Düsseldorf 2007 – scientific programme

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SYDP: Symposium Dissertationspreis

SYDP 1: Dissertationspreis Symposium

SYDP 1.4: Invited Talk

Tuesday, March 20, 2007, 12:00–12:30, 5D

Fermi-Bose mixtures with tunable interactions in 3D optical lattices — •S. Ospelkaus, C. Ospelkaus, O. Wille, M. Succo, L. Humbert, P. Ernst, K. Sengstock, and K. Bongs — Institut für Laser-Physik, Universität Hamburg

We present the first experimental realization of a Fermi-Bose quantum many-body system in a 3D optical lattice with bright perspectives for quantum simulation and strongly correlated phases. In these experiments, the effect of a small fermionic ⁴⁰K “impurity” fraction on the coherence properties of a bosonic ⁸⁷Rb sample is investigated and found to strongly affect the coherence properties of the bosonic cloud. The surprisingly large effect has triggered an intense discussion on possible explanations in terms of thermodynamic properties, mean field models and disorder-related localization scenarios.

Combining Feshbach-tunable interactions with 3-dimensional optical lattices, formation of heteronuclear Feshbach molecules in single wells of the lattice is demonstrated for the first time. Creation of molecules by means of rf association allows a precise determination of the molecular binding energy across the Feshbach resonance. Molecule formation in the optical lattice results in long lifetimes between 20 and 150 ms. The binding energy, lifetime and efficiency of rf association across the resonance can be understood in terms of a pseudopotential model developped together with F. Deuretzbacher, K. Plassmeier, F. Werner and D. Pfannkuche. We discuss current efforts towards the transfer of these Feshbach molecules into their internal ground state where they exhibit a permanent electric dipole moment.