Bose condensation in (random) traps

Abstract

We study a non-interacting (perfect) Bose-gas in random external potentials (traps). It is shown that a generalized Bose-Einstein condensation in the random eigenstates manifests if and only if the same occurs in the one-particle kinetic-energy eigenstates, which corresponds to the generalized condensation of the free Bose-gas. Moreover, we prove that the amounts of both condensate densities are equal. This statement is relevant for justification of the Bogoliubov approximation in the theory of disordered boson systems.