Photon entanglement and fair sampling assumption

In summary, the discussion about correctness of fair sampling assumption in photon entanglement experiments is avoided for reasons of lack of creditability. I would like to ask if there are others who share this view?
  • #71
zonde said:
There are of course 3 simultaneous values for Alice at 0, 45, 67.5 - they are calculated independently for Alice and Bob. But it does not mean that all pairs are detected at 0 deg.

Let me illustrate this. We have photon pair that have the same POL value but it is off by 45 deg from polarizers of Alice and Bob. Depending from PH value photons are detected or not. But PH value for photons in pair is different (according to model) so depending from PH values of photons both of them could be detected or only one photon from pair can be detected (no coincidence) or both photons can be undetected (this case can not result in detected coincidence if we manipulate only Bob's polarizer or only Alice's polarizer).
Let's say we detected Bob's photon but didn't Alice's. Now we turn Alice's polarizer by 45 deg and sure enough now we detect Alice's photon and we have coincidence that didn't showed up at 0 deg measurement.

So you don't detect all relevant pairs (for possible 45 and 67.5 coincidences) at 0 deg according to model.

I am OK with you not detecting all of the relevant pairs (because you have a subset). But for subset of the ones you DO detect, you should be able to see the values for all 3 angles. That is the essence of realism.
 
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  • #72
akhmeteli said:
DrChinese.
Thank you very much for a prompt a detailed reply. Let me try to comment.

1. Indeed, if your theory has two contradictory conclusions, or assumptions, that means the theory is, strictly speaking, wrong. By the way, for this very reason quantum theory, in the specific form used to prove the Bell theorem, is, strictly speaking, wrong. Mathematically wrong. It does contain two contradictory assumptions. One of these assumptions must be wrong – logic does not allow any other conclusion. Specifically, I believe that unitary evolution (UE) is right, and the projection postulate (PP) is, strictly speaking, wrong. This is just my opinion, so you may agree or disagree, but you just cannot have both UE and PP, for the simple reason that they contradict each other, and you don’t seem to dispute that. If you do, please advise. In the following I won’t repeat this caveat and will assume that it is PP that is wrong. PP may be a good approximation, it may be a very good approximation, it may be an excellent approximation, it may be an amazingly great approximation, but the bottom line is it’s just an approximation. It just cannot be precise, because if it is, then UE has its share of problems.

2. Maybe I don’t quite understand you, or my English fails me, but I don’t quite see what is wrong about going against the weakest argument of the opponent. I would think in any contest the opponent’s weakest point is fair game. Furthermore, we are not in a court room, I think we both are just trying to understand something better, so I would think we should just agree with each other’s strongest argument, rather than waste time refusing to concede what we believe is actually correct in the opponent’s arguments.

3. I don’t quite get it. Such people as Shimony and Zeilinger, who are no fans of LR, admit that the “detection loophole” (and, consequently, the fair sampling assumption) presents a serious problem (see the relevant quotes at https://www.physicsforums.com/showpost.php?p=1702189&postcount=13 and https://www.physicsforums.com/showpost.php?p=1705826&postcount=65 ). Do you really believe we should accept the fair sampling assumption without discussion? You yourself gave an example where this assumption may be less than obvious – “An example would be celestial objects used as "standard candles".” I guess the following reasoning by Santos makes some sense: “In the context of LHV theories the fair sampling assumption is, simply, absurd. In fact, the starting point of any hidden variables theory is the hypothesis that quantum mechanics is not complete, which essentially means that states which are considered identical in quantum theory may not be really identical. For instance if two atoms, whose excited states are represented by the same wave-function, decay at different times, in quantum mechanics this fact may be attributed to an ”essential indeterminacy”, meaning that identical causes (identical atoms) may produce different effects (different decay times). In contrast, the aim of introducing hidden variables would be to explain the different effects as due to the atomic states not being really identical, only our information (encapsuled in the wave-function) being the same for both atoms. That is, the essential purpose of hidden variables is to attribute differences to states which quantum mechanics may consider identical. Therefore it is absurd to use the fair sampling assumption -which rests upon the identity of all photon pairs- in the test of LHV theories, because that assumption excludes hidden variables a priori.”

