Darmstadt 2008 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 60: Quantengase (Gemische / Tunneleffekte)

Q 60.6: Talk

Friday, March 14, 2008, 12:15–12:30, 3G/H

Heteronuclear Feshbach molecules in an ultracold Bose-Fermi Mixture — •Carsten Klempt, Thorsten Henninger, Oliver Topic, Lisa Kattner, Eberhard Tiemann, Wolfgang Ertmer, and Jan Arlt — Institut für Quantenoptik, Leibniz Universität Hannover, Welfengarten 1, D-30167 Hannover, Germany

Within the past decade, quantum degenerate bosonic and fermionic ensembles were investigated in detail. The use of Feshbach resonances now allows for precise control of the interactions in heteronuclear mixtures of two atomic species. Within our experiments, bosonic ⁸⁷Rb atoms are used to cool an ensemble of fermionic ⁴⁰K atoms to joint quantum degeneracy. This mixture provides the starting point for the detailed analysis and manipulation of the interactions.

Applying a homogeneous magnetic field up to 700G allows for the investigation of heteronuclear Feshbach resonances in this mixture. The measurement of these resonances is of great interest for the precise investigation of the molecular potential. We have been able to observe 28 resonances in ten different spin combinations. Together with results from molecular spectroscopy, this allowed for a large improvement of the interaction model. One of the observed resonances is used for the production of weakly bound heteronuclear Feshbach molecules. The collisional stability of these molecules can be enhanced significantly by removing residual Rb atoms.

We report on the production of ultracold Feshbach molecules and the ongoing steps towards a deexcitation of such molecules into deeply bound molecular states via a Stimulated Raman Adiabatic Passage.