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DY: Fachverband Dynamik und Statistische Physik

DY 15: Controlling Dirty Bosons: Disorder Effects on BECs

DY 15.8: Talk

Tuesday, February 26, 2008, 16:15–16:30, MA 001

The Bose-Fermi-Hubbard model as a step to the disordered Bose-Hubbard-Model — •Alexander Mering and Michael Fleischhauer — Fachbereich Physik, Technische Universitaet Kaiserslautern

The influence of disorder on the ground-state phase diagram of the Bose-Hubbard model (BHM) is of long standing experimental and theoretical interest and yet not completely understood. We present analytical and numerical results for the Bose-Hubbard model with a binary disorder distribution resulting from the admixture of a heavy fermionic species as quasi-static impurities to the system. We find that for quenched and annealed disorder the phase diagram can be understood in terms of compressible, partial-compressible and incompressible phases. Numerical calculations using the density matrix renormalization group show that the partially compressible phases have a Bose-glass character. We also discuss the Bose-Fermi-Hubbard model in the limit of fast fermions where a finite lattice size leads to effects reminiscent of the BHM with a boxed disorder distribution.