction and communication space could include classical or innovative technology information panels and posters on walls, overhead art and science installations, and dedicated exhibition space. An important connection to the rest of the city could be provided by temporary exhibits designed in collaboration with Geneva museums, addressing for instance the historical aspects of science, the role of science in the city life and development, or artistic perceptions of recent scientific discoveries and achievements.

Passageways/galleries/corridorsThese spaces continue the idea of an interface at multiple levels. Public access galleries and passageways can be a continuation of the interaction, exhibition and communication spaces of the entrance. Selected viewing points could allow a continuous real-time window into modern scientific research, while passageways to specific laboratories could be used for more specialized presentations of ongoing results.

Café-restaurantOpen to the public as well as the researchers and students of the Center, the café-restaurant would facilitate encounters and conversations in an informal setting, possibly using the interior or the food itself as an original concept of “science food / food fusion / molecular cuisine” to attract the public. Exhibitions and special events can also be organized in this space.


and expertise will be directly transferred to the ScienScope. The PhysiScope is a public lab housed within the teaching and research facilities of the University of Geneva, with an interactive teaching program developed in collaboration with teachers from the Geneva Department of Education (DIP) and the Télévision Suisse Romande. With a continually evolving and varied subject offering, and animated by a team of graduate and undergraduate students from the Physics section, the PhysiScope leads visitors via “hands-on” demonstrations and experiments from basic physics concepts to their applications at the cutting edge of modern research. During its first 3 years, it welcomed over 8,000 visitors, including students from Geneva and other Swiss cantons, and from Portugal, Finland, Denmark, Holland and France. The PhysiScope is also a partner in the 20 nation EuroPhysicsFun network, using physics to stimulate intellectual curiosity and put the “fun” back in fundamental science learning. Current shows include presentations on force and motion, energy, oscillations, light and color, electricity, magnetism, superconductivity and more. Additional modules integrating astronomy into the presentations are under development. They will remotely access a telescope located at the Gornergrat Observatory, and potentially a smaller telescope on the roof of the Center. In terms of life sciences, a common structure integrating both biology and medicine within the ScienScope presents many advantages, both in terms of public interest and interfaculty collaboration. Both the Biology section and the Faculty of Medicine have extensive outreach programs focused on public events, especially via the BiOutils (biotools) interface. Experiments performed by school classes, continuing education for teachers, conferences and meetings developed in the framework of BiOutils could all be integrated within the ScienScope, while BiOutils scientific study weeks could serve as a model for similar activities in the other fields. More generally, a unified public outreach and school class interface including physics, chemistry, biology, medicine and mathematics will allow much more interdisciplinary modules and approaches to be implemented.

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AuditoriumsA 400-seat auditorium would be used for large public conferences, colloquia and meetings. When necessary, additional University of Geneva space can be used, as for the Wright Colloquia. A 200-seat auditorium would be used for specialized scientific seminars and colloquia or dialogue and debates. A possibility is a weekly public science seminar in the evenings focusing on physics, astronomy and mathematics themes to promote and encourage scientific literacy.

Medialibrary/Café-libraryThis space, aimed at the general public and school students and allowing in-situ consultation of popular science works in an informal atmosphere, and assistance before entry into the main scientific library of the Center, could be used for events for smaller children (reading room/playroom), individual audio-visual displays, and a science boutique.

AdvancedprojectioncenterA round/polygonal room with a 10-12-meter diameter dome, air conditioning, acoustic shielding, and the capacity for telecommunication blackout of Wi-Fi and telephone communications to allow secure projection, this space will be equipped with a digitally controlled projection system (including at least one 3D projection axis, and fish-eye camera for the dome for use as a planetarium). As a link to Geneva industries, this space could be made available to companies requiring secure hi-tech visualization (e.g., of proteins or other molecules, new prototypes). Cutting edge digital control software for the projection system could be developed in collaboration between the informatics and audio-visual engineering departments of the Geneva school of landscaping, engineering and architecture (Haute Ecole du paysage, d’ingénierie et d’architecture de Geneve) and the University of Geneva.

ScienScope

GardensThese will link and open from the Center into the city, and could be used as additional exhibition space (“interactive” artwork centered on physics concepts such as gravity, inertia, energy, in a park area with physics explanation panels) in which the public is an active participant. Long-distance installations can be included in the plans for the neighborhood, such as a walking itinerary of the solar system or exponential representation of size scales from the size of the universe to an electron, perhaps integrated into a nature trail.

VirtualScienScopeplatformThe “ScienScope Geneva” internet portal will allow centralized access to information about all science-related events throughout the city and region both specialized and public. The platform will include a moderated public forum where questions to researchers can be posed, and feedback on scientific issues gathered. Links and listings to Geneva scientific institutions and industries will be accessible. The platform will also provide a teaching area with links and resources for scientific literacy (parent zone, kid zone, frequently asked questions about common misconceptions).

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1.Introduction

The University of Geneva and the University of Applied Sciences (Haute Ecole Spécialisée - HES) are the two major Geneva institutions active in higher education and technology-relevant research. The activities of the two institutions have different targets and follow different approaches. At the University – and more specifically at the Faculty of Science – education and research are mostly driven by fundamental interest. Relevance for applications originates from results that are obtained regularly and have the potential to push forward the limits of existing technology. Work at HES has mainly an engineering character, with the goal of applying more established technology to the solution of technical problems in the development of new applications. These different approaches are complementary and their combination is essential to progress in all areas of advanced technology.

