A cold-atom ratchet interpolating between classical and quantum dynamics

R. K. Shrestha, W. K. Lam, J. Ni, G. S. Summy

Published 2012-10-20, updated 2013-06-03Version 4

We study the crossover between classical and quantum dynamics by observing the behavior of a quantum ratchet created by exposing a Bose-Einstein condensate to short pulses of a potential which is periodic in both space and time. Such a ratchet is manifested by a directed current of particles, even though there is an absence of a net bias force. We confirm that the ratchet behavior can under certain circumstances be the same in both regimes. We demonstrate that this behavior can be understood using a single variable containing many of the experimental parameters and thus the ratchet current is describable using a single universal scaling law.