Quantum dynamics of exciton lasers

We analyze the quantum dynamics of an exciton boser or laser - a device that generates a coherent population of nonequilibrium excitons. After deriving the master equation for the exciton boser in the Born-Markov approximation, we use a stochastic wave function approach to demonstrate that an approximately coherent state of excitons is generated from the vacuum state. The quantum theory that we develop allows us to analyze the effects of exciton-exciton interactions on coherent state formation. We demonstrate that the line width reduction obtained in a boser is limited by the strength of these interactions.