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Vortices and superfluidity in exciton-polariton condensates
Published on Apr 04, 20144320 Views
Polaritons are amazing quasiparticles originating from the coupling of photons with excitons (electron‐hole pairs in semiconductors). Polariton condensates may be created both spontaneously through a
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Rolex learning center @EPFL, by Saan!1a00:00
Vortices and superfluidity in polariton condensates02:23
Agenda03:08
Bose-Einstein condensation03:36
S.N. Bose 1924: concept of light quanta as particles with 2 polarization states03:57
Albert Einstein, 192504:36
Superfluidity05:05
It took 70 years to observe what Bose & Einstein foresaw05:47
Bose-Einstein condensates of rubidium atoms06:22
Observation of vortex lattices in Bose-Einstein condensates07:27
Origin of the idea of polaritons?07:59
Monolythic BDR microcavity09:08
Vertical Cavity Surface Emitting Laser: VCSEL10:48
Claude Weisbuch and Atac Imamoglu11:38
Semiconductor microcavities12:47
Microcavity polaritons: Half light / half matter particles15:23
Our Grenoble friends16:30
Direct access to the polariton both in k-space & real space17:02
Excitation laser17:58
Polariton Condensation18:24
The experiment18:55
Measurement of spatial coherence19:27
Measurement of spatial coherence: Principle20:56
Condensation of polaritons: Apparition of long range order21:51
Polariton condensation overview22:34
Vortices in Polariton quantum fluids23:20
Observation of vortices from interferogram24:35
The equations25:39
Kibble-Zurek mechanism26:45
Half vortices in spinor quantum fluids28:46
Simultaneous measurement in σ+ and σ−29:57
Full vortices in circular polarization30:18
Half vortices in circular polarization30:34
Now the phase trough Fourrier transformation31:18
σ+ - σ− coherence through Polarization mixing31:19
Half vortex with polarisation mixing interference31:37
How to probe superfluidity?31:48
Superfluidity and critical velocities in nonequilibrium Bose-Einstein condensates33:15
Superfluidity of polaritons in semiconductor microcavities34:33
Theoretical background35:15
Hydrodynamics of polariton fluids36:04
Dark solitons in polariton fluids36:46
How do we probe this dynamically?37:07
Experimental setup: Homodyne detection37:31
Vortex Pairs in the wake of an obstacle37:56
Vortex nucleation regime39:04
Superfluidity and Bogoliubov excitations39:45
Naive picture of the ghost branch40:23
Bogoliubov transformation41:19
Heterodyne Four Wave Mixing41:44
Polariton Ghost Branch42:36
Take home message44:01
The dream team44:33
I would to thank our dear theorists44:51
You may wonder about the training at LOEQ45:05
Half vortices as building blocks of topological defects45:27
How to prepare traps for polaritons?48:12
Lateral confinement of polaritons48:23