Joint activities on specific projects that involve both Institutions already exist through the initiatives of individual researchers. However, the potential for the use of complementary expertise existing at the two institutions goes far beyond what these individual initiatives can do, and can be fully exploited only by establishing a more structural partnership. Whereas the key objective of such a partnership is clear – to contribute to technological progress by intensifying efforts at the interface between fundamental and applied research – its implementation needs to be planned carefully. The partnership should stimulate common research activities between different groups at the two institutions while preserving flexibility, because the main goals of research – and the requirements of researchers – at HES and at the University of Geneva are different.

As a part of the new Center, the partners propose the creation of ideal settings for a targeted partnership between the University of Geneva and the HES through the installation of a laboratory dedicated to the development of advanced technologies. The initial focus will be on areas where both synergy and direct links to industries already exist. These areas include the fields of micro-fabrication, material


The Center plans to install a Laboratory of Advanced Technology (LAT) representing the first structural, long-term collaboration between the University of Geneva and the University of Applied Sciences (Haute Ecole Spécialisée - HES). To fulfill the ambition of becoming a recognized center for science and technology, the laboratory will be equipped with state-of-the-art instrumentation in the selected areas of activity. It will provide the flexibility to strongly stimulate fundamental and applied research at both institutions, and to combine it effectively with new industrial partnerships. The Laboratory of Advanced Technology will contribute to high-tech activities in the Geneva area by attracting new industrial partnerships, by providing services for companies at competitive conditions, and by exploiting the commercial potential of technology developed in the academic environment through the incubation of start-ups. It will also broaden the educational offer of the University and HES in domains crucial for future technologies.

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Laboratory of Advanced Technology

characterization and metrology, laser machining technology, and electronic applications. To create a top-level center and to facilitate the expansion of research in these fields, the laboratory will be equipped with state-of-the-art instrumentation that is not otherwise accessible. This instrumentation will open new possibilities for both fundamental and applied research, and will provide a strong stimulus for researchers at both Institutions to develop their research activities inside the laboratory. Combining, in a single center, top-end infrastructure and related expertise will have strategic advantages. It will allow researchers at HES and at the University to develop joint projects efficiently in parallel to their own individual research activities. It will also establish a recognized center of competence where high-tech companies will find technical and knowledge support, benefit from different services, and form partnerships for new projects.

The long-term ambition of the Laboratory of Advanced Technology is to become a reference point for science and technology, and to play an important role in their development in the Geneva region. The laboratory will have an impact on education, scientific and applied research, technology transfer, industrial partnerships, services to industry, and the incubation of start-ups. It will enable HES to offer training in new branches of advanced technologies, and will bring University students into contact with companies – an aspect of academic education that is currently insufficiently developed. These possibilities will strengthen the position of HES and of the University on the increasingly competitive “student market”. The benefits for scientific and applied research are obvious. By expanding the scope of research and enhancing the visibility of the University and of HES at all levels – local, national and international – the Laboratory of Advanced Technology will generate partnerships with industries in Geneva, and attract new activities from outside, creating new sources of income. A substantial increase in the number of Swiss Commission for Technology and Innovation CTI1 and EU projects is envisioned, and services provided to industry will be another source. Additional income will originate from the increased number of high-tech workers, scientists and students coming to Geneva.

2. Ambitions

The Laboratory of Advanced Technology is the first example of a structural collaboration between the University of Geneva and the HES. It will be developed with the specific needs of researchers at the two institutions in mind. The laboratory will aim to strengthen the research capabilities of both organizations, and to stimulate areas that have direct technological potential, with the ambition of becoming a key player in the development of technology in the Geneva area. The main targets are to:

• equip a laboratory enabling state-of-the-art scientific and applied research in the areas of interest, with the aim of becoming a top-level facility

• facilitate joint projects between individual researchers at the University and at HES

• maintain the flexibility needed by researchers at the University and at the HES to pursue their respective research goals, while sharing knowledge and infrastructure

• broaden the educational offer in Geneva in technology-driven fields

• become a contact point for industries where technological solutions to problems and technical services can be provided in an efficient and competitive way

• develop and commercially exploit new technologies resulting from research at the University and at the HES, e.g., through the formation of start-up companies

• generate new income by a substantial increase in the number of projects funded by federal (CTI) and European agencies, and by providing services to companies

• stimulate growth in the technology sector in the Geneva area.The strategy needed to reach these targets and a range of requirements are discussed below.

1 Currently the total amount invested in CTI projects in the Geneva area is approximately 10 millions CHF/year, only one-third of approximately 30 million CHF/year invested in the Lausanne or in the Zurich area.

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existing in the Geneva area are in sensing applications (e.g., gas- or bio-sensors), marking, watch-making industry (micro-mechanics – oscillators, low-power sources, low-friction parts), micro-fluidics, devices for medical monitoring.

Material characterization and metrologyThe characterization of a broad range of physical material properties and sensitive analysis of their chemical composition represent core activities both at the University and at HES. The same characterization techniques are also crucial for manufacturing industries in development, diagnostics and quality control. Research at the University of Geneva: The Department of Condensed Matter Physics is the leading house of the National Centre of Competence in Research (NCCR) on Materials with Novel Electronic Properties (MaNEP). It has a long-established expertise and international reputation in the field of material characterization and metrology. The research of all DPMC professors contributes to material characterization and development.Research at HES: HES has established activities in thin-film characterization, including hardness, adhesion, and friction tests. In the development of new high-precision machining systems, metrology and sophisticated dimension measurements are used routinely for design and quality control.Industrial relevance: Infrastructure for physico-chemical analysis and metrology will allow the Laboratory of Advanced Technology to provide services to industries in all sectors (metallurgical, medical, precision mechanics, coatings, etc.), providing an important source of income. Service activities will establish a capillary network of contacts and partnerships with industries.

