Eur. Phys. J. D 18, 353-364 (2002)
DOI: 10.1140/epjd/e20020041

Spatial diffusion in a periodic optical lattice: revisiting the Sisyphus effect

L. Sanchez-Palencia¹, P. Horak² and G. Grynberg<sup>1

1</sup>  Laboratoire Kastler-Brossel, Département de Physique de l'École Normale Supérieure, 24 rue Lhomond, 75231 Paris Cedex 05, France
²  Institut für Theoretische Physik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria

lsanchez@lkb.ens.fr

(Received 8 August 2001 and Received in final form 6 November 2001)

Abstract
We numerically study the spatial diffusion of an atomic cloud experiencing Sisyphus cooling in a three-dimensional lin lin optical lattice in a broad range of lattice parameters. In particular, we investigate the dependence on the size of the lattice sites which changes with the angle between the laser beams. We show that the steady-state temperature is largely independent of the lattice angle, but that the spatial diffusion changes significantly. It is shown that the numerical results fulfill the Einstein relations of Brownian motion in the jumping regime as well as in the oscillating regime. We finally derive an effective Brownian motion model from first principles which gives good agreement with the simulations.

PACS
32.80.Pj - Optical cooling of atoms, trapping.
42.50.Vk - Mechanical effects of light on atoms, molecules, electrons, and ions.


© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2002

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