Seminarium Optyczne

Stochastic classical field model for polariton condensates: coherence and superfluidity abstract: Microcavity polaritons are quasi-particles in the solid state that are a coherent superposition of a quantum well exciton and a microcavity photon. Thanks to their light mass and collisional relaxation, they are well suited to achieve Bose-Einstein condensation in the solid state at standard cryogenic temperatures. In state of the art microcavities, the polariton life time is not long enough to ensure full thermalization of polariton condensates, so that an equilibrium statistical description does not hold. This poses the theoretical challenge to develop a tractable model that describes this nonequilibrium system. We present a stochastic classical field model for polariton condensates [1] and discuss their coherence and superfluid properties. The model is based on the truncated Wigner approximation for the condensate, coupled to a classical rate equation for the excitonic reservoir and describes the coherence properties of the condensate across the threshold. Because the model describes the time-dependent dynamics of the polariton condensate, it allows for the description of the coherence buildup. We compare our simulations with recent experiments at EPFL. Finally, we discuss how to investigate the superfluidity of polariton condensates through the vortex dynamics.