Directed transport of Bose-Einstein Condensates with kicked interactions

We study the response of a Bose-Einstein Condensate in a delta-kicked optical lattice ratchet potential, with delta-kicked interactions, at quantum resonances. Our results reveal a strong dependency on the kicking strength K and the interaction parameter g. A critical curve in the (K, g)-space separating quasi-periodicity from full chaos shows that full chaos can be easily achieved for stronger interactions. In the full chaos regime, large currents including current reversals are generated and the current spectrum symmetry is broken. Outside the stability window, |g| <= 1, the directed transport is no longer guaranteed. Experiments are possible thanks to recent progress in optical lattices and the possibility of time-modulating Feshbach-resonance.