Dresden 2011 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 31: Quantum Gases: Opt. Lattice 2

Q 31.4: Vortrag

Mittwoch, 16. März 2011, 15:15–15:30, HSZ 02

Occupation-dependent multi-band Hubbard models — •Ole Jürgensen, Dirk-Sören Lühmann, and Klaus Sengstock — Institut für Laser-Physik, Universität Hamburg, 22761 Hamburg, Germany

Typically, tunneling and interactions are competing processes in optical lattices, where the quantum phase transition to the Mott insulator is one of the most prominent examples. So far, often single band Bose-Hubbard models are used to study these systems theoretically. Recently it was pointed out that already for moderate parameters the interaction promotes particles to higher bands of the lattice which alters the energy gain connected with the tunneling significantly[1,2]. In bosonic systems, new quantum phases have been predicted for occupation-dependent tunneling.

Using a fully correlated treatment, we calculate the effective tunneling and on-site interactions in optical lattices for bosonic atoms and Bose-Fermi mixtures. The renormalized tunneling sums over all combinations of higher-band processes and shows substantial deviations from the uncorrelated tunneling. We introduce an occupation-dependent Hubbard model which effectively covers the role of higher-orbital physics.

The results obtained from our fully correlated calculation cast new light on the underlying processes and support the significance of occupation-dependent Hubbard models.

[1] D.-S. Lühmann et al., Phys. Rev. Lett. 101, 050402 (2008)

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