Abstract
We consider a new way of going to the infinite volume thermodynamic limit for a finite density quantum system and apply it to the case of an ideal Boson gas. We describe two procedures for calculating the particle density in the thermodynamic limit, one local and one global, and show that they give different values for the density. Further calculations show that this discrepancy is caused by lack of macroscopic translation invariance of the system, which is not apparent at the microscopic level. We calculate the limiting value of the expectation function of the Weyl operators both above and below the critical density for Bose-Einstein condensation, and show that the condensate has paradoxical properties of a similar type to those recently discovered for the rotating Boson gas.
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Davies, E.B. The ideal Boson gas in an external scalar potential. Commun.Math. Phys. 30, 229–247 (1973). https://doi.org/10.1007/BF01837360
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DOI: https://doi.org/10.1007/BF01837360