ABSTRACT
We have seen that the source domain of a transverse photon, a quantum physical object described in this book via the transverse part of the vector potential (AT (r, t)), may be identified with the transverse part of the charged-particle current density (JT (r, t)). In general, many-body quantum physics is needed to determine JT (r, t). However, it is possible to illustrate a number of important principles related to the characterization of the photon source domain by limiting oneself to a study of the single-particle (electron) current density concept in nonrelativistic quantum mechanics.
