Bose-Einstein condensation of excitons.

Abstract

Experimental results concerning ballistic excitonic transport in high quality cuprite single crystals are presented and discussed. The onset conditions of this anomalous transport, in the form of a packet propagating at near sound velocity, is compatible with theoretical predictions for Bose-Einstein condensation of n = 1 paraexcitons. Experiments involving the interaction between two packets reveal coherence properties, in agreement with an interpretation assuming an exciton Bose-Einstein condensate as the origin of the packet. The amplification of the packet by thermal excitons and the creation of a stationary condensate in the form of a filament are discussed in terms of radiationless exciton scattering induced by the condensate.