Berlin 2014 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 39: Ultracold atoms, ions and BEC IV (with A)

Q 39.6: Talk

Thursday, March 20, 2014, 11:45–12:00, BEBEL E34

Observation of atom-ion charge transfer beyond the Langevin regime — •Amir Mohammadi, Artjom Krükow, Arne Härter, Tobias Schnetzer, Joschka Wolf, and Johannes Hecker Denschlag — Universität Ulm, Institut für Quantenmaterie, Albert-Einstein-Allee 45, D-89069 Ulm, Deutschland

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. Due to the interaction potential 1/r⁴ charge transfer collisions usually occur at an energy independent rate [1]. This leads to an energy independent charge transfer rate which has been confirmed experimentally [2, 3]. In our experiments we observe a deviation from this behavior as we find strong energy dependence in the charge transfer rate at kinetic energies in the sub-mK range. At these very low kinetic energies an additional charge transfer channel opens up due to the increasing importance of three-body atom-atom-ion recombination [4]. We present first experimental findings of this novel charge transfer mechanism.

[1] P. Langevin, Ann. Chim. Phys. 5, 245 (1905)

[2] Andrew T. Grier et al., Phys. Rev. Lett. 102, 223201 (2009)

[3] Felix H. J. Hall et al., Phys. Rev. Lett. 107, 243202 (2011)

[4] Arne Härter et al., Phys. Rev. Lett. 109, 123201 (2012)