Laser machiningLaser machining for manufacturing is required for precision mechanics, the realization of mechanical components of complex shapes, and is a powerful technique in different high-tech areas.


3.Researchfocus

The spectrum of research activities at the University and at the HES is broad, and it is strategically important that the focus areas of the Laboratory of Advanced Technology be selected carefully. The focus will initially be on activities of common interest, with technological relevance for industries in the Geneva area.

Micro/nano-fabrication

Important fields of scientific and applied research rely increasingly on the possibility of depositing and patterning materials on small scales – from tens of microns to the atomic scale. The set of techniques that provide material control on these scales is commonly referred to as micro/nano-fabrication. The Laboratory of Advanced Technology will include a clean room and the state-of-the-art instrumentation necessary to implement these techniques. Research at the University of Geneva: Research at the University of Geneva is rapidly expanding. Some of the basic instrumentation is present and nano-fabrication techniques are heavily used to realize electronic nano-structures with novel materials. Expanding the existing infrastructure is essential to developing these directions, which are of long-term strategic importance. Groups involved in other activities (high-energy particle detection, quantum information, optics) also exploit micro/nano-fabrication techniques.

Research at HES: Of current interest for HES are micro-mechanical devices (energy harvesting, filters for telecommunications, new scanning probes) and micro-fluidic circuits for bio-applications. Several projects already exist, but the lack of the required instrumentation represents a severe limitation (micro-fabrication is carried out at the Haute Ecole ARC in Neuchatel). A micro/nano-fabrication facility at the Laboratory of Advanced Technology will bring competences in-house, and give the credibility and the means to HES to participate in many more projects in the domain of nano-technology.Industrial relevance: Key uses related to industrial activities

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Research at the University of Geneva: Lasers are used by several groups at the University – professors van der Marel at DPMC, and Gisin and Wolf at the Group of Applied Physics (GAP) – for research in very diverse areas (spectroscopy, quantum information, weather control). Particularly relevant is the research of Professor Wolf, which combines short laser pulses with very high power levels.

Research at HES: A key activity is the production of high-precision mechanical pieces with improved and controlled surface topology and texture that is playing an increasingly important role in new high-tech applications (e.g., medical sector, space applications, etc.).

Industrial relevance: An important industrial partner in Geneva – already involved in partnerships with the University and the HES on electro-erosion machining – is Agie Charmilles. The Center envisions that the clear potential and flexibility of laser machining (combined with electrical discharge machining) will allow the laboratory to form partnerships with, and provide services to many more industries.

Electronic workshop

Fondamental and applied research constantly require the development of new electronics applications and devices. Groups at the University and the HES have an established expertise, ranging from the implementation of “conventional” control systems to sophisticated and highly dedicated applications. The electronic workshop at the laboratory will maintain contact with all the individual units and allow sharing/centralizing of knowledge, drastically increasing the efficiency of future activities.

Research at the University of Geneva: The activity of all experimental groups requires the development of electronic applications and that substantial expertise be present. In some cases, the expertise is unique and of exceptional level. Examples are activities at the Department of Nuclear and Particle Physics (DPNC) related to the instrumentation needed in high-energy particle physics (e.g., particle detectors, ultra-high speed system control and data transfer) or in quantum information.


Research at HES: In projects where prototypes of new systems are realized, the development of the accompanying electronics represents a significant part of the work. Typical applications include interfaces (e.g., with sensors and computers), feedback control, data acquisition and embedded systems. This electronic instrumentation is mostly designed and assembled in house.Industrial relevance: Most collaborations with industry have as their goal the realization of practical devices, which invariably need electronics controllers. The benefits of having a high-level electronic workshop in-house are obvious. The workshop will also facilitate the realization of prototypes and demonstrators based on new technologies developed at the University or at the HES.

4. VolumeofexistingactivitiesattheUniversityandHES

The focus areas of the Laboratory of Advanced Technology represent a large part of the research activities of the Physics section at the University and of HES. The infrastructure that will be installed in the laboratory will provide a strong stimulus to the existing research of both institutions. This stimulus is of strategic importance for the success of the Laboratory of Advanced Technology, in both the short term (installation period and first operation phase) and in the long term. The possibility to expand their research significantly will attract individual groups at the University and at the HES to use and develop the facilities at the Laboratory of Advanced Technology. Researchers from the two institutions will work on shared instrumentation and face common problems, as is usual in research. Finding solutions to these problems will lead to collaboration on a capillary scale. This “ground-floor” work will be crucial to efficiently setting up the laboratory, and will provide a solid basis for joint research activities. Existing collaboration between individual groups at the University and HES shows that this bottom-up approach is a most effective strategy.To implement this approach, it is important to have a critical

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activity will allow for the establishment of a broad network of industrial contacts.

Many partnerships and collaborations with industries already exist (see list of companies below). The Laboratory of Advanced Technology aims to expand at the national and international level to attract investment from companies and organizations outside the Geneva area.

Companies and institutions already involved in collaborations - or R&D contract work - with either the University or the HES (or both) include: Agie Charmilles, ABB, Sécheron, Bruker, Kugler Bimetal, Merck-Serono, Firmenich, Givaudan, Medacta, Nikon Europe, CERN, European Space Agency, NASA, University of Geneva Hospital, Mavic and Salomon. Collaborations with other important companies – protected by non-disclosure agreements – also exist.

6.Start-upcompanies

Over the past 15 years, several start-up companies have originated from research at the University of Geneva by scientists who ventured to exploit the commercial potential of their work. These companies include Phasis, ID-Quantique, GAP-Otique, AlpesLaser, Ellisis, Luciol, Omnisens, and Suriasis.

