Quantum coherence in semiconductor nanostructures

Jacqueline Bloch

Laboratoire of Photonic and Nanostructures

LPN/CNRS

Marcoussis

Jacqueline.bloch@lpn.cnrs.fr

Laboratoire de Photonique et de Nanostructures

Marcoussis

A CNRS Laboratory 30 km south of Paris

Growth facilities

Processing facilities

Physical studies

50 permanent researchers

www.lpn.cnrs.fr

What are semiconductor nanostructures ?

e-

Confine electrons in a volume with dimensions comparable to the De Broglie wavelength (typically 1 nm)

Quantum confinement : quantization of the energy levels

Lx

k = pΠ/L

Quantum Wells

1

Growth direction

2 2

2D Continuum

Emission

Inter-band transition

Intra-band transition

What are semiconductor nanostructures ?

e-

Confine electrons in a volume with dimensions comparable to the De Broglie wavelength (typically 1 nm)

Lx

Quantum Dots : 3D confinement

Discrete quantum states

« artificial atom » in a solid state system

~

Energie (meV)

1340 1345 1350 1355

xγ 1-10 µeV

Em

issi

on

in

ten

sity

Quantum confinement : quantization of the energy levels k = pΠ/L

TEM G. Patriarche

Optics in microcavities

Confine light in small volumes (of the order of λ3)

Modify the light matter coupling

Miroir interférentiel

Miroir interférentiel

micropillars

AlAs

GaAs/AlGaAs

n=1

microdisks Photonic crystal microcavities

Interferential mirrors

Interferential mirrors

Quantum coherence in semiconductor nanostructures

Control of these quantum emitters, enhance light matter interaction,

manipulate single spins

- Bose condensates; new optical functionalities

- Non-linear optics at the single photon level

- Cavity quantum electrodynamics

- Quantum information processing

- Source of quantum light : quantum cryptography, teleportation

Upper polariton

Lower polariton

~ 5meV

-2 0 2

-20 -10 0 10 20

Top DBR

Bottom DBR

Quantum Wells

θGaAs/AlGaAs based structures

Exciton

Photon

Angle θ (º)

kin-plane (µm-1)

Em

issi

on e

nerg

y (e

V)

Microcavity polaritons : mixed exciton-photon states

5 K

Semiconductor cavities : a model system to investigate

the physics of Bose condensates

Bosonic quasi-particule (J = +-1)

Low effective mass => Large De Broglie wave length

=> Condensation at high temperature

12 22

TBmk T

πλ

=

h

Bose-Einstein condensation

Cornell’s and Wieman’s groups:

condensation of Rb atoms (1995)T

http://jilawww.colorado.edu/bec/

12 22

TBmk T

πλ

=

h

Macroscopic wavefunctionBEC with atoms

Nature 443, 409 (2006)

Kasprzak et al. Nature, 443, 409 (2006)kx

ky

Polariton density

T = 5 K CdTe

Low critical temperatures: < 1 µK

Typical experimental scheme

(d)Far field

Flo

w

30 µm

Interference with a reference beam

Coherence mapg(1)

0

1

Density

Phase dislocations- vortices- solitons

-0.5 0.0 0.5

kx (µm-1)k y

(µm

-1)

kx (µm-1)

Ene

rgy

Far field imaging: k space Near field imaging: real space

Resonant injection ofpolaritons

THEORY GROUP at Laboratoire MPQ, Université Paris Diderot

Responsable: Prof. Cristiano CIUTI

Web page: http://www.mpq.univ-paris7.fr/

Google search: Laboratoire MPQ THEORIE

Main theoretical activity (semiconductors):

- Polariton quantum fluids (photons)

- Ultra- strong coupling in cavity quantum

electrodynamics cavité (circuit)

Recent review:

I. Carusotto & C. Ciuti, Reviews

of Modern Physics in press;

http://arxiv.org/abs/1205.6500

Alberto Bramati

Cavity polaritons:

coherence and spin dynamics

Quantum fluid : superfluidity, solitons,..

Nature Physics 2009

Science 2011

Science 2012

Spin switch, spin Hall effect

Nature Physics 2009

Vortex lattices

Laboratoire of Photonique and Nanostructures

http://www.lpn.cnrs.fr/fr/GOSS/CFMC.phpAlberto Amo

Jacqueline Bloch

Manipulating Bose condensate in photonic circuits

Macroscopic propagation and coherence

Trapping

Ferrier et al.

PRL 106, 126401 (2011)

Wertz et al., Nature Physics 6, 860 (2010)

Tanese et al. PRL 108, 36405 (2012)

Wertz et al., PRL to appear

Galbiati et al.

