Düsseldorf 2007 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 24: Quantengase (Bosonische Gitter II)

Q 24.7: Talk

Tuesday, March 20, 2007, 15:30–15:45, 6J

Ultracold Gases in 1D Optical Lattices: Exact Diagonalisation vs. Perturbation Theory — •Felix Schmitt, Markus Hild, Ilona Tuerschmann, and Robert Roth — Institut fuer Kernphysik, Technische Universitaet Darmstadt

We discuss several approaches to treat ultracold atomic gases in inhomogeneous 1D optical lattices within the Bose-Hubbard framework. Exact diagonalisation techniques, as one of these approaches, suffer from the restriction in system size due to the factorial growth of the many-particle basis. Employing a physically motivated adaptive basis truncation scheme we can reduce the basis size by more than two orders of magnitude without significant errors in all accessible observables. Moreover, a straightforward perturbative method is used to extend the system size further. Our aim is to reach experimentally relevant system sizes, to study inhomogeneous lattice topologies, and to investigate finite-size effects.