Interacting Bose-Fermi mixtures in optical lattices
Thorsten Best (Universität Mainz)

Bose-Fermi mixtures in periodic potentials, although scarce in nature, are interesting candidates for quantum simulation. They are expected to display a rich phase diagram, including exotic quantum states such as the so far elusive supersolid. The main control parameter in these systems is the strength of the interspecies interaction, which can be tuned all the way from strongly attractive to repulsive using a Feshbach resonance. I will present experiments demonstrating the interaction-induced modification of the onsite density distribution. As a consequence, both interaction energies and tunneling rates are significantly renormalized. While the former effect can be observed in quantum phase diffusion dynamics [1], the latter only manifests itself in a true many-body situation, such as the shift of the bosonic superfluid to Mott insulator transition observed recently [2]. A detailed understanding of these effects will be crucial for the preparation of complex many body quantum states in Bose-Fermi mixtures.

[1] M. Greiner et al., Nature 419, 51 (2002) [2] K. Günther et al., PRL 96, 180402 (2006), and S. Ospelkaus et al., PRL 96, 180403 (2006)