Compression of optically dense and cold atomic cloud

by short pulse of laser light

Lev Khaykovich and Nir Davidson

We analyze the light-induced atom-atom interactions in optically thick atomic clouds and show that, when the laser frequency is on-resonance with the atomic transition, they become attractive. On the basis of this analysis we propose and demonstrate a novel scheme to compress a cold and dense atomic cloud with a short on-resonance laser pulse. The compression force arises from attenuation of the laser light by the atomic cloud. The following free propagation of the atoms shows a lenslike behavior that yields a transient density increase at the focal time, where neither laser nor magnetic field perturbations exist. A cooling pulse which is applied at the focal time of this lens, restores the initial temperature of atoms, and hence the phase-space density is increased. Finally, we adopt our compression scheme to a quasi-steady-state mode by temporally chopping it with the cooling and trapping beams of a magneto-optical trap.

"Compression of a cold atomic cloud by on-resonance laser light" L. Khaykovich and N. Davidson, J. Opt. Soc. Am. B 16, 702 (1999). (PDF)

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