Phase coherence length of a Bose-Einstein condensate
  We report on the measurement of the momentum distribution of an elongated Bose-Einstein condensate. A broadening of the distribution with increasing temperature is observed, which is clear evidence for phase fluctuations in the sample. 
F. Gerbier, S. Richard, J. H. Thywissen, M. Hugbart, P. Bouyer, A.   Aspect