Spontaneous Coherence Buildup in a Polariton Laser

Abstract

We describe theoretically the spontaneous buildup of the second-order coherence of light emitted by microcavities in the regime of polariton lasing. This effect reveals important changes in quantum statistics of exciton polaritons in the course of their condensation. The coherence may start rising even if the polaritons do not interact with each other, e.g., in a low density regime. It happens due to correlations between occupation numbers of the ground and excited states in the microcavity.