  Coherent states are a well-established tool of quantum optics to describe
electromagnetic waves in terms of photons. However, they do not describe the
near-field regime of radiation sources. Instead, we generically use classical
solutions of Maxwell's equations to describe radiation in the near-field
regime. The classical solutions provide linear relations between currents and
emitted electromagnetic fields, whereas evolution of states at the quantum
level proceeds through unitary time evolution operators involving photon
operators. This begs questions how the classical radiation equations relate to
unitary quantum evolution, and how we can describe macroscopic fields from
antennas or magnetic coils in terms of elementary photons. The present paper
answers both questions through the construction of generalized Glauber states
for radiation emitters.
