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Delayed Choice Quantum Eraser is a LIE 2017-08-18 12:10:18 Post No. 9111538
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Delayed Choice Quantum Eraser is a LIE 2017-08-18 12:10:18 Post No. 9111538
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pic related is the setup for the Delayed Choice Quantum Eraser experiment. The idea behind it is that when a photon is detected at D3 or D4, we can tell which slit it went through, but for any photons detected at D1 or D2 such is impossible to determine. The observation was that photons arriving at D3 and D4 had their entangled photons arriving at D0 form single clumps as the double-slit's interference pattern was destroyed, but those arriving at D1 and D2 formed series of bands which supposedly showed the re-emergence of superposition.
However, I found a problem with the basic premise:
>The information regarding which slit the photons arriving at D1/D2 is NOT LOST, we merely didn't set up the right sensors to detect it.
In order to get to the beam splitter BSc, photons must reflect off one of the two mirrors Ma or Mb. When they do that, they change momentum - and that momentum must be conserved somehow. It can only be transferred to the mirror itself, perhaps in a phonon. In any case, that change in momentum should be measurable with the right equipment - and if my understanding of quantum physics is correct, that makes it "observed" regardless of whether or not we actually set up the proper detector.
If we did, we'd be able to decompose the patterns constructed by our observations at D1 and D2 into components produced by photons which passed through each of the two slits. The aforementioned patterns are too complex to be formed by the combinations of two Gaussian distributions, and therefore...
>We can observe a so-called "interference" pattern being emitted by a single slit.
I'm not sure exactly what this implies, except that it seems to undermine the notion that our "Quantum Eraser" actually erases anything. More likely that something we haven't accounted for is generating an entirely new pattern. (I suspect a moire or interference pattern specific to the relationship between the laser source and/or prism, and beam splitter BSc.)
Or, am I just retarded?
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Here's the patterns photons made at D0 separated according to which detector (D1-D4) their entangled partner hit.
According to what I said earlier, the patterns of D1 and D2 must be decomposable into one part where the photons reflected off Ma, and another part where the photons reflected off Mb. And yet, there is no simple way to do so.
I suspect that the sum of the photons which reflected off Ma and hit D1 and those which reflected off Ma and hit D2 should correspond to the number of photons which hit D3 according to the transparency of BSa, but since this is quantum mechanics that could be totally wrong. Although if it didn't, that would probably be a groundbreaking discovery in and of itself.
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Think of the entire setup after the PS prism as a complicated double slit and screen.
'Which slit' info can be obtained anywhere between PS and BSc, like it can be obtained by adding detectors to the normal double slit experiment. One way would be making Ma and Mb momentum detectors but they chose to do it with BSa BSb D3 and D4. There's not really a difference.
Or 'which slit' info is by chance not gathered between PS and BSc and the superposition interference pattern is formed and detected after BSc D1 and D2 analogous to the traditional screen detector D0.
So you're right that sensors could be there at Ma and Mb but you miss the point that D3 and D4 do that same job, giving which slit info. When there's no detection before BSc the photon remains in a superposition of hitting both mirrors like going through both slits and that's what you see at D1 and D2.
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>>9111810
>One way would be making Ma and Mb momentum detectors but they chose to do it with BSa BSb D3 and D4. There's not really a difference.
With the beam splitters, must either arrive at D3/D4 OR at D1/D2. You can't measure both at once, which was the entire point of the experiment.
But you CAN get measurements both from Ma/Mb AND D1/D2 with the SAME PHOTON.
>So you're right that sensors could be there at Ma and Mb but you miss the point that D3 and D4 do that same job, giving which slit info.
But they destroy the photon in the process. Ma and Mb don't (or maybe they actually do but the new photons they make are still tied up in quantum weirdness).
>When there's no detection before BSc the photon remains in a superposition of hitting both mirrors like going through both slits and that's what you see at D1 and D2.
My point was that there IS ALWAYS detection before BSc in this setup. The mirror 'detects' the photon via momentum transfer, regardless of whether a human is paying attention to the mirror's momentum or not.
Unless you're arguing for some extreme consciousness-centric interpretation of quantum physics, to which I can only suggest we try the experiment with the changes I mentioned and see who's right.
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>>9112000
>CAN get measurements both from Ma/Mb AND D1/D2 with the SAME PHOTON
According to my understanding this is like saying you can get measurements from (a mirror at) slit1 or (a mirror at) slit2 and the screen in a more normal double slit+detectors setup. You can but then you have which path info so it's not a superposition and you see two bands instead of the interference pattern.
>mirror 'detects' the photon via momentum transfer
But so does the other mirror, both mirrors in superposition of reflected/not reflected a photon. You could check which mirror but if you did you wouldn't get interference at D1/D2.
>extreme consciousness-centric interpretation
Probably this, though I'd say it's more spooky than extreme. If detectors detected things the same way we do there wouldn't be correlation between what happens at D0 and the other Ds.
When you do the normal double slit experiment and get the interference pattern you can ask which slit the photon went through, but the existence of the interference pattern implies it's wrong to say it went through either, instead it went through both as a superposition, whatever that means.
Same here. Interference at D1/D2 implies the photons are a superposition of both possible paths and it's wrong to say they hit one mirror or the other.
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