Eur. Phys. J. D 28, 135-147 (2004)
https://doi.org/10.1140/epjd/e2003-00293-3

Stochastic dynamics of the magneto-optical trap

Laboratoire de Physique des Lasers, Atomes et Molécules, Unité mixte du CNRS, Centre d'Études et de Recherches Lasers et Applications, Bâtiment P5, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq Cedex, France

Corresponding author: ^a daniel.hennequin@univ-lille1.fr

Received: 4 March 2003
Revised: 18 June 2003
Published online: 28 October 2003

Abstract

The cloud of cold atoms obtained from a magneto-optical trap is known to exhibit two types of instabilities in the regime of high atomic densities: stochastic instabilities and deterministic instabilities. In the present paper, the experimentally observed stochastic dynamics is described extensively. It is shown that it exists a variety of dynamical behaviors, which differ by the frequency components appearing in the dynamics. Indeed, some instabilities exhibit only low frequency components, while in other cases, a second time scale, corresponding to a higher frequency, appears in the motion of the center of mass of the cloud. A one-dimensional stochastic model taking into account the shadow effect is shown to be able to reproduce the experimental behavior, linking the existence of instabilities to folded stationary solutions where noise response is enhanced. The different types of regimes are explained by the existence of a relaxation frequency, which in some conditions is excited by noise.