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 57.19: Poster

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

Bosons and fermions in three-dimensional optical lattices: Multi-band and nonlinear hopping corrections — •Alexander Mering and Michael Fleischhauer — Fachbereich Physik and research center OPTIMAS, Technische Universität Kaiserslautern

Recent experiments revealed the importance of higher-band effects for the Mott insulator – superfluid transition of ultracold bosonic atoms or mixtures of bosons and fermions in deep optical lattices [Best et al., PRL 102, 030408 (2009); Will et al., Nature 465, 197 (2010)]. In the present work, we derive an effective lowest-band Hamiltonian in 3D that generalizes the standard Bose-Fermi Hubbard model taking these effects into account within an adiabatic elimination scheme of virtual transitions to higher bands. Nonlinear corrections of the tunneling amplitudes mediated by interspecies interactions being neglected so far are shown to be of equal importance. Further more, a correct description of the lattice states in terms of the bare-lattice Wannier functions turns out to be essential in contrast to approximations such as harmonic oscillator states. Especially for repulsive interactions, our approach reveals the importance of the interplay between nonlinear and higher-band corrections for the understanding of the observed shift of the MI-SF transition.