2012/02/28 by R. Combescot, M. Combescot · 1 citation
Physics and Astronomy · #cond-mat.quant-gas #quant-ph
paper · pdf · doi:10.1103/physrevlett.109.026401
4 pages, typo corrected
arxiv created 2012/02/28 · arxiv updated 2013/05/29
It has been recently suggested that the Bose-Einstein condensate formed by excitons in the dilute limit must be dark, i.e., not coupled to photons. Here, we show that, under a density increase, the dark exciton condensate must acquire a bright component due to carrier exchange in which dark excitons turn bright. This however requires a density larger than a threshold which seems to fall in the forbidden region of the phase separation between a dilute exciton gas and a dense electron-hole plasma. The BCS-like condensation which is likely to take place on the dense side, must then have a dark and a bright component - which makes it "gray". It should be possible to induce an internal Josephson effect between these two coherent components, with oscillations of the photoluminescence as a strong proof of the existence for this "gray" BCS-like exciton condensate.