Large-coordination-number expansion of a lattice Bose gas at finite temperature

Patrick Navez, Friedemann Queisser, and Ralf Schützhold
Phys. Rev. A 94, 023629 – Published 25 August 2016

Abstract

The expansion of the partition function for large coordination number Z is a long-standing method and has formerly been used to describe the Ising model at finite temperatures. We extend this approach and study the interacting Bose gas at finite temperatures. An analytical expression for the free energy is derived which is valid for weakly interacting and strongly interacting bosons. The transition line which separates the superfluid phase from Mott insulating or normal gas phase is shown for fillings n̂=1 and n̂=2. For unit filling, our findings agree qualitatively with quantum Monte Carlo results. Contrary to the well-known mean-field result, the shift of the critical temperature in the weakly interacting regime is apparent.

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  • Received 1 February 2016

DOI:https://doi.org/10.1103/PhysRevA.94.023629

©2016 American Physical Society

Physics Subject Headings (PhySH)

Atomic, Molecular & OpticalGeneral Physics

Authors & Affiliations

Patrick Navez1, Friedemann Queisser2,3, and Ralf Schützhold2

  • 1Department of Physics, University of Crete, P.O. Box 2208, Heraklion 71003, Greece
  • 2Fakultät für Physik, Universität Duisburg-Essen, Lotharstrasse 1, 47057 Duisburg, Germany
  • 3Department of Physics, University of British Columbia, Vancouver, V6T 1Z1, Canada

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Issue

Vol. 94, Iss. 2 — August 2016

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