One of the goals of the Laboratory of Advanced Technology is to stimulate commercial exploitation of research done in the academic environment through the formation of new start-up companies. The joint presence of University and HES groups – with complementary explorative and engineering research approaches – will strongly stimulate and support these activities.Specific advantages offered by the Laboratory of Advanced Technology to new start-up companies include:

• free availability of laboratory space for the first years of operation• access to state-of-the-art instrumentation (free of charge or

at extremely competitive rates)• ease of access to a highly specialized and flexible work-force

(e.g., HES/University students)


mass of researchers using the infrastructure at the Laboratory of Advanced Technology, and contributing to its optimal functioning. Many research groups at the University and at the HES are strongly interested in the research lines that will be developed in the laboratory and in the advanced instrumentation that will be accessible there. Researchers in these groups will provide the needed critical mass right from the start.

5.Relationtoindustriesandoutsideusers

Both the University and the HES have already established many partnerships with industries in the focus areas of the Laboratory of Advanced Technology. The laboratory aims to substantially increase these collaborative activities. Currently, the in-flow of funds for the University and HES originating from industrial collaboration, R&D contract work, and CTI or EU projects in the focus areas of the Laboratory of Advanced Technology, amounts to approximately 4-5 million CHF/year (this amount does not include projects of purely scientific character – e.g., Swiss National Science Foundation projects – and funds coming through the Center of Excellence MaNEP). A lot of room for an increase in the number of CTI projects is available, since the total investment in these projects in the Geneva area is approximately 10 million CHF/year, only one-third of the same amount in the Lausanne area or in the Zurich area (in both cases approximately 30 million/year). The infrastructure of the Laboratory of Advanced Technology will contribute to enhancing the international reputation of the HES, resulting in a significant increase in the number of EU projects with the HES as partner or coordinator.The Laboratory of Advanced Technology will also perform service work for industries. A main area will be the physical chemical characterization of materials. Laboratories of this type exist, but tend to be overbooked and expensive. The Laboratory of Advanced Technology will offer flexible solutions (e.g., train users to perform their own work) at competitive prices to attract companies. This

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• possibility to find assistance in a broad range of technical and scientific areas

• help in the management of intellectual property• product advertising and contact with relevant industrial

partners (e.g., through the activities of the Geneva Creativity Center, which will have close contact with the Laboratory of Advanced Technology).

The Laboratory of Advanced Technology will also be open to outside start-up companies whose domain of activity will benefit from the expertise and instrumentation available in the laboratory.

7.Contributiontoeducation

The Laboratory of Advanced Technology will enlarge to new areas the educational offer of both the University and the HES.

• Advanced courses will be offered in the field of activities covered by the laboratory, to better qualify engineers educated at the HES in strategic areas for future technologies.

• Students and young researchers will be brought in contact with companies at an early stage of their careers, an aspect of academic education that is hard to emphasize sufficiently.

• Students will have the possibility to carry out projects in new directions of applied research.

• Internships for short-term projects – 6 months to 1 year – in collaboration with industries in all focus areas of the Laboratory of Advanced Technology (to perform feasibility studies, realize prototypes of new devices, etc.) will be available

These initiatives will strengthen the position of the University and HES on the “student market”, and contribute to increasing the number of students who choose to study technological disciplines in Geneva.


8.Nationalandinternationalvisibility

The national and international visibility of the University and HES that will be gained through the Laboratory of Advanced Technology will be beneficial in different ways. The Laboratory of Advanced Technology will:

• create the competence/knowledge and provide the infrastructure to attract new industrial activities to Geneva

• give HES the means and the credibility to apply for European projects

• increase the number of students in Geneva—both at the University and at the HES—thanks to the enlarged educational offer and the tighter contact with industries

• add to the reputation of the University at the international level by providing a top-level facility for research, with state-of-the-art instrumentation

• attract top scientists to Geneva.

9.Outlook

The realization of the Laboratory of Advanced Technology in the new Center creates the ideal setting to establish a focused, structural collaboration between the University and the HES, and represents a unique opportunity. Such collaboration will give an important impulse to research and education at both institutions, and will provide a crucial stimulus to developments in the high-tech industrial sector in the Geneva area. The benefits resulting from research, education and commercial activities that will be developed within the laboratory will have a long-lasting effect.

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Information dissemination changed dramatically about 20 years ago, with the beginning of the Internet age. Science libraries all over the world are striving to introduce delivery and archiving systems in step with these changes. Balancing the introduction of new technologies and maintaining traditional functionalities pose a challenge for any new design of a university library. An interesting example is the Mansueto library at the University of Chicago, to be completed by the end of 2011.The tendency is to remove some of the library materials from the main library halls to archives when these materials are available electronically, to provide access to Internet resources in the libraries, and, at the same time, to maintain and enhance the traditional functions of the library as a place of reflection and scientific research.The University of Geneva is no exception, and a number of services are up and running or are in the pipeline to meet the challenges facing the University in the XXIst century.The library in the new Center will be a unique opportunity to unify, streamline and modernize the access of researchers and students to scientific knowledge.

ImageThe library is the centerpiece of the public image of the new Center. Visitors and students will not necessarily see the new offices and labs, but they will see the library. The library could will serve as the main location for the dissemination of public information: public lectures, prizes, announcements, the display of scientific achievements of the Center, presentations of the components of the University, etc.

WorkspaceThe library will also serve as a workspace and social center for junior researchers, students and visitors who do not have offices of their own. Such space is of key importance in the life of junior researchers in a science center. In particular, the library should include a large number of workspaces of varying styles: desks, couches, groups of chairs, maybe a small café, etc.