PRL 108, 126403 (2012)

λ/2 cavity

30 pairs

3x4 GaAsquantum wells

Substrate

26 pairs

λ/2 cavity

30 pairs

3x4 GaAsquantum wells

Substrate

26 pairs

GaAs/GaAlAs

microcavities

I. Shelykh et al., PRL 102, 046407 (2009)

Bloch oscillations: H. Flayac et al., Phys. Rev. B 84, 125314 (2011)

Phys. Rev. B 83, 045412 (2011)

Propagation, interaction of gap solitons

Polariton interferometerCondensation in a periodic potential:

Arrays of coupled condensates

Bose Hubbard quantum phases

What is next?

Carusotto et al., PRL 103 033601 (2009)

Fisher et al., PRB 40, 546-570 (1989)

http://www.lpn.cnrs.fr/fr/GOSS/CFMC.php

Laboratoire of Photonique and Nanostructures

Manipulating Bose condensate in photonic circuits

MPQ – Université Paris DiderotQuantum Physics and Devices (QUAD)

A. Vasanelli, M. Amanti, S. Barbieri, Y. Todorov, C. Sirtori

Building blocks:

Electron confinement:

Semiconductor QWs,

band structure engineering

Photon confinement:

plasmonic microcavities,

highly subwavelength

confinement

Fields of action

We develop novel concepts of quantum engineering

in materials that are currently at the basis of ICT.

THz quantum cascade laser Electroluminescence from

intersubband polaritons

L. Sapienza et al., PRL 2008

Y. Todorov et al., PRL 2009

Y. Todorov et al., PRL. 2010

S. Barbieri et al. Nature Phot. 2011

S. Barbieri et al. Nature Phot. 2010

Integrated quantum

cascade laser modulator

J. Teissier et al. Opex 2012

Group: Optical properties of hybrid nanostructures

Emmanuelle Deleporte (Pr) Jean-Sébastien Lauret (MdC)

LPQM

ENS Cachan

Strong coupling regime at

room temperature

Self-organized hybrid quantum wells:

Perovskites

(R-NH3)2MX4

M: Pb; X: I, Br, Cl

R: Phényl, Cyclohexane.…

3.2 3.3 3.4 3.5 3.6 3.7 3.8

50°

45°

40°

35°

30°25°

20°15°10°5°

Pho

tolu

min

esce

nce

Energie (eV) 2,0 2,2 2,4 2,6 2,8 3,0 3,2 3,4 3,6 3,8 4,0

m = 3

m = 2

m = 1m = 3

m = 2

m = 1

2,40 eV 3,07 eV

PhE-PbBr4

3,65 eV

Den

sité

opt

ique

Energie (eV)

PhE-PbCl4

PhE-PbI4

Tunability

Publications:

Superlattices and Microstructures 47, 10 (2010)

Appl. Phys. Lett. 93, 081101 (2008);

New Journal of Physics 10, 065007 (2008)

New Journal of Physics 10, 065017 (2008)

Appl. Phys. Lett. 90, 091107 (2007)

Phys. Rev. B 74, 235212 (2006)

Appl. Phys. Lett. 89, 171110 (2006)

a)

Objectives : Study of this new material (electronic properties)

Polariton condensation

Electrical injection

Quantum physics with single quantum dots

- Single spin in a quantum dot : a quantum bit

- Source of quantum light

- Cavity quantum electrodynamics using single quantum dot in a cavity

A spin in a Quantum dots : a quantum bit ?

electron

TEM G. Patriarche

A single spin : a well « isolated » quantum bit ?

�Spin optical pumping :

Science 312, 551 (2006), Phys. Rev. Lett. 99, 097401 (2007);Nature 451 441 (2008)…

� Quantum non demolition spin measurement: Science 314. 1916 (2006) , Nature Physics 3, 101 (2007)…

� Spin coherence: interaction with nuclei Phys. Rev. Lett. 94, 116601 (2005), Phys. Rev. Lett. 102, 146601 (2009)

Nature Physics, 5(8) 2009, Arxiv arXiv:1202.4637, …

T=4 K

TEM G. Patriarche

Quantum dots : a solids tate source of quantum light

1345 1350 1355Lum

ines

cenc

e in

tens

ity (

a. u

.)

