- #36
Hydr0matic
- 197
- 1
I'm guessing equations 24/25? Why do you ask?ZapperZ said:BTW, based on Marcella's paper, where does it confirm your claim of what QM would produce using your scenario?
I'm guessing equations 24/25? Why do you ask?ZapperZ said:BTW, based on Marcella's paper, where does it confirm your claim of what QM would produce using your scenario?
Ok, I see your point now. And you are right, for some reason I was assuming that the non-slit distribution would be the equivalent of a totally constructive area. So I guess my original statement about the predictions of wave theory were incorrect. Thank you Cthugha for pointing this out so clearly.Cthugha said:As I said before: imagine an ideal detector behind a double slit. According to your theory, there won't be any redistributions of photons from areas of destructive interference towards areas of constructive interference. So in the areas of (pseudo) constructive interference there will be at most the number of counts, which would be there without the double slit, but no additional counts as the detector is already ideal and there is no redistribution. So in your theory constructive interference is just not there and does not have any effect.
Like I said, I'm not sure. I don't know enough about light-material interactions from a wave point of view to make a qualified guess. But if we assume that there's no perfect destructive interference anywhere, I would guess the waves would interact with the detector in some way, just not enough to actually register a detection.Cthugha said:What are you saying then? Reflected by what? Which wave theory describes such strange behaviour? Not even common classical wave theory does. What should happen to these photons?
This is my problem:Cthugha said:What is wrong with the Thorn paper?
The Thorn paper is not about interference, it's about how a beamsplitter works. And the whole experiment is set up to refute the idea that wave theory predicts a perfect 50/50 split, no matter how low-intensity light you use. Which I find quite ridiculous, unless you have a perfect source, a perfect beamsplitter and a perfect detector.J.J. Thorn et al paper said:Hence, if a single quantum of light is incident on the beamsplitter (BS), it should be detected at the transmission output or at the reflection output, but not both: there should be no coincident detections between the two outputs.
Tried to google but I don't know what to look for. Any brands or models you can recommend that's used for physics? Most have other applications, like photography and video.Cthugha said:However, you can try your idea at home. Building a double slit should not be much of a problem and some low cost photodiodes or a cheap CCD should not be too expensive as well.
Hydr0matic said:This is my problem: The Thorn paper is not about interference, it's about how a beamsplitter works. And the whole experiment is set up to refute the idea that wave theory predicts a perfect 50/50 split, no matter how low-intensity light you use. Which I find quite ridiculous, unless you have a perfect source, a perfect beamsplitter and a perfect detector.
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In this scenario, there is NO WAY that both R and T detectors go off simultaneously. In fact, a prerequisite of simultaneous detection, is that the source fires lightwaves with at least double the intensity of what the detector can detect. But ofcourse, if both detectors were to go off simultaneously, experimenters would assume that their source sent off 2 photons, and that would invalidate the experimental condition of a single-photon source.
So in my opinion, the setup is designed to have a detection at either R or T, never at both. And it doesn't matter if you go with wave theory or QM.
Hydr0matic said:But if you don't have perfect measuring devices, and you define the limit of what a detector can measure by 1 (i.e. a "photon"). And ..
1. We have a source that fires lightwaves with intensity 1 ± 0.5.
2. We have a beamsplitter that splits a wave 50/50 ± 25.
3. We have a detector that detects 1.25 ± 0.25.
Hydr0matic said:Tried to google but I don't know what to look for. Any brands or models you can recommend that's used for physics? Most have other applications, like photography and video.
There is a limitation on both intensity and wavelength.Cthugha said:Why is there a limit on what a detector can measure? If this limit is defined only by the incident intensity, this is already the qm picture of quantized excitations of the em-field.
Since blue light is closer to the electron wavelength it would require less intensity than the IR to set off the detector. So if both setups show identical results, that tells me that the blue source emits lightwaves with lower intensity than the IR source.Cthugha said:If you think, that the limit is just defined by some minimal transition energy of the detector, which needs to be overcome, you can easily test this by first using some single photon source in the IR range and afterwards some single photon source in the range of green or blue, where the energy of a single photon is roughly double the energy of an IR photon. If both setups show identical results, the limit is not defined by the minimum energy of the transition, but by the photon number.
Thanks!Cthugha said:I usually use stuff from Hamamatsu or ID Quantique, but I suppose, this stuff is clearly too expensive for doing experiments at home. I am pretty sure Thorlabs has some simple photodiodes in the 10-50€ range, but I suppose you will get just the photodiode and will have to worry about how to measure the photocurrent yourself. Are there any simple electronics markets near where you live? Most of them should at least have some basic diodes available.
Hydr0matic said:1. And measuring the splitted waves would not be the same as measuring the actual superposition.
