Collapse and Revival of the Matter Wave Field of a Bose-Einstein   Condensate
  At the heart of a Bose-Einstein condensate lies its description as a single giant matter wave. Such a Bose-Einstein condensate represents the most "classical" form of a matter wave, just as an optical laser emits the most classical form of an electromagnetic wave. Beneath this giant matter wave, however, the discrete atoms represent a crucial granularity, i.e. a quantization of this matter wave field. Here we show experimentally that this quantization together with the cold collisions between atoms lead to a series of collapses and revivals of the coherent matter wave field of a Bose-Einstein condensate. We observe such collapses and revivals directly in the dynamical evolution of a multiple matter wave interference pattern, and thereby demonstrate a striking new behaviour of macroscopic quantum matter. 
Markus Greiner (1 and 2), Olaf Mandel (1 and 2), Theodor W. Haensch (1   and 2) and Immanuel Bloch (1 and 2) ((1) Ludwig-Max...