Superfluid Bloch dynamics in an incommensurate optical lattice

We investigate the interplay of disorder and interactions in the accelerated transport of a Bose–Einstein condensate through an incommensurate optical lattice. We show that interactions can effectively cancel the damping of Bloch oscillations (BOs) due to the disordered potential and we provide a simple model to qualitatively capture this screening effect. We find that the characteristic interaction energy, above which interactions and disorder cooperate to enhance, rather than reduce, the damping of BOs, coincides with the average disorder depth. This is consistent with results of a mean-field simulation. (paper)