Berlin 2012 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 45: Correlated Electrons: Poster Session
TT 45.108: Poster
Donnerstag, 29. März 2012, 15:00–19:00, Poster B
Characterization of Mott-insulating and superfluid phases in the one-dimensional Bose-Hubbard model — •S. Ejima1, H. Fehske1, F. Gebhard2, K. zu Münster2, M. Knap3, E. Arrigoni3, and W. von den Linden3 — 1University Greifswald, Germany — 2University Marburg, Germany — 3TU Graz, Austria
We study the one-dimensional Bose-Hubbard model, the generic model for ultracold Bose gases, by means of various analytical and numerical techniques. Firstly, we determine the Kosterlitz-Thouless transition between the Mott insulator and the superfluid phase for the lowest two Mott lobes by analyzing the von Neumann entanglement entropy within a density matrix renormalization group (DMRG) approach. The phase boundaries are found to be in excellent agreement with those extracted from the scaling of the Luttinger liquid parameter. Secondly, we investigate the dynamical properties of the Bose-Hubberd model in both phases using analytical (strong-coupling expansion) and numerical (variational cluster approximation (VCA) and dynamical DMRG) methods. The results obtained for the single-particle photoemission spectra and the density of states agree very well in the strong-coupling regime. But even for intermediate couplings and within the superfluid phase, VCA reproduces the unbiased dynamical DMRG data surprisingly well, albeit the former one is based on a dynamical mean-field approach. Thirdly, including higher-order corrections in the strong coupling approach for the dynamical density-density correlation function, we discuss how the properties of the Mott insulator change in passing from the strong to the intermediate coupling regime.