SpaceforgroupsThe library will include a small number of soundproof discussion rooms for small groups of students or junior researchers.

CommonlibraryThe Center foresees the unifying of library collections held by the composing units: the Mathematics library, the Physics collection and the Astrophysics library – keeping each collection, however, in separate, well-defined areas of the library. This will represent the unity of the Center, simplify searches, allow the pooling of resources, and create a unifying social space for the Center.

ReadingroomsThe respective departments may create reading rooms in their area, mainly with electronic access: computers, readers, copy machines, etc.


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StaffThe new library will have an increased and specially trained staff readily available to help researchers with their searches. Experience shows that while electronic access has simplified finding materials, the variety of contracts with publishers, the numerous possibilities of inter-library loans, the mechanics of the various delivery services, and ordering of books, among others, require highly competent library staff.

ElectronicaccessMost journals will be electronically accessible and will not be kept at the library. Electronic access will be provided via mobile e-readers and other state-of-the-art media. The library will purchase the rights to archives of the major publishers of interest to the researchers of the Center.

BookcollectionThe University of Geneva has installed or is in the process of introducing an electronic delivery service (scan-and-send) for periodicals with one-hour turnaround time, as well as physical delivery of books from a remote location within a day. Considering that the role of books, the manner of their use, and the time it takes for texts to become obsolete depend a great deal on the domain of research, the exact proportions and ways in which the libraries of the three composing units will participate in these initiatives will depend on the preferences of these units.

Science library

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1.Informationtechnologyinfrastructure

The expected needs in terms of information technology (IT) infrastructure for the totality of the Astronomy, Physics and Mathematics units in the context of the development of the Center are summarized hereafter. The resources required for the whole of the University of Geneva’s Science Faculty have also been considered. However, the inclusion of massive data processing infrastructure in the sense of a national or regional research project has not been considered. History and the current situation have proven that foreseen margins have been overtaken by the actual evolution of the needs of the participating groups. Many of the research and project-related activities of the groups involved rely vitally on an ever growing volume of scientific data. The main data providers are ATLAS (A Toroidal LHC ApparatuS), a particle detector experiment at CERN’s Large Hadron Collider accelerator, the Cerenkov Telescope Array (CTA), a ground-based observatory with global participation currently under development to study the “very-high-energy” universe, and the European Space Agency’s future EUCLID satellite with the primary goal of mapping the geometry of the dark universe.The experimental and observational data need to be transferred from several remote sites to the data center where the data is processed, archived and in general made available to a wide community of scientists around the world.

AssumptionsIn order to arrive at a reasonable estimate, a number of projects currently in operation or under development have been analyzed and the expected needs of data storage and computing power compiled.In doing so, the following assumptions were made:

• the power consumption per installed rack remains at a constant level of some 15kW

• IT equipment purchases follow a 4-year renewal cycle• the electrical power estimates are typical usage value;

margins need to be planned to cater for peak consumption


Research, whether experimental or theoretical, greatly benefits from efficient and outstanding supporting infrastructure. Pushing the limits of our knowledge requires state-of-the art equipment that is not always readily available. Many experimental projects rely on custom designed and home built instrumentation. Easy access to design, machining and building competencies is therefore decisive. Experiments further demand unusual, sometimes extreme environmental conditions. Clean rooms of different grades are needed to assemble a variety of components, from large detectors and satellites to explore particles and the universe, to nanostructured devices to probe the intrinsic properties of matter. For theory and modeling, powerful computing in addition to well documented library are essential resources.

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• the estimates can be assumed to be precise within a factor 3, with the assessment of minimal, maximal and average requirements; the numbers in the summary table do include a reasonable safety margin in order to not underestimate the requirements at the beginning of the lifetime of the data center.

It is worthwhile to note that the physical infrastructure of the data center has a much longer lifetime than the IT equipment the data center will host. Care has to be taken to design adaptable and scalable infrastructure. The planning, development and operations of this infrastructure is a significant endeavor and requires adequate human resources. Already the design of the infrastructure and its implementation either within the Center or at a dedicated location will require a very careful analysis. Only this detailed analysis will allow further detailing of the required resources for the development and operations of the IT infrastructure.

Centralized versus decentralized infrastructure

Historically, computing resources started by being centralized in large data centers. This organization reflected the fact that such resources were expensive and required maintenance by experts. Over time, as the costs of computer access came down and computer processing power increased, a different strategy was observed: a non-localized, less uniform, and more flexible organization of data centers. However, due to the explosion of the volume of data that is now produced by experimental devices, there is a need for a significant increase in processing and data storage capacity, far beyond the resources available through individual computers. Typically, large-scale clusters of multi-core processors that require appropriate infrastructure (electricity supply, space, heat evacuation, noise insulation) are a necessity for the pursuit of scientific research.

For a unique computing centerThe support of such an infrastructure requires adequate system engineering. It is less and less appropriate to ask Ph.D. students to manage such resources.

The concept of a centralized computing and data center for high-performing computer (HPC) resources, with at least one common HPC system engineer, has been recently recognized as the most favorable organization by a majority of the researchers who answered the recent HPC questionnaire launched at the University of Geneva.

Data center classificationThe Telecommunications Industry Association Standard for Data Centers (TIA-942)1 describes the requirements for data center infrastructure. The simplest is a Tier 1 data center2. This is basically a server room that follows basic guidelines for the installation of computer systems. The most stringent level is a Tier 4 data center, which is designed to host mission-critical computer systems, with fully redundant subsystems and compartmentalized security zones controlled by biometric access control methods. Another consideration is the placement of the data center in a subterranean context, for data security as well as environmental considerations, such as cooling requirements.3 According to this standard the group aims to meet Tier 2 or Tier 3 requirements for the vital part of the services that will be provided. For less critical services the design criteria of the data center will be relaxed.

