The Gas Liquid Transition of Excitons: from Bose glass to BEC
In this talk I shall review our work on the gas-liquid transition of 2D excitons in GaAs quantum wells. Below a critical temperature and above a critical density this system undergoes a phase transition to a liquid state. By employing a variety of optical spectroscopy tools we map the phase diagram of the system, and show that the liquid is a Bose Einstein condensate of dark excitons (exciton state which is not coupled to light).
We find that the liquid phase is fragmented below Tc and the spatial fluctuations decay as the temperature is lowered, manifesting a continuous transition from a Bose glass to BEC.