1 Electron, 2 Slits, and the Rest of the Pattern

In summary, the two-slit experiment involves sending multiple particles, such as electrons or photons, through two slits one at a time to create an interference pattern over time. This is explained by the particles behaving as waves and interfering with themselves as they pass through the slits. However, it is puzzling how we can observe multiple bands of constructive and destructive interference when shooting particles one at a time, as this would require the particles to interfere with themselves and with the waves behind them. Various theories and explanations have been proposed to understand this phenomenon.
  • #1
Meta.Joe
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In the two-slit experiment, as I understand it, an interference pattern can be generated by sending many electrons (or photons) through the two slits one at a time, and the pattern itself gets built up over time. The explanation is usually this: A single electron travels as a wave and so interferes with itself as it passes through the two slits, and the interference pattern results from multiple electrons interfering with themselves as they pass through the two slits. My question is this: If a single wave were to pass through the two slits and interfere with itself, isn't the middle of the detector screen the only place you get constructive interference? If so, then multiple electrons, shot one at a time, should generate a pattern that exhibits constructive interference only in the middle of the screen. So, what explains the other cases of constructive interference observed across the detector screen?
 
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  • #2
Meta.Joe said:
My question is this: If a single wave were to pass through the two slits and interfere with itself, isn't the middle of the detector screen the only place you get constructive interference? If so, then multiple electrons, shot one at a time, should generate a pattern that exhibits constructive interference only in the middle of the screen. So, what explains the other cases of constructive interference observed across the detector screen?

Welcome to PhysicsForums, Meta.Joe!

There are areas of both constructive and destructive interference. They do not form the pattern you describe. If there were no interference, you would see 2 bars. With interference, there are alternating bands of constructive/destructive interference and some particles will end up far from the middle area.

http://dev.physicslab.org/asp/applets/doubleslit/default.asp

http://en.wikipedia.org/wiki/Photon_dynamics_in_the_double-slit_experiment
 
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  • #3
Thanks, Dr. Chinese! I'm glad to have discovered the forum. My question was a little unclear. I should have asked, Why don't we get the pattern that I describe, specifically when we shoot only one electron at a time through the two slits? What is puzzling me is that the multiple bands of constructive (and destructive) interference seem to require one wave's interfering both with itself and with the waves behind it. But since we are shooting only one electron at a time, there are no waves behind the electron for it to interfere with. So the the interference pattern should (it seems to me) be that of just one wave interfering with itself, which (I think) would give the pattern I have described. I just don't understand why we don't get the pattern I have described (rather than the pattern we do get) when shooting electrons one at a time. Does that make sense?
 
  • #4
Meta.Joe said:
Thanks, Dr. Chinese! I'm glad to have discovered the forum. My question was a little unclear. I should have asked, Why don't we get the pattern that I describe, specifically when we shoot only one electron at a time through the two slits? What is puzzling me is that the multiple bands of constructive (and destructive) interference seem to require one wave's interfering both with itself and with the waves behind it. But since we are shooting only one electron at a time, there are no waves behind the electron for it to interfere with. So the the interference pattern should (it seems to me) be that of just one wave interfering with itself, which (I think) would give the pattern I have described. I just don't understand why we don't get the pattern I have described (rather than the pattern we do get) when shooting electrons one at a time. Does that make sense?

Well, a bit difficult to answer more deeply other than to say: add the 2 waves where they overlap on the screen and that is the pattern you get. This may help:

http://www.hitachi.com/rd/research/em/doubleslit.html

Here is a very technical treatment:

http://arxiv.org/ftp/quant-ph/papers/0703/0703126.pdf
 
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  • #5
Thanks! Technical indeed. It does seem, though, that we can get a multi-band interference pattern from just two waves interacting. Thanks again.
 
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What is the "1 Electron, 2 Slits, and the Rest of the Pattern" experiment?

The "1 Electron, 2 Slits, and the Rest of the Pattern" experiment is a thought experiment that demonstrates the wave-particle duality of electrons. It involves firing a single electron at a barrier with two slits and observing the resulting interference pattern on a screen behind the barrier.

What is wave-particle duality?

Wave-particle duality is the concept that particles such as electrons can exhibit both wave-like and particle-like behaviors. This means they can act as both waves and particles depending on the experimental setup.

What is the significance of the "1 Electron, 2 Slits, and the Rest of the Pattern" experiment?

The significance of this experiment is that it supports the theory of quantum mechanics, which states that particles can behave as both waves and particles. It also challenges our understanding of classical physics, as it shows that particles can exhibit behaviors that are not intuitive based on our everyday experiences.

How does the experiment demonstrate wave-particle duality?

When the electron is fired at the barrier with two slits, it can pass through both slits simultaneously and interfere with itself, creating an interference pattern on the screen behind the barrier. This behavior is characteristic of waves. However, when the electron is observed, it behaves like a particle, only passing through one of the slits and creating a single spot on the screen. This dual behavior demonstrates the wave-particle duality of electrons.

What are the practical applications of the "1 Electron, 2 Slits, and the Rest of the Pattern" experiment?

The experiment has practical applications in fields such as quantum computing and cryptography, as well as in the study of fundamental particles and their behavior. It also plays a significant role in the development of quantum mechanics and our understanding of the nature of matter.

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