Atom-Optics Billiards: Non-linear dynamics with cold atoms in optical   traps
  We present a new experimental system (the ``atom-optics billiard'') and demonstrate chaotic and regular dynamics of cold, optically trapped atoms. We show that the softness of the walls and additional optical potentials can be used to manipulate the structure of phase space. 
Ariel Kaplan, Mikkel Andersen, Nir Friedman and Nir Davidson