Control of Interaction-Induced Dephasing of Bloch Oscillations

Authors :: Gustavsson, M.
Haller, E.
Mark, M. J.
Danzl, J. G.
Rojas-Kopeinig, G.
Naegerl, H. -C.
Publication Year :: 2007
Abstract: We report on the control of interaction-induced dephasing of Bloch oscillations for an atomic Bose-Einstein condensate in an optical lattice under the influence of gravity. When tuning the strength of the interaction towards zero by means of a Feshbach resonance, the dephasing time is increased from a few to more than twenty thousand Bloch oscillation periods. We quantify the dephasing in terms of the width of the quasi-momentum distribution and measure its dependence on time for different values of the scattering length. Minimizing the dephasing allows us to realize a BEC-based atom interferometer in the non-interacting limit. We use it for a precise determination of a zero-crossing for the atomic scattering length and to observe collapse and revivals of Bloch oscillations when the atomic sample is subject to a spatial force gradient.<br />Comment: 4 pages, 5 figures