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D. B. M. Dickerscheid, D. van Oosten, P. J. H. Denteneer and H. T. C. Stoof, “Ultracold Atoms in Optical Lattices,” Physical Review A, Vol. 68, No. 4, 2003, Article ID: 043623. doi:10.1103/PhysRevA.68.043623

has been cited by the following article:

• TITLE: Green’s Function Approach to the Bose-Hubbard Model

  AUTHORS: Matthias Ohliger, Axel Pelster

  KEYWORDS: Bose-Hubbard Model; Quantum Phase Transition; Phase Boundary

  JOURNAL NAME: World Journal of Condensed Matter Physics, Vol.3 No.2, May 24, 2013

  ABSTRACT: We use a diagrammatic hopping expansion to calculate finite-temperature Green functions of the Bose-Hubbard model which describes bosons in an optical lattice. This technique allows for a summation of subsets of diagrams, so the divergence of the Green function leads to non-perturbative results for the boundary between the superfluid and the Mott phase for finite temperatures. Whereas the first-order calculation reproduces the seminal mean-field result, the second order goes beyond and shifts the phase boundary in the immediate vicinity of the critical parameters determined by high-precision Monte-Carlo simulations of the Bose-Hubbard model. In addition, our Green’s function approach allows for calculating the excitation spectrum both for zero and finite temperature and for determining the effective masses of particles and holes.