Photon detectors in a double slit experiment

In summary, the double slit experiment with light has been done and has shown the wavelike nature of light, confirming the predictions of quantum theory. However, detecting a photon in the experiment destroys it, so techniques such as using polarizing waveplates and beamsplitters have been developed to detect the photon without destroying its coherence. Similar experiments have also been performed with more massive particles, such as buckyball molecules, demonstrating interference patterns and further supporting the wavelike nature of matter.
  • #1
Trollfaz
137
14
It is said that if one shoots photons in a double slit experiment, and place a detectors around the slits to find which slit the photon went, one will not see the photon interfere. However, to detect a photon, one must absorb it. So how does the photon detectors work by detecting the photons and still allowing it to reach the screen?
 
Physics news on Phys.org
  • #2
One thing you could do would be to put a transparent waveplate over one of the slits to rotate the polarization of light going through one slit 90 degrees while keeping the polarization of the other slit unaltered. Then, you can use polarizing beamsplitters at the detector to see which slit the light came from with each detection event. However, this sort of experiment would show no interference pattern because two light sources polarized at right angles to each other don't interfere. In general, any interaction with the photon that's strong enough to tell you which slit the photon passed through will also be strong enough to reduce the spatial coherence of the light to the point that the interference pattern is destroyed.

As an interesting side note, it is possible to detect the presence of a single photon without destroying it, but the previous argument holds. See for example:
https://www.laserfocusworld.com/articles/2013/11/nondestructive-photon-detection.html
 
  • Like
Likes PeroK and vanhees71
  • #3
I suspect that the double slit experiment is a thought experiment. I seriously doubt if anyone has ever done the experiment in reality. But I could be wrong. Has anyone ever done it? If so then where were the results published?
 
  • #4
Prophet said:
I suspect that the double slit experiment is a thought experiment. I seriously doubt if anyone has ever done the experiment in reality. But I could be wrong. Has anyone ever done it? If so then where were the results published?
I suspect you haven't even try to make a google search. I personally suspect it is one of the most repeated experiment because it does not implies very complicated apparatus.

They are up to using huge buckyball now.
 
  • Like
Likes phinds
  • #5
The double-slit experiment with light has been done already by Huygens and was taken as evidence for the wavelike nature of light early on. Today one can do this experiment with single photons and also with all kinds of massive particles and composite objects, as mentioned in the previous posting, even with the rather large C-60 buckyball molecules, all showing the wave-like aspects predicted by quantum theory.
 
  • #6
Prophet said:
I suspect that the double slit experiment is a thought experiment. I seriously doubt if anyone has ever done the experiment in reality. But I could be wrong. Has anyone ever done it? If so then where were the results published?
It's been done. https://arxiv.org/pdf/quant-ph/9903047.pdf uses a rather clever trick to get around the problem in the original post, namely that detecting a photon destroys it; there's a more user-friendly description here. And, although I don't have a link handy, the variant that @jfizzix describes have had been done many times.

That's specifically with photons, because that's what OP asked about. Nowadays, most experimental effort has gone into demonstrating interference with more massive particles, and there's no shortage of experimental results there. Google for "quantum buckyball interference" for some examples and further links.
 
Last edited:
  • #7
The experiment that most closely relates to what the OP asked is https://arxiv.org/abs/quant-ph/0402146, using C70 molecules instead of photons. By heating the molecules, one could get "which slit" info from emitted infrared photons, and that leads to a decrease of the interference fringes.
 
  • Like
Likes vanhees71

1. What is the purpose of using photon detectors in a double slit experiment?

Photon detectors are used in a double slit experiment to measure the intensity and position of the photons passing through the slits. This helps to determine the behavior of light, whether it behaves as a wave or a particle.

2. How do photon detectors work in a double slit experiment?

Photon detectors work by converting the energy of photons into an electrical signal. These signals are then amplified and recorded, providing data on the intensity and position of the photons passing through the slits.

3. What is the difference between using a single photon detector and multiple photon detectors in a double slit experiment?

A single photon detector records the intensity and position of one photon at a time, while multiple photon detectors can record the intensity and position of multiple photons simultaneously. This allows for more accurate measurements and analysis of the behavior of light.

4. Can photon detectors affect the outcome of a double slit experiment?

Yes, the act of detecting photons can impact their behavior and potentially alter the results of a double slit experiment. This is known as the observer effect and is a fundamental concept in quantum mechanics.

5. Are photon detectors necessary for a double slit experiment?

Photon detectors are not necessary for a double slit experiment, but they are useful for gathering data and analyzing the behavior of light. The experiment can still be conducted without photon detectors, but it may be more difficult to accurately measure and understand the results.

Similar threads

  • Quantum Physics
Replies
18
Views
1K
Replies
5
Views
780
  • Quantum Physics
2
Replies
36
Views
1K
  • Quantum Physics
Replies
9
Views
777
  • Quantum Physics
Replies
2
Views
280
  • Quantum Physics
Replies
14
Views
1K
Replies
32
Views
2K
  • Quantum Physics
2
Replies
49
Views
3K
Replies
19
Views
954
Replies
1
Views
640
Back
Top