Optomechanical generation of a photonic Bose-Einstein condensate

We propose to thermalize a low-dimensional photon gas and obtain photonic Bose-Einstein condensation by optomechanical interactions in a microscopic optical cavity, with a single longitudinal mode and many transverse modes. The geometry of the short cavity is such that it provides a low-frequency cutoff at a photonic energy far above the thermal energy, so that thermal emission of photons is suppressed and the photon number is conserved. While previous experiments on photonic Bose-Einstein condensation have used dye molecules for photon gas thermalization, we here investigate thermalization owing to interactions with thermally fluctuating nanomechanical oscillators forming the cavity mirrors. In the quantum degenerate regime, the nanomechanical cavity converts broadband optical radiation into tuneable coherent radiation.