Stuttgart 2012 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 35: Poster 2

Q 35.10: Poster

Wednesday, March 14, 2012, 16:30–19:00, Poster.I+II

Renormalization of Hubbard models for optical lattices — •Ole Jürgensen, Dirk-Sören Lühmann, and Klaus Sengstock — Institut für Laser-Physik, Universität Hamburg

Ultracold atoms in optical lattices are often described by means of single-band Hubbard models that are restricted to on-site interactions. Off-site interactions lead to an additional tunneling process, so-called bond-charge interactions that can be identified with an effective tunneling potential.

We apply a fully correlated treatment to derive an extended model that includes off-site interactions, as well as higher-orbital processes [1,2]. The effective tunneling in optical lattices is found to deviate significantly from the commonly applied Hubbard models.

Using this model, we analyse the superfluid to Mott-insulator transition for a purely bosonic system as well as for Bose-Fermi mixtures. The corresponding phase diagrams are strongly influenced by the above extensions, which corresponds to a considerable shift of the critical lattice depth of the transition.

The presented results cast new light on the importance of higher bands and off-site interactions for ultracold atoms in optical lattices.

[1] D.-S. Lühmann et al., arxiv: 1108.3013

[2] U. Bissbort et al., arxiv: 1108.6047