It is often described, that virtual photons are mere mathematical constructs, that can turn to real photons if there is enough time and space. And also, that virtual photons can mediate longitudinal field components of an E-field, especially from resting charges.
1.) Suppose a charge appears at the end of a rod like conductor by a shift of charges along the rod (let the charge rest at the end of the rod and not distribute over the rods surface). Suppose the rod is extremely long, so we don’t have to care about the counter-charge at the other end of the rod. From the moment of appearance, a longitudinal oriented front of an E-field will propagate from this charge with light speed (computable by retarded potentials). Will this front consist of real photons after some distance?
2.) Suppose the charge shift in the rod follows a sine movement. Then a longitudinal wave will propagate. Is there a possibility to slow down the speed of this propagation?
Wave propagation of real photons can be slowed down by dielectric material, superpositioning induced deflections of the oscillations of the materials electrons. But this requires a normal TEM-wave with orthogonal E- and B- components with respect to the propagation direction.
If real photons are given, slowing down a longitudinal wave could be done with superposition of some induced TE or TM waves? Real photons can be converted to phonons, excitons, polarons … - does this offer a possibility for a delaying superposition?