Calculations of QM prediction of -a.b

Foundations of physics and/or philosophy of physics, and in particular, posts on unresolved or controversial issues

Re: Calculations of QM prediction of -a.b

Postby gill1109 » Wed Nov 25, 2020 1:02 am

FrediFizzx wrote:Blah, Blah, Blah! Let's see your freakin' calculation to make the standard QM calculation non-local. Put up or shut up!

This thread is about calculations. Everyone, show your math or just shut the f... up!
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QM calculations in 3D space are done by Igor Volovich in https://arxiv.org/abs/quant-ph/0012010 , https://arxiv.org/pdf/quant-ph/0012010.pdf . He actually shows that the wave functions will be so spread out that there will be an unavoidable detector-inefficiency, so large that a loophole-free experiment is impossible. I think this needs to be redone with essentially 1D propagation of the wave packages. I would be surprised if no-one has done it before. The guys in quantum optics who do the experiments have surely worked through this, before. I am asking a few. Here’s a first question-answer pair. No calculation yet, Fred, sorry. You should be able to do such a calculation better than me! I’m a statistician, not a physicist.

RDG. Q: I suppose that if two photons leave a source in a Bell state of polarisation, then each of them will have experienced a unitary transformation of state due to time of travel before they reach a detector. The paths are not equally long, either. So when they reach the detectors, the directions in which they should be measured to get a Bell violation need to be discovered anew by some calibration process. Ie you won’t see the negative cosine (or whatever) but a shifted cosine. In good experiments the hard work is keeping the shift constant, as time goes by, and things warm up, vibrate, or whatever.

Expert. A: From what I know the story is correct. There are often several variations, day-night for example, but depending on setup the variation can be fast. One experiment I saw had the optical fibre spun along a powerline that was suspended in air, this is a common setup over long distances. Then there was a 100Hz period too, probably from vibrations induced from the powerline frequency 50 Hz. Stabilization can be hard.
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Re: Calculations of QM prediction of -a.b

Postby gill1109 » Wed Nov 25, 2020 3:29 am

Now I have some more answers from another expert.

Expert 2: It’s substantially wrong [he means: RDG’s guess is wrong]. A polarisation-entangled state is, for example, HV-VH. Polarisation is preserved during propagation. H means horizontally polarized and V vertically. For a V polarized beam the electric field oscillates in direction from up to down every half wavelength of propagation. But it never ceases to be V polarized. Reference any optics textbook. But: For experiments in fibre, polarization can change during propagation, and depends on the temperature of the fibre. So for those experiments it is necessary to calibrate some polarization directions.

So: the calculations must depend on the medium.
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Re: Calculations of QM prediction of -a.b

Postby FrediFizzx » Wed Nov 25, 2020 10:11 am

A somewhat better approach but not quite there. The spatial part of the wavefunction can be represented by where V is volume so for the standard QM calculation, we would have a 1/V factor on the -a.b result. So, what is V? Is the diameter of that volume the distance between a and b?
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Re: Calculations of QM prediction of -a.b

Postby FrediFizzx » Wed Nov 25, 2020 10:47 am

FrediFizzx wrote:A somewhat better approach but not quite there. The spatial part of the wavefunction can be represented by where V is volume so for the standard QM calculation, we would have a 1/V factor on the -a.b result. So, what is V? Is the diameter of that volume the distance between a and b?
.

IOW, the specification of the wavefunction would be,



But there is nothing there that ties in the distance between a and b. So, this volume could just be a small local volume.
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Re: Calculations of QM prediction of -a.b

Postby FrediFizzx » Wed Nov 25, 2020 12:12 pm

Hold your horses! When the observables happen, the singlet wavefunction is broken so it seems like the standard QM calculation that I presented is a farce to start with.
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Re: Calculations of QM prediction of -a.b

Postby FrediFizzx » Wed Nov 25, 2020 2:53 pm

FrediFizzx wrote:Hold your horses! When the observables happen, the singlet wavefunction is broken so it seems like the standard QM calculation that I presented is a farce to start with.
.

So, the prediction can also be obtained from the outcome pair probabilities. Anyone got a reference as to how those are derived?
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Re: Calculations of QM prediction of -a.b

Postby Joy Christian » Wed Nov 25, 2020 3:18 pm

FrediFizzx wrote:
FrediFizzx wrote:Hold your horses! When the observables happen, the singlet wavefunction is broken so it seems like the standard QM calculation that I presented is a farce to start with.

So, the prediction can also be obtained from the outcome pair probabilities. Anyone got a reference as to how those are derived?

See Appendices A and B of GHSZ for the derivations: https://aapt.scitation.org/doi/10.1119/1.16243
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Re: Calculations of QM prediction of -a.b

Postby FrediFizzx » Wed Nov 25, 2020 4:40 pm

Joy Christian wrote:
FrediFizzx wrote:
FrediFizzx wrote:Hold your horses! When the observables happen, the singlet wavefunction is broken so it seems like the standard QM calculation that I presented is a farce to start with.

So, the prediction can also be obtained from the outcome pair probabilities. Anyone got a reference as to how those are derived?

See Appendices A and B of GHSZ for the derivations: https://aapt.scitation.org/doi/10.1119/1.16243
.

Oh yeah, I knew I had seen that before. Thanks.