4. I agree, there are “new and improved Bell tests every year”. However, so far the result is always the same: no violation of the genuine Bell inequalities. For some reason there is always something: either the detection loophole, or locality loophole, you name it. 45 years and counting – no violations. That reminds me the following words from Heller’s “Catch-22”:
"I've got just the twelve-year-old virgin you're looking for," he announced jubilantly. "This twelve-year-old virgin is really only thirty-four, but she was brought up on a low-protein diet by very strict parents and didn't start sleeping with men until"

5. I don’t know, I fail to see how entanglement can eliminate LR, as existence of entanglement is not enough to prove the Bell theorem. You need the projection postulate. You are a knowledgeable person, so I am sure you appreciate that “entanglement of particles that are outside of each other's light cones” per se does not eliminate LR. In general, the only thing that could be fatal to LR is genuine BIV (that is, if we forget about superdeterminism). So far genuine BIV have not been demonstrated, and I don’t hold my breath.

I don’t get it. I specifically indicated the two mutually contradictory assumptions that are both predictions of QM and necessary to prove the Bell theorem. So while I could agree that “If you think QM itself is based on mutually contradictory assumptions (which some claim is the case), that is NOT equivalent to saying Bell itself is based on those assumptions.”, this is not relevant, because the proof of the Bell theorem is indeed based on two mutually contradictory assumptions, and I specifically indicated that, showing where the proof uses UE and PP. As for the cos^2(theta) rule, when you use it for both particles of the singlet, I believe you need the projection postulate (to count the QM correlations), and PP directly contradicts UE.

6. I don’t know. My impression was that the Copenhagen interpretation’s grip on physics was much stronger then than now. But I may be mistaken.

7. Again, entanglement does not eliminate LR. And Einstein is no relative of mine. It is my understanding he opposed the uncertainty principle. So he was wrong on this issue (at least I believe so). But the uncertainty principle per se does not eliminate LR either. On the other hand, Einstein’s EPR paper led to significant progress.

8. I readily admit that I don’t know much about GHZ, Leggett etc., but I suspect they basically have the same problems as the Bell theorem. For example, I have not heard anybody state that they were successfully used to conduct loophole-free experiments eliminating LR.

My assessment is there are neither no-go theorems nor experimental data eliminating LR. But I certainly respect your point of view.

1. QM is not considered self contradictory, although a lot of folks don't like the collapse rules. But that is 100% irrelevant to Bell's Theorem, which merely points out that the predictions of QM and LR are different in specific areas. One has nothing to do with the other, and it is plain wrong to say "Bell is inconsistent because QM is inconsistent".

2. The answer is that it doesn't convince anyone. Which explains why the LR position is completely ignored professionally except by Santos and a few others.

3. True, they have elevated the detection loophole to a higher status. They even published a paper with Santos on the subject. For the reasons ZapperZ explained about loopholes above, I respectfully disagree with their assessment; but I understand their position as being for the sake of bringing a final and complete end to the "loopholes" discussion. I think Santos' statement you quote is ridiculous, I have seen it before and it always makes me mad. No one is a priori ignoring hidden variables. If they existed, context free, they should be noticable and yet they never are. There is absolutely NOTHING about the setups that can be said to select a subset which is biased in any way. If such bias occurs, it must be natural and subtle (like my standard candles example). The problem with that approach is that even then, there is NO known way to get the Bell results from a biased LR sample... as we see with Santos' repeated failures. And as detection efficiency improves: the Bell result simply gets stronger in complete violation of LR predictions. And finally, there is substantial independent corroboration from other experiments.

4. You are completely wrong again, the violations are there every time. The thing you ignore is called the scientific method. There is no requirement in the method - EVER - that all loopholes be closed simultaneously to accept the results of an experiment. I would say in fact that this almost NEVER occurs in any scientific experiment. The normal technique is to vary one variable at a time and chart relationships. That is why science accepts the Bell test results. If everyone stuck their heads in the ground until "perfect" experiments were done (as you seem to suggest), we would have no science at all.

5. Now you are just trying to be contradictory. You say that correlations outside of Alice and Bob's light cones are within the scope of LR? As far as I know, there has not been any attempt by a local realist to address that one. Once again, your argument circles back to "I ignore all evidence in contradiction to my viewpoint" even though this one completely contradicts every possible LR perspective.

6. The local realistic school, of which Einstein was a member, is virtually non-existent now. So you are wrong again. QM has more interpretations now, but they are all either non-local or non-realistic.

7. Of course entanglement refutes LR. That is by definition! Or more precisely, LR flatly predicts that entanglement does not exist (correlations are spurious).

8. As with Bell, the other no-gos compare the predictions of LR with the predictions of QM. They use different techniques, and they are generally not statistical. They are instead considered "all-or-nothing" and soundly support QM. I guess you will next tell us that is even more support for LR because QM is contradictory and should not be supported.

You see, your starting premise - that QM is contradictory - flies in the face of the science of the last 100 years. While you see problems, everyone else is using the theory to make new predictions and new advances. That is because QM is useful. Now, is it also true? That is not a scientific question, it is a philosophical one. QM is a model, and should not be confused with reality. See my tag line below.
 
