Can both a photon and it's reflection hit a particle?

[Crazy Tosser]

So, if you have a mirror and a particle and the source emits one photon, which one hits the particle, the photon or it's reflection in the mirror or both?

 

[Doc Al]

If there's only one photon, how is there a reflection? (Ignoring for the moment the meaning of a "reflection" hitting something.)

 

[Crazy Tosser]

Well, the photon is a wave right? So if it can go through both slits at once, why can't it reflect from the mirror and hit the particle and directly hit the particle at the same time? Or if it can't, why does it go one way or the other way?

 

[jtbell]

Are you thinking of something like the Lloyd's mirror interference setup? The source and its image in the mirror act like the two slits in the usual two-slit interference setup. A single photon follows either one path or the other. If there is no "which-way" information, the two paths interfere and you build up an interference pattern on the screen as you send more and more photons through the system, one after the other.

 

[Crazy Tosser]

Are you thinking of something like the Lloyd's mirror interference setup? The source and its image in the mirror act like the two slits in the usual two-slit interference setup. A single photon follows either one path or the other. If there is no "which-way" information, the two paths interfere and you build up an interference pattern on the screen as you send more and more photons through the system, one after the other.

Yes that's exactly what I was thinking of, thank you very much. I didn't know there was an experiment for it.

 

[jtbell]

Most optics textbooks describe it, along with a variation called "Fresnel's mirrors" which uses two mirrors to produce two virtual sources that interfere. I don't know if anyone has done a one-photon-at-a-time version.