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Q: Quantenoptik

Q 17: Poster: Cooling and Trapping

Q 17.32: Poster

Mittwoch, 4. April 2001, 12:30–15:00, AT2

Homo- and heteronuclear spin-changing collisions between ultracold atoms in an optical dipole trap — •Stephan Kraft¹, Marcel Mudrich¹, Kilian Singer¹, Wendel Wohlleben¹, Allard Mosk¹, Rudi Grimm², and Matthias Weidemüller¹ — ¹Max-Planck-Institut für Kernphysik, 69029 Heidelberg, Germany — ²Institut für Experimentalphysik, Universität Innsbruck, Austria

We report on inelastic hyperfine-changing collisions between ultracold Li-Li, Cs-Cs and Li-Cs atoms in a quasi-electrostatic optical dipole trap (QUEST). Li and Cs are transfered from a magneto-optical trap into the QUEST, created by a focused 100-W CO₂-laser beam at a wavelength of 10.6 µ m [1]. Due to the very low restgas pressure we achieve very long storage times for Li and Cs in the lowest hyperfine state (∼100 s) [2]. Transfering one species in the upper hyperfine state decreases the lifetime dramatically by spin-changing collisions with an energy release exceeding the trap depth. The measured cross section for Cs-Cs collisions agrees well with previous experiments. Rapid Li decay indicates a very large cross section for inelastic Li-Li and Li-Cs collisions. In future experiments we will investigate the magnetic field dependence of the cross section which may reveal possible scattering resonances.

[1] Poster by M. Mudrich et al.

[2] H. Engler et al., Phys. Rev. A 62, 031402 (R) (2000).