You get dots because there is a limitation to how low-intensity light we actually can detect. What you would consider a photon, is what I would define as the lowest intensity light we're able to detect. I believe there is a non-uniform intensity distribution covering the detectors constantly, but simply too low-intensity to detect. So a detection by the CCD would in this scenario represent a higher-intensity-anomaly in the intensity distribution, and the source is filtered to such an extent that these events are so rare as to be considered "individual photons".
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2. This is my problem: The Thorn paper is not about interference, it's about how a beamsplitter works. And the whole experiment is set up to refute the idea that wave theory predicts a perfect 50/50 split, no matter how low-intensity light you use. Which I find quite ridiculous, unless you have a perfect source, a perfect beamsplitter and a perfect detector.
The OP question was not a general one about wave-particle duality. I simply stated that QM could not fully explain the double slit with light, nothing else.DrChinese said:The OP question is sort of like asking why linear accelerators are used to prove theories about particle physics rather than using a double slit setup. The answer is because the ones being used are the most effective - and convincing - way to test a specific scientific hypothesis.
That's what I was saying.DrChinese said:2. This represents a misunderstanding on your part, IMHO. The wave picture does not predict a *perfect* 50-50 split when low intensity light is used, simply that there is a transmitted T portion and a reflected R portion of the wave. It might be 60% T and 40% R for all we know.
Well THAT's interesting. Why don't you show me a paper with that setup. Add 4-5 levels of beamsplitters to the thorn setup and see if there's still a detection at some end. With only one beamsplitter, what does Thorn prove?DrChinese said:Let's assume that happened. Well, it turns out that only the 60% T one is detected and never the 40% R one. But how does it happen that our detectors magically only see the 60% one and not the 40% one? Is it because the 40% one is too low for our detector but the 60% one isn't? That fails too! We could add another beamsplitter in series - to further reduce the 60% intensity (which might now be 36% and 24% or something) - and see immediately that there is NO such lower threshold. 1 and only 1 photon is detected.
You just explained yourself how the Thorn paper is interpreted with waves, so which facts am I rejecting? And then you say that you would get the same result with more beamsplitters. Am I going to take your word on that?DrChinese said:You said reject the beamsplitter experiment because you don't agree with the "interpretation" of how a wave traverses it; but it comes across as a person who rejects facts that do not agree with your interpretation. So I ask: how do you explain Thorn? That should serve as a litmus test of your interpretation.
Hydr0matic said:An illustration of the setup:
http://physics.soderholms.com/doubleslit_setup.jpg [Broken]
Any thoughts?
Hydr0matic said:Well THAT's interesting. Why don't you show me a paper with that setup. Add 4-5 levels of beamsplitters to the thorn setup and see if there's still a detection at some end. With only one beamsplitter, what does Thorn prove?
My interpretation does not violate conservation of energy. There are no "new photons" as you call it. ALL light hits the detector, but if the light is interfering destructively at some point, it will not set off the detector. Instead it will continue it's propagation somewhere (not clear) and interact with something else.DrChinese said:Here is the detail about that... QM predicts that this increase will occur too - at that particular spot at least! And where do those "new" photons come from? They end up as reductions in the other spots they would otherwise have arrived at. The total detections, per QM, will remain constant. You cannot move from D to C and get more total detections. (Conservation of energy and all that.)
Well, there's nothing in your post that I didn't already know, so yes. I believe the detection rate will go up. I also believe that this test can be done in a much simpler way. All I need is a laser, a double slit, some cardboard and some standard light intensity meter. I place the light meter in the center constructive area at all time. I then change the destructive areas at the sides to constructive by moving them back. If QM is correct, I should see a decrease in intensity on my meter, as the photons are redistributed. It shouldn't matter if I shoot 1 photon at a time or a billion, the redistribution should still occur. Correct?DrChinese said:Assuming I was clear about the experimental setup, do you agree? Or do you still insist that the total photon count rate goes up?
All this tells me is that the detection limit is close to a 50% split, so that there is a small chance of a "non-detection" (ie exact 50/50 split). So if you remove the beamsplitter you would only get an insignificant increase in detections.DrChinese said:Well I guess some folks think the 377 standard deviations of the result put an end to the question. Keep in mind that they already split the beam in half and saw no significant change in the count rate. Most scientists would call that compelling.
Please do so, would appreciate that very much.DrChinese said:I have chatted with one of the authors of the Thorn paper previously, so I will ask if he has ever done that version of the experiment. It would be a nice way to put the icing on the cake, considering that this can be done in an undergrad setting. In effect, they could set a lower limit on the intensity of a probability wave at which it still acts as a discrete photon.
Hydr0matic said:Well, there's nothing in your post that I didn't already know, so yes. I believe the detection rate will go up. I also believe that this test can be done in a much simpler way. All I need is a laser, a double slit, some cardboard and some standard light intensity meter. I place the light meter in the center constructive area at all time. I then change the destructive areas at the sides to constructive by moving them back. If QM is correct, I should see a decrease in intensity on my meter, as the photons are redistributed. It shouldn't matter if I shoot 1 photon at a time or a billion, the redistribution should still occur. Correct?