Download presentation
Presentation is loading. Please wait.
1
Superfluidity of Polaritons in Engineered Potentials in Semiconductor Microcavities
Alberto Amo, C. Adrados, J. Lefrère, E. Giacobino, A. Bramati Laboratoire Kastler Brossel, UPMC, ENS, CNRS, Paris, FR S. Pigeon, C. Ciuti Laboratoire MPQ, Université Denis Diderot, CNRS, Paris, FR I. Carusotto BEC-CNR-INFM and Dipartimento di Fisica, Universita di Trento, Povo, IT R. Houdré Institut de Physique de la Matière Condensée, EPFL, Lausanne CH
2
Outline Polaritons in semiconductor microcavities
Observation of superfluidity of polaritons Engineering the polariton landscape
3
Semiconductor microcavities
Angle θ (º) θ GaAs Upper polariton kin-plane Photon Emission energy (eV) Exciton ~ 5meV Top DBR Quantum Wells Lower polariton Bottom DBR kin-plane (μm-1) Polaritons The partial photonic character renders a very low mass The partial excitonic character provides the system with strong non-linearities
4
Semiconductor microcavities
Angle θ (º) θ GaAs Upper polariton kin-plane Photon Emission energy (eV) Exciton ~ 5meV Top DBR Quantum Wells Lower polariton Bottom DBR kin-plane (μm-1) Polaritons The partial photonic character renders a very low mass The partial excitonic character provides the system with strong non-linearities Properties Composite bosons Excitonic component strong interactions (non-linearities 3) Photonic component low mass (10-5 me) Short lifetime (~ps) out of equilibrium
5
Polariton condensation
Excitation m/me Tc lT at Tc Atomic BEC 104 <1 mK 1 mm Polariton condensate 10-5 K 1-10 mm Emission energy (eV) Lower polariton kin-plane (μm-1) Polariton density T = 5 K CdTe ky kx Kasprzak et al. Nature, 443, 409 (2006)
6
Polariton quantum fluid effects
Quantized vortices (m=1) Interferogram Phase map Lagoudakis et al., Nature Phys. 4, 706 (2008) Imprinted vortices (m=1,2) and persistent currents Sanvitto et al., Nature Phys. DOI: /NPHYS1668 (2010)
7
Polariton quantum fluid effects
Quantized vortices (m=1) Fluid dynamics Interferogram Phase map Real space Lagoudakis et al., Nature Phys. 4, 706 (2008) Momentum space Imprinted vortices (m=1,2) and persistent currents Amo et al., Nature 457, 291 (2009) Sanvitto et al., Nature Phys. DOI: /NPHYS1668 (2010)
8
Landau criteriom for superfluidity
Interacting Boson condensate linearized spectrum of excitations E cs k
9
Landau criteriom for superfluidity
Interacting Boson condensate linearized spectrum of excitations SUPERFLUID E E Galilean boost cs+vf cs FLOW cs-vf vf < cs k k
10
Landau criteriom for superfluidity
Interacting Boson condensate linearized spectrum of excitations SUPERFLUID E E Galilean boost cs+vf cs FLOW cs-vf vf < cs k k ČERENKOV REGIME E E Galilean boost cs+vf cs cs-vf FLOW vf > cs k k I. Carusotto and C. Ciuti, phys. stat. sol. (b) 242, 2224 (2005)
11
Polariton superfluidity
Resonantly excited condensate with low momentum Elastic scattering E - Ep Pump ky (mm-1) Linear regime Real space FLOW 30 µm Momentum space Polariton density
12
Polariton superfluidity
Resonantly excited condensate with low momentum Elastic scattering Collapse of the ring E - Ep E - Ep Pump vf < cs Pump ky (mm-1) ky (mm-1) Linear regime Superfluid 1 Real space FLOW 30 µm Momentum space Polariton density Amo et al., Nature Phys. 5, 805 (2009)
13
Polariton superfluidity Gross-Pitaevskii simulations
Resonantly excited condensate with low momentum Elastic scattering Collapse of the ring E - Ep E - Ep Pump vf < cs Pump ky (mm-1) ky (mm-1) Linear regime Superfluid 1 Real space FLOW 30 µm Gross-Pitaevskii simulations FLOW 30 µm Polariton density Amo et al., Nature Phys. 5, 805 (2009)
14
Superfluid regime
15
Čerenkov regime (supersonic) Gross-Pitaevskii simulations
High momentum Elastic scattering Linear wavefronts vf > cs E - Ep E - Ep Pump supersonic ky (mm-1) ky (mm-1) Linear regime Čerenkov 1 Real space FLOW 40 µm Gross-Pitaevskii simulations FLOW 40 µm Polariton density Amo et al., Nature Phys. 5, 805 (2009)
16
Čerenkov regime (supersonic) Gross-Pitaevskii simulations
High momentum Elastic scattering Linear wavefronts vf > cs E - Ep E - Ep Pump supersonic ky (mm-1) ky (mm-1) Linear regime Čerenkov 1 Supersonic atomic BEC Carusotto et al. PRL 97, (2006) Real space q FLOW 40 µm Gross-Pitaevskii simulations FLOW 40 µm Polariton density Amo et al., Nature Phys. 5, 805 (2009)
17
Polariton landscape engineering
probe σ + FLOW 20 μm Defect-free area h_bar k = mv
18
Polariton landscape engineering
polariton-polariton interaction probe σ + control σ - + FLOW 20 μm 20 μm Defect-free area Strong field: renormalization of the polariton energy h_bar k = mv control Polariton energy y
19
Polariton landscape engineering
polariton-polariton interaction probe σ + control σ - probe σ + + control σ - detection σ + + = FLOW FLOW 20 μm 20 μm Defect-free area Strong field: renormalization of the polariton energy h_bar k = mv control Polariton energy y Amo et al., arXiv: v1
