Do photons have spin angular momentum only if they are part of a circularly-polarized beam?
I suspect that every photon always has spin angular momentum, but in most cases they have a superposition of the two possible spin states, so the light seems linearly-polarized, except for the case of circularly-polarized light, where all photons express decoherence of the superposition, and they get the same spin state, which is either (+1) for all or (-1) for all.
Second question: two photons created together in such a way that they acquired quantum entanglement, are obliged to have a spin of the two states, but not their superposition? Does this mean they can't belong in a beam of linearly polarized light?
Thank you very much in advance.