Excitations of optically driven atomic condensate in a cavity: theory of photodetection measurements

Understand

Recent experiments have demonstrated an open system realization of the Dicke quantum phase transition in the motional degrees of freedom of an optically driven Bose-Einstein condensate in a cavity.

• Relevant collective excitations of this light-matter system are polaritonic in nature, allowing access to the quantum critical behavior of the Dicke model through light leaking out of the cavity.
• This opens the path to using photodetection based quantum optical techniques to study the dynamics and excitations of this elementary quantum critical system.
• We first discuss the photon flux observed at the cavity face and find that it displays a different scaling law near criticality than that obtained from the mean field theory for the equivalent closed system.