Formation of molecules from a Cs Bose-Einstein condensate (9 pages)

Vladimir Yurovsky, A. Ben‐Reuven

Michael W. Jack

Bogdan Damski

Vladimir Yurovsky, A. Ben‐Reuven

Conversion of an expanding Bose-Einstein condensate of Cs atoms to a molecular one with an efficiency of more than 30% was observed recently in experiments by M. Mark et al. [Europhys. Lett. 69, 706 (2005)]. The theory presented here describes the experimental results. Values of resonance strength of 8 mG and rate coefficients for atom-molecule deactivation of $1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}11}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{3}∕\mathrm{s}$ and molecule-molecule one of $1.5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{3}∕\mathrm{s}$ are estimated by a fit of the theoretical results to the experimental data. Near the resonance, where the highest conversion efficiency was observed, the results demonstrate strong sensitivity to the magnetic field ripple and inhomogeneity. A conversion efficiency of about 60% is predicted by non-mean-field calculations for densities and sweep rates lower than the ones used in the experiments.

Carl J. Williams, Paul S. Julienne

In recent years, much progress has been made in producing and manipulating ultracold atoms in Bose-Einstein condensates (BECs). But, as Williams and Julienne explain in this Perspective, molecules are poor candidates for the laser cooling techniques commonly used to produce BECs. Many groups are trying to devise techniques for making ultracold molecules. A technique reported by Wynar et al. (page 1016) has allowed the first observation of molecule formation in a BEC, and may ultimately be able to produce a pure molecular condensate.