Phases and phase transitions in the ensemble of photons and dye molecules

Realization of Bose-Einstein (quasi-)condensation of light in 2D [1] provides a new platform for studying novel phases and phase transitions with no analogy in other condensed matter systems. One of the phases is the condensate of photon pairs induced solely by the orientational disorder of the dye molecules. This phase does not require any attraction between photons. The condensation of photons can proceed through the phase separation effect induced by equilibration of the dye molecules simultaneously with the formation of the photonic condensate.

[1] J. Klaers, F. Vewinger and M. Weitz, Nature Phys. 6 , 512 (2010); J. Klaers, J. Schmitt, F.
Vewinger and M. Weitz, Nature 468, 545 (2010).