ConnectivityCareful consideration will have to be given to the connectivity between the data center and its users internal to the University of Geneva on the one hand and between the data center and the outside world on the other. It is expected that the data transfer rate will scale with the total volume of the data available inside the data center.

1 - See http://www.adc.com/Attachment/1270711929361/102264AE.pdf2 - Note that in the context of CERN’s LHC experiments and their computing infrastructure Tiers are defined differently from TIA-942.3 - Source: Wikipedia

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2.Facilities

Machine and electronics workshops, and assembly hallsThe different groups gathered in the Center have an ongoing need to develop and build new instruments to carry out their research. These range from very large units of several cubic meters that can weigh several tons (ATLAS - A Toroidal LHC ApparatuS detector at CERN’s Large Hadron Collider and AMS - the Alpha Magnetic Spectrometer - on the International Space Station), to instruments that can be very complex but only a few centimeters or millimeters big and requiring great skills in precision engineering (scanning tunneling microscopes, pressure cells). To this end, the Center must have comprehensive and efficient machine and electronics workshops, as well as a locksmith. It will also provide sufficient space, sometimes under a controlled environment, to assemble and test the larger instruments.The specialties and strengths of the workshops will remain the same in the future as they are today, namely precision engineering, flexibility vis-à-vis the demands of researchers and excellence in prototyping and small series. The infrastructure of the workshops will serve all the research groups of the new Center. They will be complemented by a machine workshop with basic machine tools accessible to researchers themselves to carry out work as needed. A major constraint is the need for assembly halls that qualify for the treatment of sensors highly sensitive to mechanical, chemical and electrical pollution. This applies to both accelerator projects and space projects. Manufacturing areas, where the above pollutions are unavoidable, and the spaces destined for assembly work will be placed in close proximity for maximum efficiency, but will remain well separated to avoid contamination of the sensitive equipment.Another important aspect of the various workshops is consistency between the engineers who are part of the research groups and centralized technical services, along with the assembly rooms. Geographical proximity and even direct visual contact between the assembly halls and offices of the technical research groups


Adaptability and scalabilityAt present the bottleneck in computing infrastructure is in the available space, the cooling, and the electrical power of the installations. This adds to the need to provide users with a centralized facility in which they may install, in a coordinated way, machines that may be quite different. This centralized facility does not necessarily need to be co-located with the researchers using it, provided that the data transfer rates are adequate.The design of the future computing facility will require some careful study to ensure proper reliability and an architecture that meets the demands of the users rather than the wishes of the service providers. This point is all the more important since the needs of the users in the rapidly changing IT world environment will evolve significantly between the time when the facility is designed and when it will be used. Flexibility of the facility will also be a key feature, as the infrastructure that will be built in terms of surface, cooling and electrical power will have a much longer life than the computing and storage equipment that will be installed in the facility.

Thoughts on homogeneous or heterogeneous resourcesHaving centralized IT infrastructure does not mean that the equipment has to be uniform and all machines identical. One can imagine that, according to the specificity of the different research fields, different architectures will be deployed. Of course the maintenance of specialized equipment should then be the responsibility of the research groups using it. Such specific systems could be complemented by a more general purpose system, which is homogeneous and maintained directly by the common system engineer. Such a global machine will serve the groups that need standard resources or have irregular computing demands. Note also that, whether the different resources are homogeneous or not, their pooling is possible through virtualization and grid-like technologies (the combination of computer resources from multiple administrative domains to reach a common goal), resulting in a sharing of the unused CPU (central processing unit) cycles among the users.

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will be a major asset in the consistency of the chain running from production to assembly to verification.

Recent accomplishments in large dimension instrumentation for particle physics, astroparticles and astronomy include the production of silicon detector modules for ATLAS at CERN with their mechanical support, the scintillation hodoscope for the muon ionization cooling (MICE) experiment, the integration of the silicon tracking detector in the AMS space experiment, and the HARPS (High Accuracy Radial-velocity Planet Searcher) and HARPS-NORTH astronomy projects. These projects need infrastructure tailored to their construction, but more importantly, an infrastructure qualifying for assembly, integration and verification activities.

The ability to integrate instruments for large projects of the future into the heart of the Center will be one major asset for physics and astrophysics. The construction and assembly of large instruments are interesting both from a scientific point of view and in terms of visibility of the new Center. An important stream of visitors is predictable and assembly halls must have visitor galleries separated from the facilities by windows.

Cleanrooms

Cleanrooms in the new Center will cover a variety of needs, reflecting the diversity of research that will take place. These will range from gray rooms (class 100000) for the assembly of large structures (satellites, sensors for large accelerators) to cleanrooms including class-100 laminar flow environments for the production of advanced micro and nanostructures (integrated circuits, micro and nanostructures for electronics, and quantum optics).

The cutting-edge research in the new Center in the areas of space exploration and particles requires the capacity to develop, assemble and test new instruments that are often very bulky, delicate and complex. The area with cleanrooms capable of hosting satellites and instruments for space and detectors for large-scale terrestrial accelerators will provide a large, flexible area that can

be adapted to the size and vulnerability of instruments. These gray rooms will be equipped with a visitors’ gallery separated by glass on one side, and the offices of engineers and the technical groups on the other. This area will be near the machine and electronics workshops for optimum operational efficiency, while ensuring the separation of clean and polluting sides.

