Stuttgart 2012 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 46: Quantengase: Optische Gitter 4

Q 46.7: Talk

Thursday, March 15, 2012, 15:30–15:45, V53.01

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

For the theoretical investigation of ultracold atoms in optical lattices, Hubbard models are frequently applied. These models are typically restricted to on-site interactions and the lowest single-particle orbital. We show that higher orbitals and off-site interactions can have a significant influence on optical lattice systems as indicated in recent experiments [1-3].

In particular, interactions of particles on neighboring sites, so-called bond-charge interactions, lead to an additional non-negligible tunneling. Within a fully correlated treatment, we perform a multi-orbital renormalization [4,5] to derive an extended Hubbard model.

Using this effective occupation-dependent Hubbard model, we compute the phase diagram of the superfluid to Mott-insulator transition for bosonic atoms and Bose-Fermi mixtures [4]. We find considerable deviations from the standard Hubbard model. The obtained results allow for new insight in the fundamental behavior of ultracold atoms in optical lattices beyond the commonly applied Hubbard model.

[1] T. Best et al., Phys. Rev. Lett. 102, 030408 (2009)

[2] S. Will et al., Nature (London) 465, 197 (2010)

[3] J. Heinze et al., Phys. Rev. Lett. 107, 135303 (2011)

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

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