The dynamics of a Bose-Einstein condensate nonadiabatically loaded into a one-dimensional optical lattice is studied by analyzing the phase coherence between sites along the lattice as well as the radial profile of the condensate after a time-of flight. A simple model is proposed that predicts the short-time dephasing as a function of the condensate parameters. In the radial direction, heavily damped oscillations are observed, as well as an increase in the condensate temperature. These findings are interpreted as a rethermalization due to dissipation of the initial condensate excitations into high-lying modes.

• Received 5 August 2002

DOI:https://doi.org/10.1103/PhysRevA.67.031603