Atomtronics

AtomtronicsAn Ultra cold Analogue of Semiconductor Devices and Circuits

Submitted bySushant RawatECERoll no- 07820902811

Introduction and Theory

Atomtronics is a branch of Science , Engineering and Technology that deals with the creation of analogues of electronic circuits and devices by the use of Atoms.

Atomtronics is an emerging technology that offers a wide range of applications.

In Atomtronics , the current carriers in electronics is replaced with Ultracold atoms.

The Ultracold atoms have interesting properties that conventional materials lack Superfluidity, SuperConductivity and Coherence.Atomtronics is a young and mostly theoretical field based on the idea that atoms in unusual quantumstates of mattermay provide an alternative to the tried-and-true electron for making useful devices.

The idea is to manipulate neutral atoms using lasers in a way that mimics the behaviour of electrons in wires, transistors and logic gates.SuperconductivitySuperconductivity is the ability of certain materials to conduct electric current with practically zero resistance.

This produces interesting and potentially useful effects. For a material to behave as a superconductor, low temperatures are required.

In atomtronics the atoms are ultra cold and thus exhibit the superconductivity property.SuperfluidityIt is a state of matter in which the matter behaves like a fluid with zero viscosity ; where it appears to exhibit the ability to self-propel and travel in a way that defies gravity and surface tension.

The phenomenon is related to the Bose-Einstein condensation.

The ultracold atoms exhibit this property.CoherenceCoherence is attained when there is a constant phase difference in two or more waves over time.

Two types of coherence:Spatial CoherenceTemporal Coherence

The atomtronics provides the coherence.

The science behind AtomtronicsPhysicists Satyendra Nath Bose and Albert Einstein proposed in 1924 that large number of atoms could be chilled to the point that they joined together in a single quantum state, bringing subatomic effects to a scale accessible by laboratory experiments.

In 1995 scientists made a Bose-Einstein condensate (ultra cold gas) using lasers to carefully cool rubidium-87 atoms.

The first pure Bose-Einstein condensate was created by Eric Cornell and Carl Wiemann.

Eric Cornell and Carl WeimanWhat is the Bose Einstein Condensation In the early 1920sSatyendra Nath Bosewas studying the new idea (at that time) that the light came in little discrete packets (we now call these "quanta" or "photons"). Bose assumed certain rules for deciding when two photons should be counted up as either identical or different. We now call these rules "Bose statistics" (or sometimes "Bose-Einstein statistics").Einstein guessed that these same rules might apply to atoms. He worked out the theory for how atoms would behave in a gas if these new rules applied.What Einstein's equations predicted was that at normal temperatures the atoms would be in many different levels. However, at very low temperatures, a large fraction of the atoms would suddenly go crashing down into the very lowest energy level and most of the atoms will be in the same quantum level.How was the Bose-Einstein Condensation made ? Eric Cornell and Carl Wieman in 1995, made Bose-Einstein condensate by cooling atoms to a much lower temperature than had been previously achieved.

Their technique used laser light to first cool and hold the atoms, and then these atoms were further cooled by called evaporative cooling.

The success of the Bose-Einstein condensation experiment, opened the gates to the possibility of the development of Atomtronics technology.

The Need for AtomtronicsAtomtronics provides Superconductivity and Superfluidity.

The experimental atomtronics realizations promise to be extremely clean. Imperfections such as lattice defects or photons can be completely eliminated.

Atomtronics allows study of an idealised system.

Atomtronics systems are richer than their electronic counterparts because atoms possess more internal degrees of freedom than electrons and interaction between these can be widely varied from strong to weak.

Atomtronics in Quantum ComputerAquantum computeris a device forcomputationthat makes direct use ofquantum mechanicalphenomena, such assuperpositionandentanglement, to perform operations ondata. Quantum computers are different from digital computers based ontransistors. Whereas digital computers require data to be encoded into binary digits (bits) , But In quantum computing we store a quantum state on an object, perform operations on the object and then read out the final state.Atoms trapped in optical lattices (in Atomtronics devices ) have been considered extensively useful for specific quantum computing schemes due to their inherent energy conserving characteristics. Therefore the dynamics of atomtronic devices would be coherent and potentially useful in quantum computing.Atomtronics DevicesIt has been concluded that atomtronic systems provide a nice test of fundamental concepts in condensed matter physics. While these ideas have been modelled, they are yet to be built. They are :-

Atomtronic ConductorAtomtronic diodeAtomtronic TransistorAtomtronics ConductorAn attractive feature of atomtronic materials is that their conductivity properties can be easily modified.

The primary conductor for an atomtronic system is an optical lattice with no other external potentials. This corresponds to a wire in an electronic system.

And current refers to the number of atoms that pass a specific point in a given amount of time.

Atomtronic DiodeThe atomtronic analogy of a diode formed from the joining of p-type and n-type semiconductor materials.

Electrons are replaced by ultracold atoms.

Battery is replaced by high and low chemical potential reservoirs.

Atomtronic TransistorThe desired function of an atomtronic transistor is to enable a weak atomtronic current to be amplified or to switch, either on or off, a much larger one and acts as an amplifier. Transistor action requires at least three lattice sites connected to three independent reservoirs. The resonance condition for this device is found to be an extension of the diode case to account for the third well: the left external energy is shifted above the middle site by the on-site interaction energy and is of equal energy to that of the right site.By configuring the optical lattice in a manner researchers show that it is possible to recover the characteristics of the conventional electronic transistor in the atomic world.Reference

http://jila.colorado.edu/content/quantum-dynamics-condensates-atomtronic-systems-and-photon-fluidshttp://nextbigfuture.com/2009/10/atomtronic-circuits-of-diodes-and.htmlhttp://www.geeky-gadgets.com/why-is-atomtronics-important-13-02-2011/http://cdsweb.cern.ch/record/966590http://martyscoolstuff.blogspot.com/2011/02/why-is-atomtronics-important.htmlhttp://www.opticsinfobase.org/abstract.cfm?uri=LS-2006-LMG2http://www.physorg.com/news174303837.html

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