Tuesday, February 28, 2012

1202.5976 (R. Combescot et al.)

"Gray" BCS condensate of excitons and internal Josephson effect    [PDF]

R. Combescot, M. Combescot
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 in 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.
View original: http://arxiv.org/abs/1202.5976

No comments:

Post a Comment