Phase properties of some photon states with nonzero energy density

Abstract

We describe some photon states with nonzero energy density in the whole space; these states are obtained by taking a finite number of photons within a finite box and letting the volume and the number of photons go to infinity according to usual procedure in statistical mechanics. In such a limit we describe an observable phase operator; we investigate its properties both in the case of free field and in the case of coupling with prescribed classical sources. Finally we give a quantum description of uniform static field.