Double slit experiment wave collapse

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SUMMARY

The discussion centers on the double slit experiment and the concept of wave function collapse in quantum mechanics, specifically regarding photons. Participants explore whether placing a second double slit behind a detector would allow a photon to regain its wave-like behavior after being detected. It is concluded that if a photon is detected, it ceases to exist for subsequent measurements, thus preventing any interference pattern from forming at a second detector. The conversation highlights the complexities of quantum measurement and the interpretations of wave function collapse.

PREREQUISITES
  • Understanding of quantum mechanics principles, particularly wave-particle duality.
  • Familiarity with the double slit experiment and its implications for quantum behavior.
  • Knowledge of quantum measurement theory and wave function collapse.
  • Basic grasp of quantum particle types, such as photons and electrons.
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  • Research the implications of quantum measurement on wave function collapse in quantum mechanics.
  • Explore various interpretations of quantum mechanics, such as Copenhagen and Many-Worlds interpretations.
  • Investigate advanced experiments involving quantum interference and detection methods.
  • Learn about synchrotron facilities and their role in generating coherent light sources for quantum experiments.
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Physicists, quantum mechanics students, and researchers interested in the foundational concepts of quantum theory and experimental physics.

Mkwglyg
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I would like to ask this question.
In the double slit experiment on wave particle duality of photon, we know that the wave function collapses and the photon behave like a particle whenever we peek.
Has anyone ever placed a second double slit behind the detector to see whether a particle regain its wave function ? Or the particle remains a particle ?
What i meant is this :
Single photon ... go through double slit... peek...wave collapse... we get clump on detector ... create a hole on detector... photon go through double slit again behind the detector.. this time no peek ... on the detector, do we get interference or clump ?
 
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Mkwglyg said:
I would like to ask this question.
In the double slit experiment on wave particle duality of photon, we know that the wave function collapses and the photon behave like a particle whenever we peek.
Has anyone ever placed a second double slit behind the detector to see whether a particle regain its wave function ? Or the particle remains a particle ?
What i meant is this :
Single photon ... go through double slit... peek...wave collapse... we get clump on detector ... create a hole on detector... photon go through double slit again behind the detector.. this time no peek ... on the detector, do we get interference or clump ?

I think you have a bit of a misunderstanding here.

When you are able to determine which-way the quantum particle (i.e. photon, electron, neutron, buckyball, etc.) goes through, then it is the superposition of paths that has been "collapsed", or determined. Then, the pattern on your screen will be the same pattern that you get with a single-slit diffraction.

If you add another set of double-slit AFTER that, then the original experiment remains intact, i.e. the quantum particle once again will have a superposition of paths UNTIL you make a determination which one it will go through. Then what I wrote above gets repeated.

Notice that in the whole setup, you know nothing about the source. All you care about is that quantum particle with identical properties are hitting your setup. Yet, I could have easily generated electrons or photons that came out of some interferometer, and I've selected the ones with the right, single frequency to send to your setup. In other words, your whole setup would be using something that came out of some interference setup already. And this will not be highly unusual, because we do this at synchrotron facilities all over the world. It is how we select the single frequency of light coming from undulators/wigglers placed in the synchrotron rings.

Zz.
 
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Mkwglyg said:
we know that the wave function collapses
No, we don't. In the basic math of QM, "collapse" just means we update our mathematical model when we know the result of a measurement. There is no claim that anything physically real corresponds to that mathematical update.

Different intepretations of QM make different claims about what is "actually happening" in a measurement; some say "collapse" is a real physical process, others do not. But discussion about what various interpretations say belongs in the QM interpretations subforum, not this one.

Mkwglyg said:
create a hole on detector
If the photon passes through a hole in the first detector, that means it doesn't get detected, so there is no "peek" and no "clump" at the first detector. If the photon is detected at the first detector, it ceases to exist (because it is absorbed by the detector), so the second detector will never detect anything.
 

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