Darmstadt 2008 – scientific programme

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A: Fachverband Atomphysik

A 19: Ultracold Rydberg gases (jointly with Q)

A 19.3: Talk

Thursday, March 13, 2008, 09:00–09:15, 2G

Many-particle mechanical effects of an interacting Rydberg gas — •Thomas Amthor, Markus Reetz-Lamour, Christian Giese, and Matthias Weidemüller — Physikalisches Institut, Universität Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg

Gases of ultracold Rydberg atoms have been found to spontaneously ionize and form plasmas [1]. Recent experiments showed that the initial ionization is mainly due to collisions induced by long-range forces between the cold Rydberg atoms. The acceleration and subsequent Penning ionization of Rydberg atoms has been investigated under different conditions, the underlying interactions being either of dipole-dipole [2] or van der Waals type [3]. For attractive interaction potentials, atoms excited to Rydberg states on the red-detuned wing of the resonance are observed to ionize first, as more atom pairs are prepared at short distances and experience strong attractive forces. Here we discuss the ionization dynamics of gases initially prepared in states with purely repulsive interaction. This requires a more detailed model including many-particle aspects and mechanisms for state redistribution to overcome the repulsive forces. A Monte Carlo model for the description of such a system is presented and agrees well with experimental observations [4].

[1] M. P. Robinson et al., Phys. Rev. Lett. 85, 4466 (2000)

[2] W. Li et al., Phys. Rev. Lett. 94, 173001 (2005)

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

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