Just to clarify (I'm pretty sure, but you seem knowledgeable), the quantum state is maintained when photons are absorbed/re-emitted by matter, right? Otherwise it seems like there would be a lot more vacuums involved. That was what I meant by 'the particular photons'; to my mind if you transmit your energy to an electron and are re-emitted you become a 'different' photon. It's a pretty silly point to argue about, though.