Nonclassical states in optical communication to a remote receiver

The relation between the density operators of the aperture fields of a single-mode optical transmitter and a single-mode receiver is simply expressed in terms of their quasiprobability distributions. This formulation indicates that when the receiver is so far away that it picks up only a small fraction of the transmitted energy, the state induced in its aperture field by a nonclassical transmitted state differs only slightly from what it would be were a certain equivalent classical state transmitted instead. The implications for remote communications are discussed.