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Vortices and superfluidity in exciton-polariton condensates
Published on 2014-04-044328 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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Presentation
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