Energy (meV)

X

XX

Single photon emission Science 290, 2282 (2000)

Semiconductor quantum dots

for the generation of non classical states of light

• Resonant Rabi oscillations: qubit initialization

0 12 24 36 48 600

2000

4000

6000

P1/2 (µW1/2)

Lum

ines

cenc

e (a

rb. u

nits

)

0000 5π5π5π5π4π4π4π4π3π3π3π3π2π2π2π2π

ππππ

cos=ψ 0 1+

2

θsin

2

θ

• Coherent control of the qubit:

0

1

δ, φ

903 904 905 906 907

φ = 0 φ = π

µP

L In

tens

ity (

arb.

uni

ts)

Wavelength (nm)

θ =π/2

« on »

« off »

θ: Rabi frequency Pulse area∝ P

•Purpose: Efficient indistinguishable

single photon source

• Entanglement of qubits

Applications in quantum information

• Indistinguishable single photon sources ?

increase of T2/T1

-24,4 -12,2 0,0 12,2 24,4 36,60

10

20

30

Coi

ncid

ence

s

Retard (ns)

HBT on-resonance

g (2) (0) = 0.06

(Collaboration: LPA, LPN)

HBT on resonance

Valia Voliotis,

Richard Hostein

300 < T2 < 600 ps (< 2 T1 )600 < T1 < 900 ps

http://www.insp.jussieu.fr/

Quantum optics in single quantum dots

-6 -4 -2 0 2 4 60.0

0.2

0.4

0.6

0.8

1.0

1.2

g(2)(τ

)

τ (ns)

Optically-gated resonant emission in single quantum dotsH. S. Nguyen et al., Phys. Rev. Lett. 108, 057401 (2012)

Ultra-coherent single photon sourceH. S. Nguyen et al., App. Phys. Lett. 99, 261904 (2011)

-10 -5 0 5 100

10

20

30

40

50

60

70Gate ONGate OFF

Inte

nsity

(10

3 co

unts

/s)

δ (µeV)

Resonant laser

Optical

gate

Optically-gated

resonant emission

0.0

0.1

0.2

0.3

0.4

0.0 0.5 1.0 0.0 0.5 1.0 0.0 0.5 1.0

-10 0 100.0

0.5

1.0

1.5

-10 0 10 -10 0 10

g(1)(τ

)

τ (ns)

τ (ns)

τ (ns)

E - EL (µeV) E - E

L (µeV)E - E

L (µeV)

Nor

m. i

nten

sity

Carole Diederichs

Laboratoire Pierre Aigrain

A quantum dot in a cavity :

A solid state system for quantum information processing

Contact : Pascale Senellart and Loic Lanco

Laboratoire de Photonique et de NanostructuresMarcoussis, France

QD

cavity mode

Optical loss

g

τc

e-

Artificial atom

Single photons source

Single spin memoryMicrocavities

Controlling spontaneous emission

Mixed light-matter states

http://www.lpn.cnrs.fr/fr/GOSS/BQM.php

Full control of a single dot spontaneous emission

See Dousse et al, Phys. Rev. Lett 2008, APL 2009

Suffczynskii et al, PRL 2009

Dousse et al, PRL 2008

Dousse et al, APL 2009

In-situ lithography

0.0 0.2 0.4 0.6 0.8 1.0 1.2

100

1000

10000

PL

inte

nsity

(a.

u.)

time (ns)

ON resonance (5 K)

OFF resonance (50K)

= 1.15 nsτXX

= 130 psτ

XX

0.0 0.2 0.4 0.6 0.8 1.0 1.2

100

1000

10000

PL

inte

nsity

(a.

u.)

time (ns)0.0 0.2 0.4 0.6 0.8 1.0 1.2

100

1000

10000

PL

inte

nsity

(a.

u.)

time (ns)

ON resonance (5 K)

OFF resonance (50K)

= 1.15 nsτXX = 1.15 nsτXXτXX

= 130 psτ

XX = 130 psτ

XXτ

XX

On demand Purcell effect

Light matter entangled

states

Ultrabright sources for quantum information processing

Single photons, Indistinguishable photons

Entangled photon pairs

Pulsed excitation

Few photon optical non-linearity

Dousse et al, Nature 2010, Gazzano et al, 2012

Loo et al, PRL 2012

104

Incident photons per pulse

Re

fle

ctiv

ity

0.88

0.86

0.84

0.82

0.80

0.7810-1 101100 102 103

0.90

8 photons

Toward a solid state quantum network ?Teleportation, Spin photon entanglement, entanglement

distillation, remote spin entanglement, delayed photon

entangler

V

�Single photon source�Entangled photon pair source

�Delayed photon entangler

�Spin based quantum memory�Single photon

optical switch

Optional course: second semestre

Laboratoire Photonique et Nanostructures

LPN/CNRS

Marcoussis (http://www.lpn.cnrs.fr)

Laboratoire Matériaux et Phénomènes Quantiques

MPQ/ Université Paris 7

http://www.mpq.univ-paris7.fr/

Pascale Senellart Jacqueline Bloch Cristiano Ciuti Carlo Sirtori