Dynamics and phase evolution of Bose-Einstein condensates in   one-dimensional optical lattices
  We report experimental results on the dynamics and phase evolution of Bose-Einstein condensates in 1D optical lattices. The dynamical behaviour is studied by adiabatically loading the condensate into the lattice and subsequently switching off the magnetic trap. In this case, the condensate is free to expand inside the periodic structure of the optical lattice. The phase evolution of the condensate, on the other hand, can be studied by non-adiabatically switching on the periodic potential. We observe decays and revivals of the interference pattern after a time-of-flight. 
O. Morsch and M. Cristiani and J.H. M\"uller and D. Ciampini and E.   Arimondo