Hannover 2013 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 6: Ultracold atoms and molecules

Q 6.3: Talk

Monday, March 18, 2013, 11:45–12:00, A 310

Feedback on a single atom using heterodyne detection — Christian Sames, Haytham Chibani, Christoph Hamsen, Anna Caroline Eckl, Paul Altin, •Tatjana Wilk, and Gerhard Rempe — Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Str. 1, D-85748 Garching

An optical cavity can be used as a kind of intensifier to study radiation features of an atom, which are hard to detect in free space, like squeezing [1]. Such experiments make use of strong coupling between atom and cavity mode. Experimentally, strong coupling requires the atom to be well localized in the cavity mode. This can be achieved using feedback on the atomic motion: since the atom-cavity coupling depends on the atomic position within the mode, the field of a probe beam transmitted through the cavity varies strongly when the atom moves. The intensity of an intracavity dipole trap can then be switched in synchronism with the atomic motion, leading to cooling and localization. In contrast to previous feedback experiments done with photon counting [2,3], feedback with heterodyne detection gives continuous information of the field leaking out of the cavity. In this talk we will present recent measurements that were enabled by this new feedback strategy. [1] A. Ourjoumtsev et al., Nature 474, 623 (2011). [2] A. Kubanek et al., Nature 462, 898 (2009). [3] M. Koch et al., Phys. Rev. Lett. 105, 173003 (2010).