| We consider the large N limit of interacting Bose gases using path integral methods. This way of including the quantum fluctuations gives a consistent extension of Bogoliubov theory for finite temperatures. Our study is also applied to the Bose-Hubbard model. In this case we study how the spectrum of the insulating phase interpolates with the one of the superfluid phase. This is an aspect of the Bose-Hubbard model that remained elusive. |
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