In a pumped dye-filled microcavity, photns thermalize with the dye molecules by repeated absorption and emission. For sufficiently strong pumping, a photonic Bose-Einstein condensate forms, where the majority of photons occupy the lowest-energy mode.
Master equation: photon number nν
Quantum detector for enantiomeric excess
The presence of chiral molecules can be detected from the induced circular polarisation of the condensate.