A three-dimensional Brownian motor, realised with symmetric optical lattices

A. Kastberg, C. M. Dion, H. Hagman, and M. Zelán

Department of Physics, Umeå University, SE-901 87 Umeå, Sweden

A three-dimensional Brownian motor is realised using lasercooled caesium atoms trapped in a system of two static, and individually symmetric, optical lattices; a so-called double optical lattice. Isotropic fluctuations, emanating from light scattering, are rectified, and the diffusion of the ensemble of atoms is biased, with a resulting constant velocity that is controllable both in direction and magnitude. The working principle of the Brownian motor can be seen as a pulsation between two different potentials, both symmetric but around different points. The correlation between interferometric spatial offsets, and imbalance in optical pumping rates, leads to a spatio-temporal asymmetry sufficient for generating a controlled, directed motion.

This article has been published in Physica Status Solidi B 246, 999 (2009).

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