Consider this alternate form of the double-slit experiment:

 

Instead of one photon emitter firing single photons (one after the other) at two slits, suppose you had two photon emitters, one direct at each slit. In other words, the photons emitted by each one go directly to their corresponding slit, and only get the opportunity to interfere with the other after they've passed through the slits (and you have them setup to fire photons at exactly the same time).

 

What will happen?

 

1) Will an interference pattern emerge, just like in the single emitter case?

 

2) Assuming the answer to 1) is "yes", when the photon finally hits the screen and collapses into a point-like form, will there still be two of them, or will there be only one like in the single emitter case?

You'd get two photons on the screen, and an interference pattern if you did it repeatedly. This is topologically no different than two independent sources interfering.

OK, I just thought there might be an experiment to show that "reverse-superposition" could happen. It's just something I was wondering about. Reverse-superposition would be the case in which you start out with many particles and they converge into one (most likely in the regions where their waves cross). Is there any experiment that supports this? Any reasoning?

You can combine photons in nonlinear crystals; a common process is second-harmonic generation, though you can sum different frequencies as well.

 

 

http://en.wikipedia.org/wiki/Second_harmonic_generation

Can I just check I understand this correctly:

 

You have two single slit experiments, each with their own light source, brought close together. Then the single slit diffraction pattern, from each of the two single slits, will interfere and a "normal" double slit diffraction pattern will emerge?

Can I just check I understand this correctly:

 

You have two single slit experiments, each with their own light source, brought close together. Then the single slit diffraction pattern, from each of the two single slits, will interfere and a "normal" double slit diffraction pattern will emerge?

 

You should get interference of the overlapping beams. Toplogically this is no different than two sources placed side-by-side. As long as they are sufficiently coherent, you should see interference.

Ah yes, of course. It's obvious if you look at it from a graphical viewpoint.

 

 

Clearly an identical post-two-slit system can be obtained from two separate single slit diffractions. And then all you need is for those two waves to be in-phase and then you have something identical to the normal two slit experi.

 

Thanks!

please go to the link below

 

http://www.youtube.com/watch?v=H3_T6XCpRvA