Brillouin propagation modes in optical lattices: Interpretation in terms of nonconventional stochastic resonance

Brillouin propagation modes in optical lattices were observed, and a scheme was proposed for the detection of these modes. The Brillouin modes examined were sustained by a medium of noninteracting particles. The transport of atoms in the optical lattice was studied by observing the atomic cloud expansion with a charge coupled device camera. Results indicated that in the presence of noise, the Brownian motion of a system of particles in a periodic potential could be turned in a motion at a well-defined velocity by the application of a weak moving modulation.