Darmstadt 2008 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 22: Quantengase (Gitter II)

Q 22.3: Talk

Tuesday, March 11, 2008, 17:00–17:15, 1C

Fermion induced long-range interaction in the Bose-Fermi-Hubbard model — •Alexander Mering and Michael Fleischhauer — Technische Universität Kaiserslautern

We present recent results on the Bose-Fermi-Hubbard model in the limit of fast (ultralight) fermions. In this case, the fermions act as virtual quanta giving rise to an effective long-range density-density interaction for the bosons. Starting from the full BFH Hamiltonian we adiabatically eliminate the fast fermions. It is important to include the mean field backaction of the bosons into the free dynamics of the fermions. This yields a renormalized long-range boson-boson interaction. The resulting bosonic Hamiltonian is studied analytically using a bosonization approach as well as numerically using the density-matrix-renormalization-group (DMRG). In particular the transition between a CDW-phase and a compressible phase with exponentially decaying bosonic correlations is studied analytically compared to DMRG results.