Collective fluid dynamics of a polariton condensate in a semiconductor microcavity

Polariton condensates It has been predicted that excitons, bound pairs of electrons and holes, should form Bose–Einstein-like condensates at relatively high temperatures. Recently, evidence has been reported of a BEC in a semiconductor microcavity formed by exciton-polaritons, which are a mixture of excitons and photons. Superfluid-like behaviour is expected in such polariton condensates, though it would be of an unusual character as microcavity polaritons are short-lived, so the condensates are not in thermal equilibrium. Amo et al. have developed a pulsed optical excitation technique to set a microcavity polariton condensate in motion and they observe clear manifestations of collective dynamics with superfluid characteristics, such as flow without resistance when crossing a defect. This work points into a new direction to study the dynamics of out-of-equilibrium condensates.