Ordered dissipative structures in exciton systems in semiconductor quantum wells

A phenomenological theory of exciton condensation in conditions of inhomogeneous excitation is proposed. This theory is a classical theory of phase transitions in real space (not in momentum space), generalized for the case of particles with finite lifetimes-i.e., for the case of a nonequilibrium system. We study the development of a ring of exciton luminescence at macroscopical distances from the central excitation spot in double quantum wells. At certain conditions, the ring breaks down into a periodical array of islands of a condensed phase. The transition between the fragmented and the continuous ring is considered. Assuming a defect in the structure, a possibility of a localized island of the condensed phase in a fixed position outside of the ring is shown. The temperature dependence of the effects has been considered as well.