The development of nanoscale devices based on new materials requires cutting-edge facilities for their synthesis, such as thin film structure, their structuring on a nanometer scale, and their characterization. Most contemporary nanoscale devices use semiconductors (silicon, GaAs – gallium arsenide and other III-V semiconductor compounds), and conventional metals (copper, aluminum). Existing facilities capable of producing these nanostructures apply very strict rules about the use of different materials to avoid contamination that, when it comes to semiconductors, inevitably leads to the degradation of the performance of the devices. Thus existing infrastructures prevent, or at least greatly restrict, the development of nanostructures based on new materials.

Typical layout of a helium liquefaction site. (Credit: Air Liquide)

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and expensive commodity. Producing it on site is the most effective and economical way to meet such high demand. Moreover, it will benefit other laboratories of the Faculty of Science and the University with much more modest consumption.A cryogenic laboratory has several components, ranging from the production site to the user’s laboratory, and passing through recovery, purification and storage sites. All sites must be close to each other and connected by a pipe system for the recovery of helium in gaseous form after use.


The design and fabrication of innovative nanoelectronic devices in the new Center that exploit the characteristics of new materials require special facilities. To date, there is no one infrastructure that enables the combined synthesis of semiconductor components and new materials that are à priori not compatible. Such a facility, which still needs to be developed, will give a competitive advantage to the Faculty of Science and Geneva as a place of technological innovation. This flexibility implies that such a facility will be an asset not only for the making of new nanoelectronic devices, but guarantees the ability to adapt to forthcoming changes in materials and technologies. Among the key requirements of such a facility are the control of materials at the nanoscale through appropriate deposition methods, and advanced structuring techniques based on lithography, erosion and self-assembly. It is imperative to combine these synthesis skills with the necessary infrastructure to assess the electronic properties – starting materials as well as finished devices – on the same nanoscopic scales. To be competitive, the installation must be comprehensive and flexible, so as to limit the time between the synthesis of new devices and their characterization. Such a unit must bring together under one roof the necessary synthesis and characterization capabilities on a nanoscopic scale, a combination essential to maintaining control over all of these processes and the required technological expertise.

Cryogenic servicesSeveral research themes developed in the Center require access to very low temperatures, from liquid nitrogen (77K) up to a few microkelvins. Such temperatures are obtained with liquid helium. The consumption of liquid helium in the Physics section has increased exponentially since the introduction of the first liquefier in 1970, corresponding to the evolution of and increases in research activities. A maximum of 75,646 liters of liquid helium were produced in 2005 by the section, while consumption reached 72,693 liters in 2007.The research activities of the Center suggest that the consumption of liquid helium will remain at a high level. Liquid helium is a scarce

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PART IV . In the near future

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IV In the near future

Inauguration speech

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The Geneva Center for Astronomical, Physical and Mathematical Sciences

Welcome to a scientific achievement and architectural landmark in the history of Geneva and the astronomical, physical and mathematical sciences.

The new Center embodies a subtle balance between openness, a reassuring ease of use and needed privacy. The buildings immediately mirror the modular spirit of the project, ready to welcome and nurture the scientific initiatives that it will prompt.

The central hall is in itself a call to begin or resume studies. Working and interaction spaces are particularly well designed and easily accessible to all disciplines of the Center.

The campus spirit provided by the student housing completes efforts to create places that nourish the desire to learn at the heart of Geneva.

This is a place that favors the crossing of disciplines, while preserving the researcher’s necessary privacy. It is a site that incites people to stay, to think, and to study, to understand how others proceed to meet the challenges of research.

The attendance of all our visiting professors today, from Switzerland and abroad, emphasizes the success of the historical ties but also new collaborations initiated two years ago. The inter-faculty embassies have quickly found their marks with specific projects you have already appreciated.

The ScienScope has amazing educational and scientific communication abilities owing to its advanced visualization center and virtual reality studio. It will certainly break the reluctance of students and the general public alike to partake in the exploration of science. The holographic display is especially dazzling.

The Laboratory of Advanced Technologies is already an effective alliance between the University of Geneva and University of Applied Sciences. It is actively sought-after by local industries that seek to perpetuate or find a way back to basic research.

As the friends of the Center recalled this morning, in basic research it is less about finding the answer than to raise the right question. We must first imagine and then make what we imagined visible to others. Future researchers and prospective students must be helped to go beyond mechanization, to reach the thrill of discovery, while never forgetting that the main obstacle to scientific progress is the illusion of knowledge.

The convergence of all disciplines of the Center will always remind us of that, but its main aim is to activate the production of the energy of knowledge. This new energy will emerge from new observations, new research, new theories and new academic programs.

Let us hope this energy will bring us to new horizons, new dimensions, and help our new Center achieve its ambitions!

Inauguration speech

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Contributions

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Contributions

Professeur Øystein Fischer

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The two books – The Context and The Scientific Project – are part of a project initiated and led by professor Øystein Fischer to elaborate a proposal for the establishment of a Center of Astronomical, Physical and Mathematical Sciences, by mandate of the rector of the University of Geneva, professor Jean-Dominique Vassalli.

This book, The Scientific Project, is the result of a collective enterprise under the leadership of professors Øystein Fischer and Christoph Renner of the Faculty of Sciences of the University of Geneva with the supervision of the project Steering Committee.

Professors signatories of the project wrote the scientific texts.

