COHERENCE PROPERTIES OF BOSE-EINSTEIN CONDENSATES AND ATOM LASERS

We discuss various aspects of coherence of a Bose-Einstein condensate, and summarize the experimental evidence obtained thus far. It is shown that the mean-field energy of a condensate is a measure of second-order coherence. ``Release-energy'' measurements therefore provide direct evidence of the suppression of density fluctuations in a condensate compared to a thermal cloud.