Optical molasses, laser traps, and ultracold atoms

William D. Phillips, Paul D. Lett, S. L. Rolston +7 more

Paul S. Julienne

Intense laser fields in optical neutral-atom traps can have a profound effect on collision cross sections at ultracold temperatures, $T<{10}^{\ensuremath{-}3}$ K. A simple model is developed for the long-range interatomic potentials of two field-dressed atoms. Field dressing ensures that the cross section for associative ionization of two ultracold Na atoms is large in an optical trap, but the cross section is predicted to be about 4 orders of magnitude smaller in optical molasses.

Paul S. Julienne, Robert Heather

Specific molecular mechanisms are proposed for associative ionization collisions of ultracold sodium atoms in a hybrid optical trap. When an intense, strongly detuned optical trap laser is on, the ionization rate is modulated by molecular bound-state resonances which are strongly affected by field dressing. When the weak, slightly detuned optical molasses lasers are on to provide cooling, an excitation mechanism which produces the two excited atoms at large internuclear separation in different hyperfine states accounts for the lower observed ionization rate.

I. Peterson

N. P. Bigelow, Mara Goff Prentiss

We derive expressions for the damping rate for a two-level atom trapped in the antinodes of an optical interference pattern. We find that the decay rate is much slower than the rate for untrapped atoms in optical molasses. Although the velocity of untrapped atoms decays exponentially in time, the velocity of trapped atoms decays only as t(-(1/2)). We show that the slow damping rate can be circumvented by the addition of a traveling-wave component to the molasses standing wave and discuss how these results can be extended to multilevel atoms.

Harald Schadwinkel, D. Haubrich, A. Hope +1 more