Dresden 2011 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 57: Poster 3: Quantengase, Ultrakalte Atome, Ultrakalte Moleküle, Materiewellen Optik, Präzisionsmessungen, Metrologie

Q 57.36: Poster

Donnerstag, 17. März 2011, 16:30–19:30, P1

Effective occupation-dependent tunneling in optical lattices — •Maria Langbecker, Ole Jürgensen, Dirk-Sören Lühmann, and Klaus Sengstock — Institut für Laser-Physik, Universität Hamburg, 22761 Hamburg, Germany

Usually, atoms in optical lattices are described by single-band Hubbard models. The admixture of higher bands caused by interactions leads to non-negligible changes of the tunneling matrix elements. As a consequence the tunneling process becomes explicitly occupation-dependent which gives rise to an effective Hubbard Hamiltonian and novel exciting quantum phases.

We calculate the effective tunneling in optical lattices using a mean-field approach solely dependent on the occupation number of higher orbitals. This simple effective picture already gives results that compare well with the fully correlated treatment and visualizes intuitively the impact of higher-band tunneling processes. Even for few particles per lattice site, the effective tunneling differs notably from the single-band tunneling for both purely bosonic systems and boson-fermion mixtures.

The results demonstrate, in general, the important role of higher-band processes in optical lattices.