Exciton-polariton anticrossing and spontaneous coherence in a microcavity
Exciton-polaritons are light-matter quasiparticles formed by strong coupling between quantum-well excitons and cavity photons. The coupling Ω produces an anticrossing splitting (Rabi splitting) of the upper (UP) and lower (LP) polariton branches. Above the lasing threshold P > Pth, the LP branch condenses into a macroscopic coherent state — a non-equilibrium Bose-Einstein condensate.