Volume 81, Number 3, February 2008
Article Number 33001
Number of page(s) 6
Section Atomic, Molecular and Optical Physics
Published online 03 January 2008
EPL, 81 (2008) 33001
DOI: 10.1209/0295-5075/81/33001

Influence of the lattice topography on a three-dimensional, controllable Brownian motor

H. Hagman, C. M. Dion, P. Sjölund, S. J. H. Petra and A. Kastberg

Department of Physics, Umeå University - SE-90187 Umeå, Sweden

received 14 May 2007; accepted in final form 2 December 2007; published February 2008
published online 3 January 2008

We study the influence of the lattice topography and the coupling between motion in different directions, for a three-dimensional Brownian motor based on cold atoms in a double optical lattice. Due to controllable relative spatial phases between the lattices, our Brownian motor can induce drifts in arbitrary directions. Since the lattices couple the different directions, the relation between the phase shifts and the directionality of the induced drift is non-trivial. Here is therefore this relation investigated experimentally by systematically varying the relative spatial phase in two dimensions, while monitoring the vertically induced drift and the temperature. A relative spatial phase range of $2\pi \times 2\pi $ is covered. We show that a drift, controllable both in speed and direction, can be achieved, by varying the phase both parallel and perpendicular to the direction of the measured induced drift. The experimental results are qualitatively reproduced by numerical simulations of a simplified, classical model of the system.

32.80.Lg - Mechanical effects of light on atoms, molecules, and ions.
05.40.Jc - Brownian motion.
32.80.Pj - Optical cooling of atoms; trapping.

© EPLA 2008