Phase fluctuations and first-order correlation functions of dissipative   Bose-Einstein condensates
  We investigate the finite lifetime effects on first-order correlation functions of dissipative Bose-Einstein condensates. By taking into account the phase fluctuations up to all orders, we show that the finite lifetime effects are neglible for the spatial first-order correlation functions, but have an important effect on the temporal correlations. As an application, we calculate the one-particle density matrix of a quasi-condensate of photons. Finally, we also consider the photons in the normal state and we demonstrate that the finite lifetime effects decrease both the spatial and temporal first-order correlation functions. 
A.-W. de Leeuw, H.T.C. Stoof, and R.A. Duine
cond-mat.quant-gas