%T Rectifying fluctuations in an optical lattice %L discovery9658 %J PHYS REV LETT %N 7 %V 93 %A PH Jones %A M Goonasekera %A F Renzoni %K STOCHASTIC RESONANCE, BROWNIAN MOTORS, THERMAL RATCHETS, DRIVEN SYSTEMS, RECTIFICATION, DIFFUSION, TRANSPORT, SYMMETRY, SQUIDS, ATOMS %X We have realized a Brownian motor by using cold atoms in a dissipative optical lattice as a model system. In our experiment the optical potential is spatially symmetric and the time symmetry of the system is broken by applying appropriate zero-mean ac forces. We identify a regime of rectification of forces and a regime of rectification of fluctuations, the latter corresponding to the realization of a Brownian motor. %D 2004 %P ? - ? %I AMERICAN PHYSICAL SOC