  We demonstrate quantum resonance ratchets created with Bose-Einstein
condensates exposed to pulses of an off-resonant standing light wave. We show
how some of the basic properties of the ratchets are controllable through the
creation of different initial states of the system. In particular, our results
prove that through an appropriate choice of initial state it is possible to
reduce the extent to which the ratchet state changes with respect to time. We
develop a simple theory to explain our results and indicate how ratchets might
be used as part of a matter wave interferometer or quantum-random walk
experiment.
