Seminar on
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


Abstract:

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 Spectroscopy Laboratory,
the Department of Electrical Engineering and Computer Science and
the School of Science, Massachusetts Institute of Technology.