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Q: Fachverband Quantenoptik und Photonik

Q 22: Ultrakalte Plasmen und Rydberg-Gase (gemeinsam mit A)

Q 22.2: Fachvortrag

Dienstag, 20. März 2007, 11:00–11:30, 5M

Rydberg excitation in the strong blockade regime: from thermal cloud to BEC — •Vera Bendkowsky1, Rolf Heidemann1, Ulrich Raitzsch1, Björn Butscher1, Helmar Bender1, Robert Löw1, Luis Santos2, and Tilman Pfau115. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart — 2Institut für Theoretische Physik, Universität Hannover, Appelstraße 2, 30167 Hannover

The van der Waals interaction of Rydberg atoms can - depending on the atomic density and the excitation strength - lead to a supression of Rydberg excitation in a cloud of ground state atoms. In this blockade regime the atomic sample can be considered as consisting of many blockade spheres with N ground state atoms within a sphere but only one excited Rydberg atom.

In our experiments we excite magnetically trapped Rubidium atoms at temperatures between a few µK and BEC to the 43S state. In the thermal cloud we observe saturation in the Rydberg excitation for a large range of densities and Rabi frequencies Ω0. As expected for coherent collective excitation of any mesoscopic system the initial excitation rate is proportional to √NΩ0. The scaling of the saturation value is investigated with respect to N and Ω0.

Furthermore we present first results on Rydberg excitation in a BEC. The measurements show a clear signature of Rydberg excitation within the BEC. The results are compared with a mean field calculation for the quantum dynamics above and below Tc.


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DPG-Physik > DPG-Verhandlungen > 2007 > Düsseldorf