Image

Looks like there is a typo in (B4a). So, nhat_1 = a and nhat_2 = b.
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Re: Calculations of QM prediction of -a.b

Postby FrediFizzx » Wed Nov 25, 2020 6:18 pm

FrediFizzx wrote:
Joy Christian wrote:
FrediFizzx wrote:So, the prediction can also be obtained from the outcome pair probabilities. Anyone got a reference as to how those are derived?

See Appendices A and B of GHSZ for the derivations: https://aapt.scitation.org/doi/10.1119/1.16243
.

Oh yeah, I knew I had seen that before. Thanks.

Image

Looks like there is a typo in (B4a). So, nhat_1 = a and nhat_2 = b.
.

Unfortunately, this derivation is suspect also since the results are after the polarizer action. That means eq. (B3) is crashed already so how can it still be used?
.
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Re: Calculations of QM prediction of -a.b

Postby Austin Fearnley » Thu Nov 26, 2020 3:29 am

Fredifizzx wrote
Unfortunately, this derivation is suspect also since the results are after the polarizer action. That means eq. (B3) is crashed already so how can it still be used?

There is a very good related question, which is 'what is the effect of polarisation on the (say) electron'? For me that is a third good point to tell us something about the structure of the electron.

Assume the electron spin direction can be represented by EITHER a static arrow OR a dynamic arrow. Which is it to be?

1. Bell's Theorem [assume it is true, for the moment] rules out a static arrow in normal R3 space.

I have never obtained -0.707 for the Bell correlation in a simple simulation of static, fixed vector spin arrow directions. And that does not disagree with Bell's Theorem.

2. The Quantum Randi challenge is anathema to some here. But it does reinforce that using static arrows for spin vectors cannot give the Bell correlation of -0.707. It implies that there is some randomness in the measurement outcomes of A and B. That could fit in with the use of a dynamic arrow rather than a static one.

3. What is the effect of polarisation on the (say) electron?

For the static arrow model, if Alice measures the electron as UP and then measures it again at UP then the measurement has always the same outcome. That is true in the laboratory. It is also true for a dynamic arrow as long as the randomness is confined to always point within one hemisphere.

But what if the second measurement by Alice is made at 45 degrees to UP? Using a static model, the second measurement would always agree with the first measurement. But this is clearly not what happens in the laboratory. A dynamic model allows some variation between first and second measurements and this is what happens in nature.

.....

Think of a dynamic electron spin as represented by an unfurled umbrella.
See:
http://www.grandvoyageitaly.com/uploads ... a_orig.jpg
for an image of electrons polarised in the UP direction.

A furled umbrella would represent a static model with just the cane or handle showing. To polarise an electron as UP requires the cane to point upwards. But the fabric of the open umbrella shows all the possible spin directions still allowed in the dynamic model depite the overall UP polarisation.

I think that Fredifizzx's question is along the same lines. That is if you polarise first and then make a later measurement, then that measurement must agree with that polarisation if using a static model. With a dynamic model, however, polarisation never enforces a single static spin direction on an electron.

A dynamic model would overcome a number of issues with Bell and Randi and polarisation but is not enough on it own to give the Bell correlation.

......

The details are in my retro-model paper so I will not repeat in full here. But to get the Bell correlation needs Alice to measure an electron pre-polarised in the spin direction used by Bob when he measured the partner positron.

It is also tempting to think that entanglement is a magic ingredient to take you from (abs) correlation 0.5 to correlation 0.7 by an input of extra precision. And somehow linking that extra precision to their exactly opposite spin vectors. In fact, the Bell correlation is exactly dual to the Malus intensity formula, and entanglement plays no role in the Malus formula. So in an experiment one ought to need a lot of pairs to get an exact Bell correlation using the Law of Large numbers.

It is also odd to think that adding randomness can somehow increase precision from 0.5 to 0.7. Yet entanglement as the procurer of 0.7 is a red herring. The solution is an exactly correct pre-polarisation (via retrocausality) which overcomes the fuzziness induced by randomness in a dynamic model of the electron.

The photon can be modeled by a ladies' umbrella which does not cover a full hemisphere.
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Re: Calculations of QM prediction of -a.b

Postby FrediFizzx » Thu Nov 26, 2020 8:11 am

FrediFizzx wrote:
FrediFizzx wrote:
Joy Christian wrote:See Appendices A and B of GHSZ for the derivations: https://aapt.scitation.org/doi/10.1119/1.16243
.

Oh yeah, I knew I had seen that before. Thanks.

Image

Looks like there is a typo in (B4a). So, nhat_1 = a and nhat_2 = b.
.

Unfortunately, this derivation is suspect also since the results are after the polarizer action. That means eq. (B3) is crashed already so how can it still be used?
.

In fact, I have to say that eq. (B3) is flat out wrong. They have already replaced the particle spin vectors with a and b which means after the polarizer action. But after the polarizer action the singlet wavefunction doesn't exist. Plus those replacements would have to be +/-n. So, most likely any calculation of the prediction that uses the singlet wavefunction is no good! The QM calculation has to be done with separate measurement functions like in this paper,

EPRsims/QM_local_functions__Draft.pdf

The singlet wavefunction is not used.
.
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Re: Calculations of QM prediction of -a.b

Postby FrediFizzx » Thu Nov 26, 2020 3:01 pm

I suppose one could resort to hypotheticals for this to go through. The particle spin vectors just happen to line up with a and b. Though the actual probability of that happening is probably close to zero. So, all the QM predictions are hypothetical. But wait a minute... the spin vectors could only line up when a = -b so more restrictive.
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