Feynman Double-Slit: 2nd Slit Effects Explored

[decoherent]

If you fire electrons, one after the other, at a double-slit, and let them hit a wall, you get light and dark bands.

If you shine a light on the electrons as they pass through the double-slit to find out which of the paths they took, there's no interference pattern, just two piles.

That's the Feynman double-slit.

Now...

What happens if, after you shine the light, you force them through ANOTHER double-slit?

Does the distance between the 1st double-slit and 2nd double-slit matter?

 

[DrClaude]

What happens if, after you shine the light, you force them through ANOTHER double-slit?

It is as if two sources were used in the original experiment.

Does the distance between the 1st double-slit and 2nd double-slit matter?

Yes. For an interference pattern to appear, the two sets of slits must be far enough apart such that particles coming from both of the first pair of slits can reach either of the second pair of slits.