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I read about a double slit experiment where the detector clicks when a photon goes through the slit. When the detector doesn't click, it means the photon must have gone through the other slit, and a particle pattern still forms. I can't find the experiment that's being referred too though. Does anyone know how I can find it?

Qmechanic
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Jen Sanchez
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  • Do you mean "Double slit experiment for one photon at a time"? – sslucifer Oct 25 '21 at 22:37
  • yes, and a detector on one slit. A detector that clicks if a photon passes. – Jen Sanchez Oct 26 '21 at 19:02
  • @JenSanchez If a detector detects a photon than the photon must have been absorbed by the detective. A photon cannot pass the slit and be detected at the slit. As for the experiment, just go to YouTube and type double slit experiment one photon at a time. – Bill Alsept Oct 27 '21 at 01:02
  • I mean and experiment where there's a detector on one slit (say slit B). Photons are coming one at a time. If the detector fails to click, we know it must have gone through the other slit (slit A), and it acts like a particle. I read about it recently, but there wasn't a reference. – Jen Sanchez Oct 27 '21 at 03:36
  • Don't go out of your' way. If It was done as described, i'll find it. I've found a few refrences to it. The idea that the knowledge of which slit, even without interaction, could change the results blows my mind. – Jen Sanchez Oct 27 '21 at 03:40
  • @JenSanchez The idea that knowledge can change the results is misleading. You’re still dealing with individual photons that went through one slit or the other if they made it to the detection screen. – Bill Alsept Oct 27 '21 at 14:58
  • Information changes the result (and by extention knowledge, or what we can know does). It's not misleadng,it's fact, and I can quote some of the most brilliant minds in physics to back me up. If, in this experiment, a photon doesn't go through the slit w/ a detector, it must have gone through the other. Then it would act like a particle with no interaction whatsoever. I think it's called negative measurement, and i've seen it with other experiments. I don't like this biased site. – Jen Sanchez Oct 28 '21 at 19:40

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This was a thought experiment .... it is impossible for a photon to produce a click and then carry on to the screen. If a photon makes a click it is detected and that's the end of the photon. For electrons an actual experiment was done using light to detect which slit ... and this caused the electrons to stop making the pattern.

Also you can read this answer for more insight: How does the double slit experiment ensure phase coherence?

PhysicsDave
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  • I found an experiment that's pretty close to what I was looking for. I'm imagining photon going to two slits, with a detector at one slit. When the photon goes to the slit without a detector, it still produces a particle pattern. The wave would have to know the detector is there, and without setting it off, go through the other slit. Physics is trippy. Thank you! I'm learning. – Jen Sanchez Nov 07 '21 at 06:00
  • Here is a paper that sort of measured which slit for photons, it uses "weak" measurement. https://www.physics.utoronto.ca/~aephraim/PWMar13steinberg-final.pdf. – PhysicsDave Nov 08 '21 at 17:29
  • If we are using photons you can not use a detector for which path. If you put a detector on one slit than that slit is blocked! if you put it over half the slit then a portion of the photons will get blocked and some will get by to make the interference pattern. – PhysicsDave Nov 08 '21 at 17:33
  • Every photon figures out a path .... the path is constantly changing as objects move about .... it is all due to the EM field, virtual photons and real ones. Example .. a photon leaves a star and travels for a million years, gets to earth and then a scientist places a mirror in front and sends it all the way back to the star! The photon reacts at the speed of light, figuring out its new path ..... – PhysicsDave Nov 08 '21 at 17:38
  • the DSE has been mysterious for over a hundred years. A lot of the bad science and confusion comes from being forced to think in classical terms .... like photons interfered and cancelled (violation of energy). Feynman and Dirac figured out that each photon must figure out its own path which is true ... but they were unable to say how. They could have spent more time on it if it was truly important but the nuclear age was dawning and the photons behaviour was well enough understood for their purposes. – PhysicsDave Nov 08 '21 at 17:49
  • I have seen it discussed here and there that a path can be determined by virtual forces (V photons) as well as real ones. For example an excited electon/atom is already generated forces in the environment ... much before the real photon has begun to transmit. My advice (if you want it) is not to waste too much time on this DSE mystery, which is really not a mystery ... so much old classical thinking has made it a mystery. Nuclear physics and quantum optics are better to learn about ... but be careful some old classical ideas creep into these areas a s well. – PhysicsDave Nov 08 '21 at 17:58
  • Thank you, I didn't know about the photon being absorbed. I think there are some newer detectors that don't absorb the whole photon. I found an experiment that is like I described using a photo-plate (still learning what that is). – Jen Sanchez Nov 09 '21 at 23:22
  • I actually love the mysteries, and I like Max Plank alot. I think he's right about alot of things, but I don't know that most physicist will ever accept that. – Jen Sanchez Nov 09 '21 at 23:30
  • All physicists accept Plank theory on UV light and quantization ... I've never heard any disagreement. Xrays can leave a mark on a photographic plate and still travel on to affect another plate .... BUT the original X-ray has changed .... and it most likely that the original xray was completely absorbed and the exiting X-ray which is of lower energy was newly created. On YouTube you can find "Dr Physics A" and all the videos will teach you much about physics ..... – PhysicsDave Nov 11 '21 at 21:49