Hanbury Brown Twiss effect for ultracold quantum gases
  We have studied 2-body correlations of atoms in an expanding cloud above and below the Bose-Einstein condensation threshold. The observed correlation function for a thermal cloud shows a bunching behavior, while the correlation is flat for a coherent sample. These quantum correlations are the atomic analogue of the Hanbury Brown Twiss effect. We observe the effect in three dimensions and study its dependence on cloud size. 
M. Schellekens, R. Hoppeler, A. Perrin, J. Viana Gomes, D. Boiron, A.   Aspect, C. I. Westbrook