We experimentally study the density transport properties of a one-dimensional quantum-degenerate Bose gas in an optical lattice. After exciting dipole oscillations along the axis of the gas/lattice, we observe a damped response. The behavior of the oscillations depends strongly on the depth of the optical lattice with super-critical damping occurring at lattice depths greater than approximately two recoil energies. The Bose-Hubbard model which describes this system for deep lattices, predicts a superfluid-Mott insulator transition at approximately four recoil energies, but it is not clear that the Bose-Hubbard model predicts dissipation in the vicinity of the transition.

Contact Steven L. Rolston.