Modern Optics and Spectroscopy
David Snoke, University of Pittsburgh
Bose-Einstein condensation of polaritons in microcavities
October 2 , 2007
12:00 noon - 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.
TUESDAYS, 12:00-1:00, GRIER ROOM (34-401)
Refreshments served following the seminar
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Co-sponsored by the George R. Harrison
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