Stuttgart 2012 – scientific programme
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A: Fachverband Atomphysik
A 35: Ultra-cold atoms, ions and BEC III
A 35.6: Talk
Thursday, March 15, 2012, 15:15–15:30, V47.02
Sympathetic cooling of ions to ultralow energies — •Artjom Krükow, Andreas Brunner, Arne Härter, Stefan Schmid, Wolfgang Schnitzler, and Johannes Hecker Denschlag — Institut für Quantenmaterie, Universität Ulm, Albert-Einstein Allee 45, 89081 Ulm, Germany
We investigate the interaction of a laser-cooled trapped ion (138Ba+ or 87Rb+) with an ultracold cloud of optically confined 87Rb atoms. The ion is held in a linear Paul trap and is immersed in the center of the cold atomic cloud. The atom-ion interaction gives rise to a long range attractive 1/r4 polarization potential. Charge transfer processes and elastic scattering were observed at millikelvin collision energies [1,2]. The collision energy scale is given by the effect of stray electric fields on ions in a dynamic Paul trap, namely causing ion micromotion [3]. Using field compensation techniques, we achieve sympathetic cooling of the ion to Ba+ sub-Doppler temperatures (<300 µK) and examine the influence of ion micromotion energy over a wide range. By decreasing the ion temperatures even further we are aiming at novel experiments, such as the creation of mesoscopic atom-ion bound states [4] or the production of ultracold, charged molecules in a well-defined quantum state.
[1] S. Schmid et al, Phys. Rev. Lett. 105, 133202 (2010)
[2] C. Zipkes et al, Phys. Rev. Lett. 105, 133201 (2010)
[3] D. Berkeland et al, J. Appl. Phys. 83, 10 (1998)
[4] R. Côté et al., Phys. Rev. Lett. 89, 093001 (2002)