Artistic Illustrations Frédéric Bilger, Etienne Francey, Ludovic Razin / Agence Etienne & Etienne (p 21, 35, 47, 58, 69, 79) François Robin (p 91, 98, 104, 112, 122, 128, 138)

Scientific Illustrations Selected by Christophe Berthod / MaNEP - UNIGE Olivier Gaumer / Physics section - UNIGE

Design, Graphics and Layout Etienne Francey / Agence Etienne & Etienne

Translation Danielle Carpenter Sprungli

Printing ABP Project printing solutions Sàrl

Coordination & Support Marie Bagnoud, Edward Coutureau / MaNEP - UNIGE Daria Lopez-Alegria, Julien Pitton / Science Bridges Sàrl

Steering Committee Anton Alekseev Marie Bagnoud Adriana Bonito Aleman Thierry Courvoisier Edward Coutureau Øystein Fischer Marie-Anne Gervais Thierry Giamarchi

Geneva, October 2011

Daria Lopez-Alegria Michele Maggiore Georges Meynet Alberto Morpurgo Patrycja Paruch Martin Pohl Julien Pitton Didier Raboud

Christoph Renner Stanislav Smirnov András Szenes Jean-Marc Triscone Stéphane Udry Dirk van der Marel Jean-Pierre Wolf

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Acronyms and abbreviations

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2-DeG 2-dimensional electron gasAFm atomic force microscopy AGN active galactic nuclei AIDA Advanced European Infrastructures for Detectors at AcceleratorsALmA Atacama Large Millimeter ArrayAmS Alpha Magnetic SpectrometerARPeS angle-resolved photoemission spectroscopy ASTRO-h X-ray astronomy satelliteATLAS A Toroidal LHC ApparatuS, a particle detector experiment at CERNCeRN Centre Européen pour la Recherche Nucléaire;

the European Organization for Nuclear ResearchCheOPS CH (Swiss) ExOPlanet Satellite CLIC Compact Linear Collider (CERN two-beam accelerator)CmB cosmic microwave backgroundCP charge conjugation symmetry (C) and parity symmetry (P)CPU central processing unitCTA Cerenkov Telescope ArrayCTI Swiss Commission for Technology and InnovationDeSY Deutsches Elektronen Synchrotron; German Electron Synchrotron,

the biggest German research center for particle physicsDIP Département de l’Instruction Publique;

Geneva Cantonal Department of EducationDPmC Département de Physique de la Matière Condensée;

Geneva’s Department of Condensed Matter PhysicsDPNC Department of Nuclear and Particle Physicse-eLT European Extremely Large Telescope eSA European Space AgencyeSO European Southern ObservatoryeSPReSSO Echelle SPectrograph for Rocky Exoplanets

and Stable Spectroscopic ObservationseSRF European Synchrotron Radiation FacilityeUCLID A European Space Agency satellite with the primary goal

of mapping the geometry of the dark universeeUDeT Detector R&D towards the International Linear ColliderFT-STm Fourier Transform scanning tunneling microscopyGAP Group of Applied Physics of the University of GenevahARPS High Accuracy Radial-velocity Planet SearcherheS Haute Ecole Spécialisée de Suisse Occidentale;

University of Applied Sciences Western SwitzerlandhPC high-performing computerhST Hubble Space TelescopeIhP Institut Henri Poincaré, FranceINRIA Institute National de Recherche en Informatique

et en Automatique; the French national institute for Research in Computer Science and Control

INTeGRAL International Gamma-Ray Astrophysics LaboratoryIPCC Intergovernmental Panel on Climate ChangeITeR International Thermonuclear Experimental ReactorIR infraredISDC Data Centre for Astrophysics

ISe Institute des Sciences de l’Environnement; Institute of Environmental Sciences

IUFe Institute Universitaire pour la Formation des Enseignants; University Institute for Teacher Training

IXO International X-ray ObservatoryJem-eUSO Japanese Experiment Module-Extreme Universe Space ObservatoryJWST James Webb Space TelescopeK2K KEK to Kamioka, a neutrino experiment much like T2K (see below)KITP Kavli Institute for Theoretical PhysicsLDA local density approximationLDA+DmFT local density approximation + dynamical mean-field theoryLeeD low-energy electron diffraction LeP Large Electron Positron experiments at CERNLhC large hadron colliderLIGO Laser Interferometer Gravitational-Wave ObservatoryLISA Laser Interferometry Space AntennamaNeP Materials with Novel Electronic Properties mICe muon ionization cooling experimentNASA National Aeronautics and Space AdministrationNCAR National Center for Atmospheric ResearchNCCR mUST National Center of Competence in Research Molecular Ultrafast

Science and TechnologyNGTS Next Generation Transit SurveysNSOm near field scanning optical microscopy ODe ordinary differential equationsPDe partial differential equationsPeTRA Positron-Electron Tandem Ring AcceleratorPLATO PLAnetary Transits and Oscillations of starsPLL Physics Learning LaboratoryPOLAR A compact detector for Gamma Ray Burstsphoton

polarization measurementsPRImA Phase-Referenced Imaging and Microarcsecond Astrometry QPI quasiparticle interference patternsRAL Rutherford Appleton Laboratory ShRImP second harmonic radiation imaging probeSNSF Swiss National Science FoundationSPheRe Spectro-Polarimetric High-contrast Exoplanet REsearch SPICA Space Infrared Telescope for Cosmology & AstrophysicsSQUIDs superconducting quantum interference devicesSp S A proton-antiproton colliderSTm scanning tunneling microscopySWASP Super Wide Angle Search for Planets,

the UK’s leading extra-solar planet detection programT2K Tokai to Kamioka, Japanan experiment sending an intense off-

axis beam of muon neutrinos from Tokai to Kamioka, Japan.TeV teraelectron voltVIRGO Variability of solar Irradiance and Gravity OscillationsVLT Very Large Telescope (European)WmO World Meteorological Organization

Acronyms and abbreviations

Livre science anglais

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