Experimental Realization of Quantum-Resonance Ratchets

Abstract

Quantum-resonance ratchets associated with the periodically kicked particle are experimentally realized for the first time. This is achieved by using a Bose-Einstein condensate exposed to a pulsed standing light wave and prepared in an initial state differing from the usual plane wave. Both the standing-wave potential and the initial state have a point symmetry around some center and the ratchet arises from the non-coincidence of the two centers. The dependence of the directed quantum transport on the quasimomentum is studied. A detailed theoretical analysis is used to explain the experimental results.Comment: Accepted for publication in Physical Review Letters (November 2007