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  • #73
akhmeteli said:
The problem of measurement in QM is well-known.

Apparently not as well known as you seem to think. I probably saw 10 papers last year on that subject (measurement problems), compared to perhaps 1000 on entanglement. So I would say the problem you identify is much less of a problem for the practicing physicist than you suggest.

Why don't you start a separate thread on the subject? Then we could discuss the evidence for your perspective.
 
  • #74
zonde said:
Well, it took some time
...
Probability that there is photon with given values of hidden variables:
abs(sin(2*ph))

Polarization of photon i.e. will it pass the polarizer or not (+ sign for it will pass):
sign(sin(alpha + pol)^2 - cos(ph)^2)
this function actualy determines whether polarizer angle falls in "passing" interval or in "absorbing" interval of photon so it can be described with intervals without using sine and cosine functions.

Detection (+ sign for it will be detected):
sign(cos(ph)^2-K) where K=sin(Pi/8)^2
again determines whether "ph" falls in certain interval and so can be described without cosine function
...
I have tried to incorporate your model in simulation program (basically I have used the one from de Raet mentioned earlier and made it more object oriented). Would you say the code below represents your proposal for the effect of the filter on a particle (I hope it is clear enough)?

Code:
       private void ParticleHitfromZonde(Particle Particle)
        {
            bool Pass = true;
            double HvProbability = Math.Abs(h.Sin(Particle.StaticPhaseDifference)); //Calculate HvProbability

            if (HvProbability < h.GetRandom())                                      //Get a random value between 0 and 1 
                                                                                    // and check whether HvProbability is lower
            {
                Pass=false;
            }
            if (Pass)
            {
                //user other proposed formulas:
                int WillItPass = Math.Sign(h.SinSquare(this.Angle + Particle.Polarization) - h.CosSquare(Particle.StaticPhaseDifference));
                int Detection = Math.Sign(h.CosSquare(Particle.StaticPhaseDifference) - h.SinSquare(h.PiOver8));
                if (WillItPass < 0 || Detection < 0)
                {
                    Pass = false;
                }
            }
            Particle.Absorbed = !Pass;                                              //Absorbed is opposite of pass

        }
(this.Angle is the angle of the polarization filter)
 
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  • #75
ajw1 said:
I have tried to incorporate your model in simulation program (basically I have used the one from de Raet mentioned earlier and made it more object oriented). Would you say the code below represents your proposal for the effect of the filter on a particle (I hope it is clear enough)?

Code:
       private void ParticleHitfromZonde(Particle Particle)
        {
            bool Pass = true;
            double HvProbability = Math.Abs(h.Sin(Particle.StaticPhaseDifference)); //Calculate HvProbability

            if (HvProbability < h.GetRandom())                                      //Get a random value between 0 and 1 
                                                                                    // and check whether HvProbability is lower
            {
                Pass=false;
            }
            if (Pass)
            {
                //user other proposed formulas:
                int WillItPass = Math.Sign(h.SinSquare(this.Angle + Particle.Polarization) - h.CosSquare(Particle.StaticPhaseDifference));
                int Detection = Math.Sign(h.CosSquare(Particle.StaticPhaseDifference) - h.SinSquare(h.PiOver8));
                if (WillItPass < 0 || Detection < 0)
                {
                    Pass = false;
                }
            }
            Particle.Absorbed = !Pass;                                              //Absorbed is opposite of pass

        }
(this.Angle is the angle of the polarization filter)

A couple of questions:

1. Each particle has properties .StaticPhaseDifference and .Polarization - are there any others?
2. Also, is .Polarization randomly assigned or similar?
3. What about .StaticPhaseDifference? How is its value assigned?

I want to follow the analogy myself because I am concerned about sleight of hand that subtly puts in a non-local factor.
 
  • #76
DrChinese said:
A couple of questions:

1. Each particle has properties .StaticPhaseDifference and .Polarization - are there any others?
2. Also, is .Polarization randomly assigned or similar?
3. What about .StaticPhaseDifference? How is its value assigned?

I want to follow the analogy myself because I am concerned about sleight of hand that subtly puts in a non-local factor.

