Okay, I’m looking this up, and it seems Dirac said that “Each photon then interferes only with itself; interference between two different photons never occurs”, saying this because, apparently, the amplitude gives the probability for a photon to be in a particular state, not the probability for a number of photons to be in a particular state.
I mean, given how a Bose-Einstein condensate works, it can’t possibly be true that, in general, bosons only interfere with their own identities, and not with other bosons of the same species.
Maybe each photon, even in a laser, tends to be distinguishable...? Or the case of a photon going one way or the other, factors out of the whole beam somehow, after you add up all the amplitudes...?
If I am out of my depth, let a physicist correct me. Even if it’s just to say, “You’re wrong.” Please.
PS: See also this arxiv paper. The introduction seems to be backing up the essential view described in this blog post, but saying that it’s difficult to get actual interference between two distinct photons for some reason...?
Okay, I’m looking this up, and it seems Dirac said that “Each photon then interferes only with itself; interference between two different photons never occurs”, saying this because, apparently, the amplitude gives the probability for a photon to be in a particular state, not the probability for a number of photons to be in a particular state.
It also seems that this statement is not to be interpreted in the intuitive way, because beams of light from two different lasers can interfere.
I know that there can be amplitudes for more than one particle being in a particular location.
I mean, given how a Bose-Einstein condensate works, it can’t possibly be true that, in general, bosons only interfere with their own identities, and not with other bosons of the same species.
Maybe each photon, even in a laser, tends to be distinguishable...? Or the case of a photon going one way or the other, factors out of the whole beam somehow, after you add up all the amplitudes...?
If I am out of my depth, let a physicist correct me. Even if it’s just to say, “You’re wrong.” Please.
PS: See also this arxiv paper. The introduction seems to be backing up the essential view described in this blog post, but saying that it’s difficult to get actual interference between two distinct photons for some reason...?
PPS: Dirac may have been talking about one particular experimental setup.
PPPS: Thanks, Mitchell.
PPPPS: This makes it clear what Dirac was saying.