Hamburg 2009 – scientific programme

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A: Fachverband Atomphysik

A 19: Ultracold atoms III: Manipulation and detection / Rydbergatoms (with Q)

A 19.7: Talk

Wednesday, March 4, 2009, 18:00–18:15, Audi-B

Controlling the pair distribution in an ultracold Rydberg gas — •Christoph S. Hofmann, Thomas Amthor, Christian Giese, Hanna Schempp, Brett DePaola, and Matthias Weidemüller — Physikalisches Institut, Universität Heidelberg, Philosophenweg 12, 69120 Heidelberg

We show that the pair distribution in an ultracold Rydberg gas can be influenced by means of red or blue detuned Rydberg excitations. To demonstrate this the ionization of the Rydberg gas is used as a sensitive probe [1,2]: For attractive interaction potentials, atoms excited to Rydberg states on the red-detuned wing of the resonance are observed to ionize first, since more atom pairs are prepared at small interatomic distances and hence experience strong attractive forces. This excitation scheme is extended by using Autler-Townes-splittings of up to 150 MHz in order to exploit a wider frequency range for the pair distribution control. This allows to address pairs with a 1.6 times smaller pair distance, yielding an increase of the interaction strength by more than one order of magnitude. A Monte Carlo model for the description of such a system is presented and agrees well with experimental observations. The Autler-Townes-splitting moreover allows for rapid frequency chirps across a resonance without actually tuning any of the excitation laser frequencies.

[1] T. Amthor et al., Phys. Rev. Lett. 98, 023004 (2007)

[2] T. Amthor et al., Phys. Rev. A 76, 054702 (2007)