1209.4573 (Bryan Nelsen et al.)

Coherent Flow and Trapping of Polariton Condensates with Long Lifetime    [PDF]

Bryan Nelsen, Gangqiang Liu, Mark Steger, David W. Snoke, Ryan Balili, Ken West, Loren Pfeiffer

We report new results of Bose-Einstein condensation of polaritons in specially designed microcavities with very high quality factor, on the order of 10^6, giving polariton lifetimes of the order of 100 ps, which is much longer than their thermalization time. We see qualitatively different physics from previous experiments with polaritons with much shorter lifetime, in part because the longer lifetime in these new structures allows the polaritons to travel macroscopic distances up to a millimeter. We observe novel effects in three regimes of polariton density. At low density, we see classical ballistic motion over hundreds of microns. From this, we obtain a direct measurement of the mean free scattering time of the polaritons. At moderate density, we see coherent wave-like motion over long distance. This appears as a continuous transition, and can be described in terms of quasicondensation. At high density, we see a very sharp transition to a trapped state with very high coherence indicative of equilibrium BEC. We compare our results to previous experiments on transport of polaritons.

View original: http://arxiv.org/abs/1209.4573