Angular Momentum of Photons
José A. Balseiro
The theory of elementary particles permits one to attribute well-defined angular momentum expressions to a given radiation field. A few simple examples are discussed, which involve systems of two photons, and of one atom and one photon, and which permit one to account for the conservation of total angular momentum. Conservation of total angular momentum, including radiation, is, however, of little practical importance, because spatial orientation of a given system requires, in general, the use of external magnetic fields, which perturb the angular momentum balance.
Physical Review•Jan 15, 1947•1 citation