Abstract
The validity of substituting a -number for the mode operator is established rigorously in full generality, thereby verifying one aspect of Bogoliubov's 1947 theory. This substitution not only yields the correct value of thermodynamic quantities such as the pressure or ground state energy, but also the value of that maximizes the partition function equals the true amount of condensation in the presence of a gauge-symmetry-breaking term. This point had previously been elusive.
- Received 16 December 2004
DOI:https://doi.org/10.1103/PhysRevLett.94.080401
©2005 American Physical Society