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Q: Fachverband Quantenoptik und Photonik

Q 38: Quantengase: Gemische

Q 38.3: Vortrag

Mittwoch, 4. März 2009, 17:00–17:15, VMP 6 HS-A

Nonlinear corrections to the BFHM induced by higher Bloch band — •Alexander Mering and Michael Fleischhauer — Fachbereich Physik, Technische Universität Kaiserslautern, Germany

Experiments with ultracold atoms in deep lattices are mostly described theoretically by means of single band Hubbard-type Hamiltonians. For increasing interactions it is however necessary to take into account higher band effects. We present analytic calculations of the higher band corrections both of the hopping amplitudes J and the interaction amplitudes U and V for intra- and interspecies interaction in the Bose-Fermi-Hubbard Hamiltonian and derive nonlinear corrections to the hopping amplitudes mediated by the inter-species interaction. We adiabatically eliminate the higher bands by means of a second order perturbation theory using the exact solution of the dynamics in all higher bands. From these corrections the shift of the Mott insulator to superfluid transition caused by the coupling to the higher bands can be determined as a function of the filling and the interspecies scattering strength. Further simplification can be obtained by using harmonic oscillator approximation for the wannier functions yielding purely analytic results for the amplitudes J, U and V.