[MOS] MOS October 2, 2007

[Zina Queen]

Seminar on
Modern Optics and Spectroscopy


David Snoke,
University of Pittsburgh

Bose-Einstein condensation of polaritons in microcavities

October 2, 2007

12:00 - 1:00 p.m.
Grier Room 34-401



Polaritons are bosonic quasiparticles which are a superposition of 
photons and excitons in a solid. In microcavity structures, they have 
effective mass and a repulsive interaction, and can move freely in a 
two-dimensional plane, so that they can be treated as a weakly 
interacting Bose gas.  We have recently demonstrated (Science 316, 
1007 (2007)) trapping of polaritons in a harmonic potential; under 
these conditions the polaritons show a number of effects associated 
with Bose-Einstein condensation: a bimodal momentum distribution, a 
spatial condensation in the center of the trap, spontaneous symmetry 
breaking as seen in polarization of the emitted light, and long-range 
coherence as seen in intererence patterns of the emitted light. 
Although the polaritons exist for only a few picoseconds, the analogy 
with a weakly interacting atomic gas is good, and the effects of 
incomplete equilibrium do not destroy the condensate completely.
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