Assume one photon of a momentum entangled pair of photons is absorbed by an isolated atom. Is there now an entanglement between the other photon and this atom? If so, in what way is the atom entangled with the photon? If the atom after a while emits a photon, under what conditions would the entanglement survive and get transferred to the emitted photon (i.e. that the photon would remain coherent)? I think this is the same question as to why would a photon travelling through glass or through air remain coherent (if it is absorbed and re-emitted). Now assume an entangled photon (of a pair of momemtum entangled photons) gets absorbed by an isolated ensemble of atoms bound together with many degrees of freedom. Does the entanglement survive? Does the entanglement get dissipated throughout the ensemble, but survives with intact total amplitude at the photon? Does it get attenuated? Or does the entanglement get completely broken/destroyed? Thanks to all.