Interference Patterns & Photon Paths: Exploring the Double Slit Experiment

In summary, the conversation discusses the behavior of photons in a double slit experiment and how interference patterns can still occur even when photons travel through different paths. The question is raised about the effect of a path cutting device on the interference pattern and whether the path should be clear at the moment of emission or when reaching the blocker. The response explains that interference can still occur as long as the coherence length of the photon is not exceeded, and the rotating wheel does not change this principle. The author also notes that in the video, the longer path is likely still within the coherence time of the photons, so there is no mistake in the experiment.
  • #1
deadbeef
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TL;DR Summary
Question regarding photon taking longer and short path and interfering with spinnig disc that can block photon path at different moments
Hi.
As i understand in double slit experiment photon can arrive at slits through different paths (longer and shorter) and it would still show interference pattern.
My question is - if there was some path cutting device in a way of photon (on longest path after length that photon arrive at detector) (device like rotating wheel with holes) how would that affect interference pattern? Should path be clear at moment when photon is emitted? Or at moment when calculated distance to blocker (even if after detector) matches time to take longest path to blocker?

Thank you,
Reinis
 
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  • #2
deadbeef said:
As i understand in double slit experiment photon can arrive at slits through different paths (longer and shorter) and it would still show interference pattern.
Yes, as long as the difference in length doesn’t exceed the coherence length of the photon so that arrival at the same point on the screen at the same time is possible through either path. Increase the path length beyond that and there will be no interference. Behavior like this is why we can’t think of the photon as a small solid object following some trajectory through space.

The rotating wheel doesn’t change the general principle: if there are open paths through both slits we’ll get some amount of interference between them.
 
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  • #3
Nugatory said:
Yes, as long as the difference in length doesn’t exceed the coherence length of the photon
According to author (in video) he is observing interference when one path is considerably longer that other path. Is there some error in his experiment?
 
  • #4
deadbeef said:
According to author (in video) he is observing interference when one path is considerably longer that other path. Is there some error in his experiment?
I haven’t watched the whole thing, just the few seconds you excerpted…. But from that I would expect that “considerably longer” is still less than the coherence time of the photons, so no mistake.
 
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1. What is the double slit experiment?

The double slit experiment is a classic physics experiment that demonstrates the wave-particle duality of light. It involves shining a beam of light through two parallel slits and observing the resulting interference pattern on a screen.

2. Why is the double slit experiment important?

The double slit experiment is important because it provided evidence for the wave-like behavior of light, which was crucial in the development of quantum mechanics. It also raises questions about the nature of reality and the role of observation in shaping it.

3. How does the double slit experiment demonstrate interference patterns?

When light passes through the two slits, it creates two coherent sources of light waves. These waves interfere with each other and create a pattern of bright and dark fringes on the screen, known as an interference pattern.

4. What are photon paths in the double slit experiment?

Photon paths refer to the paths that individual photons (particles of light) take as they pass through the double slits and create the interference pattern. These paths are not predictable and can only be observed through the resulting interference pattern.

5. Can the double slit experiment be performed with other particles besides light?

Yes, the double slit experiment has been performed with other particles such as electrons, protons, and even large molecules. This further supports the wave-particle duality of matter and the fundamental principles of quantum mechanics.

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