Theory of polariton condensation

Lately, some novel experiments with planar optical microcavities make use of the mixing of excitons with photons to create composite bosons called polaritons that have a very light mass, and are thus a good candidate for high-temperature Bose condensation. Good evidence for spontaneous coherence has now been obtained.\footnote{J. Kasprzak, et al.Nature, 443, 409-415 (2006).} There are special issues to resolve\footnote{J. Keeling, F. M. Marchetti, M. H. Szymanska, P. B. Littlewood, Semiconductor Science and Technology, 22, R1-26 (2007).} considering the effects of low dimensionality, disorder, strong interactions, and especially strong decoherence associated with decay of the condensate into environmental photons\footnote{M. H. Szymanska, J. Keeling, P. B. Littlewood, Physical Review B 75, 195331 (2007).} --- since the condensate is a special kind of laser.