Time dependence of laser cooling in optical latticesC. M. Dion, P. Sjölund, S. J. H. Petra, S. Jonsell and A. Kastberg
Department of Physics, Umeå University - SE-901 87 Umeå, Sweden
received 14 June 2005; accepted in final form 6 September 2005
published online 23 September 2005
We study the dynamics of the cooling of a gas of caesium atoms in an optical lattice, both experimentally and with 1D full-quantum Monte Carlo simulations. We find that, contrary to the standard interpretation of the Sisyphus model, the cooling process does not work by a continuous decrease of the average kinetic energy of the atoms in the lattice. Instead, we show that the momentum of the atoms follows a bimodal distribution, the atoms being gradually transferred from a hot to a cold mode. We suggest that the cooling mechanism should be depicted in terms of a rate model, describing the transfer between the two modes along with the processes occurring within each mode.
32.80.Pj - Optical cooling of atoms; trapping.
05.10.Ln - Monte Carlo methods.
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