Damped Bloch oscillations of Bose–Einstein condensates in disordered potential gradients

We investigate both experimentally and theoretically disorderinduced damping of Bloch oscillations of Bose–Einstein condensates in optical lattices. The spatially inhomogeneous force responsible for the damping is realized by a combination of a disordered optical and a magnetic gradient potential. We show that the inhomogeneity of this force results in a broadening of the quasimomentum spectrum, which in turn causes damping of the centreof-mass oscillation. We quantitatively compare the obtained damping rates to the simulations using the Gross–Pitaevskii equation. Our results are relevant for high precision experiments on very small forces, which require the observation of a large number of oscillation cycles. 3 Author to whom any correspondence should be addressed. New Journal of Physics 10 (2008) 045027 1367-2630/08/045027+13$30.00 © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft