By virtue of the consideration of polarization and phase properties of dipole radiation in the quantum domain, it is shown that the concept of free electromagnetic field should be considered as a quite risky approximation in the description of quantum fluctuations of some physical observables.
SHUMOVSKY, ALEXANDER and MÜSTECAPLIOĞLU, ÖZGÜR (1999) "The concept of free electromagnetic field in quantum domain," Turkish Journal of Physics: Vol. 23: No. 5, Article 3. Available at: https://journals.tubitak.gov.tr/physics/vol23/iss5/3