Photon condensates in microstructured trapping potentials

Bose-Einstein condensation, the macroscopic ground state occupation of bosonic particles at low temperature and high density, has previously been observed for cold atomic gases and solid-state quasiparticles. In recent work, Bose-Einstein condensation of photons has been realized in a dye-filled optical microcavity at room temperature [1, 2]. The short mirror spacing of the curved mirror microcavity introduces a low-frequency cutoff, and thermal contact to the dye-solution is achieved by subsequent absorption and re-emission processes.