20
Polariton landscape engineering
Probe + Probe + Probe only horizontal control diagonal control No control injected injected scattered injected 30 μm scattered h_bar k = mv Amo et al., arXiv: v1
21
Polariton landscape engineering
Probe + Probe + Probe only horizontal control diagonal control No control injected injected scattered injected 30 μm scattered h_bar k = mv Amo et al., arXiv: v1
22
Polariton landscape engineering SUPERFLUID REGIME (high probe power)
Probe only horizontal control diagonal control No control injected injected scattered injected injected 30 μm scattered no scattering h_bar k = mv Amo et al., arXiv: v1
23
Josephson oscillations
Summary Observation of superfluidity of polaritons Supersonic regime access to the sound speed h_bar k = mv Polariton-polariton interactions landscape engineering localization effects polariton circuits Josephson oscillations
24
Single polariton fluid: set-up
X Y Near field CCD Far field CCD q k kz k║ Microcavity sample Excitation laser Single laser excitation (CW, single mode) resonant excitation of one polariton mode Excitation close to the bottom of the lower polariton branch UPB LPB Transmission experiment CW Pump
26
SUPERFLUID AROUND SEVERAL DEFECTS SHADOW EFFECT AROUND BIG DEFECT
Other situations SUPERFLUID AROUND SEVERAL DEFECTS FLOW 40 µm SHADOW EFFECT AROUND BIG DEFECT h_bar k = mv FLOW 40 µm Polariton density
27
Superfluidity checklist
Nature 457, 273 (2009) h_bar k = mv Resonantly pumped polariton condensates Amo, Lefrère, et al., Nature Physics, (in press). I Carusotto talk at ICSCE 4 conference (Cambridge, UK, 2008), available at
28
Polariton fluid dynamics: set up
sample Lens F X Y Fourier plane 2ps pulsed fA Microcavity sample (grown at LPN) IDLER CW Lens A real space imaging PUMP Energy selection imaging spectrometer Lens B momentum space imaging l/2 cavity 20 nm GaAs QW Streak Camera CCD ħΩRabi = 4.4 meV ky kx
29
Polariton landscape engineering
polariton-polariton interaction probe σ + control σ - probe σ + + control σ - detection σ + + = FLOW FLOW 20 μm 20 μm Defect-free area Strong field: renormalization of the polariton energy Simulation GP h_bar k = mv control FLOW Polariton energy y Amo et al., arXiv: v1
30
Polariton landscape engineering
polariton-polariton interaction probe σ + control σ - probe σ + + control σ - detection σ + + = FLOW FLOW 20 μm 20 μm Defect-free area Strong field: renormalization of the polariton energy h_bar k = mv Real defect control FLOW Polariton energy 30 µm y Amo et al., arXiv: v1
31
Polariton fluid dynamics
Original streak camera set-up Study of the dynamics of polariton wavepackets v = 1.2 mm/ps (~1% light speed) t = 7 ps t = 28 ps t = 48 ps 20 μm Division in two in the presence of a big defect t = 8 ps t = 25 ps t = 45 ps 20 μm Amo et al., Nature 457, 291 (2009)
32
TOPO Coexistence of three fluids Steady state CW (pump) 100 mm spot
Triggered OPO (signal) 16 mm spot fed by pump Idler Pulse CW Pump TOPO Signal TOPO Idler LPB UPB Pump polaritons Energy Signal polaritons Amo et al., Nature 457, 291 (2009)
33
Linear dispersion 1 DE Amo et al., Nature 457, 291 (2009)
pol-pol interaction normal mode coupling decay CW Pump Pulsed probe 1 DE Amo et al., Nature 457, 291 (2009)
34
Coherent propagation t= 7ps t= 28ps t= 48ps a b
Amo et al., Nature 457, 291 (2009)
35
Flow through a defect Amo et al., Nature 457, 291 (2009) I t= 8ps
b 2.5 0.0 Amo et al., Nature 457, 291 (2009)
36
compatible with superfluid behaviour
Frictionless flow E=ħpump Pump polaritons Pump fluid: scattering waves Signal fluid no scattering with the defect Peaked momentum E=ħsignal Signal polaritons compatible with superfluid behaviour kX kY K-space real space Amo et al., Nature 457, 291 (2009)
37
Noise studies in the superfluid regime
Intensity noise polariton density statistics Noise decreases in the superfluid regime Superfluid threshold h_bar k = mv
38
Splitting in two II t = 8 ps t = 25 ps t = 45 ps a b
Amo et al., Nature 457, 291 (2009)
39
Polariton superfluidity High density (quantum fluid regime)
T = 5 K High density (quantum fluid regime) Low density Linear regime Superfluid Čerenkov vf<cs vf >cs 30 µm FLOW 30 µm FLOW 40 µm FLOW Scattering with defects Fluid without friction Linear wavefronts Amo et al., Nature Physics 5, 805 (2009)
40
Polariton superfluidity High density (quantum fluid regime)
Low density T = 5 K Linear regime Superfluid Čerenkov vf<cs vf >cs 30 µm FLOW 30 µm FLOW 40 µm FLOW Scattering with defects Fluid without friction Linear wavefronts Amo et al., Nature Physics 5, 805 (2009)
41
Čerenkov regime (supersonic) Gross-Pitaevskii simulations
High momentum Elastic scattering Linear wavefronts vf > cs E - Ep E - Ep Pump supersonic ky (mm-1) ky (mm-1) Linear regime Čerenkov 1 Real space FLOW 40 µm Gross-Pitaevskii simulations FLOW 40 µm Polariton density Amo et al., Nature Phys. 5, 805 (2009)
Similar presentations
