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Q: Quantenoptik

Q 413: Quanteneffekte III

Q 413.2: Talk

Thursday, March 7, 2002, 14:15–14:30, HS 01/E02

Active feedback on a single atom — •P. Maunz, T. Fischer, T. Puppe, PWH. Pinkse, and G. Rempe — Max-Planck-Institut für Quantenoptik, 85748 Garching

The principle of feedback has been used to stabilise a variety of systems against perturbations from the environment. The application of feedback on the motion of a single neutral atom requires a position measurement with high spatial resolution and a large temporal bandwidth. This can be achieved using a high-finesse cavity.

In the experiment presented here the strong coupling between the atom and the light field leads to a dependence of the cavity transmittance on the position of the atom. The forces exerted by this light field [1] allow one to catch an atom by switching the intensity to a higher value when a strongly coupled atom is detected in the cavity [2].

This catching technique is now extended to continuous feedback, applied while the stored atom moves inside the cavity. By decreasing the light-intensity when the atom resides near the trap centre we suppress heating of the atom. Despite severe limitations from detection noise, the random character of the atomic motion and the shallow optical potential, the feedback extends the time the atom spends in the cavity.

[1] P. Münstermann, T. Fischer, P. Maunz, P.W.H. Pinkse, and G. Rempe, Phys. Rev. Lett. 82, 3791-3794 (1999).

[2] C.J. Hood, T.W. Lynn, A.C. Doherty, A.S. Parkins, and H.J. Kimble Science 287, 1447-1453 (2000); P.W.H. Pinkse, T. Fischer, P. Maunz, and G. Rempe, Nature 404, 365-368 (2000).