1. Currently I have no other properties for the particles except .Absorbed and .DelayTime (the delaytime is used for the de Raet model)
2 and 3. On creation, both the properties get a random value between 0 and 2pi. Then the properties of the second one is then related to that of the first one as specified by Zonde

Code:
    public class Particle
    {
        public Particle()
        {
            this.Polarization = h.GetRandomTwoPiAngle();
            this.StaticPhaseDifference = h.GetRandomTwoPiAngle();
        }


Code:
                //Initiate entangled particles
                Particle Particle1 = new Particle();
                Particle Particle2 = new Particle();

                //polarization relation
                Particle2.Polarization = Particle1.Polarization + h.PiOver2; // polarization of particle 2

                //Zonde
                Particle2.StaticPhaseDifference = Particle1.StaticPhaseDifference + h.PiOver4; // polarization of particle 2
I can attach all the classes, or, when you have access to a Visual Studio environment, the complete project
 
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  • #77
You have Particle2.StaticPhaseDifference = Particle1.StaticPhaseDifference + h.PiOver4;

Is the piOver4 correct? Or is it supposed to be piOver2 as is polarization? That may be OK, I want to make sure though. It seems strange not to make them identical, when that is the premise.
 
  • #78
DrChinese said:
You have Particle2.StaticPhaseDifference = Particle1.StaticPhaseDifference + h.PiOver4;

Is the piOver4 correct? Or is it supposed to be piOver2 as is polarization? That may be OK, I want to make sure though. It seems strange not to make them identical, when that is the premise.
Yes, you're probably right:
zonde said:
... Here I just hypothesize that "phase" vectors are orthogonal for entangled pair...
The spreadsheet code however seems to be using PiOver4, or maybe I am missing something...
 
  • #79
I tried to follow the De Raedt example from the web site, but they hide their algorithm and dataset. I see some formulas here and there but how do you know what to do unless you can see the code? It should be very simple/straightforward - like yours - but I cannot find it. I do see a downloadable app but it is an EXE so I probably won't see how the data is generated. Oh well, I guess I will check it out.
 
  • #80
DrChinese said:
I tried to follow the De Raedt example from the web site, but they hide their algorithm and dataset. I see some formulas here and there but how do you know what to do unless you can see the code? It should be very simple/straightforward - like yours - but I cannot find it. I do see a downloadable app but it is an EXE so I probably won't see how the data is generated. Oh well, I guess I will check it out.

Their (Fortran) code is at the end of http://rugth30.phys.rug.nl/pdf/COMPHY3339.pdf"
 
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  • #81
ajw1 said:
Their (Fortran) code is at the end of http://rugth30.phys.rug.nl/pdf/COMPHY3339.pdf"

Excellent, thanks. This should allow me to understand what they are doing. I am working on understanding the code and should be able to provide an explanation of how it works. I should also be able to verify if realism is respected by the model, which is of course a requirement.
 
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  • #82
ajw1 said:
Their (Fortran) code is at the end of http://rugth30.phys.rug.nl/pdf/COMPHY3339.pdf"

Can you help me decipher this statement:

k2=ceiling(abs(1-c2*c2)**(d/2)*r0/tau) ! delay time

this looks to me like:

k2=ceiling(abs(1-(c2*c2))**((d/2)*(r0/tau))) ! delay time

and since d=2 and static reduces to:

k2=ceiling( abs(1-(c2*c2))**(r0/tau) ) ! delay time

------------------------------------------------------------------------

After examining this statement, I believe I can find an explanation of how the computer algorithm manages to produce its results. It helps to know exactly how the bias must work. :smile: The De Raedt et al model uses the time window as a method of varying which events are detected (because that is how their fair sampling algorithm works). That means, the time delay function must be - on the average - such that events at some angle settings are more likely to be included, and events at other angle setting are on average less likely to be included. It actually does not matter what physical model they propose, because eventually they must all accomplish the same thing. And that is: the bias function must account for the difference between the graphs of the QM and LR correlation functions.

Which is simply that we want the difference between the LR correlation function and the QM correlation function to be zero at 0, 45, 90, 135 degrees. That is because there is no difference in the graphs at those angles. But there is a difference at other angles. That same difference must be positive and maximum at angles like 22.5, 157.5 etc, and be negative and minimum at angles like 67.5 and 112.5 etc. (Or maybe vice versa :smile: )

So we need an embedded bias function that has those parameters, and if their computer program is to work, we will be able to find it. Once we find it, we can then assess whether it truly models the actual experimental data. If we see it does, they win. Otherwise, they lose. Of course, my job is to challenge their model. First, I must find out how they do it.

So we know that their function must: i) alternate between positive and negative bias, ii) it must have zero crossings every 45 degrees (pi/4), and iii) it must have a period of 90 degrees (pi/2). It does not need to be perfect, because the underlying data isn't going to be perfect anyway. Any of this starting to look familiar? Why yes, that is just the kind of thing we saw in zonde's model.
 
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  • #83
So now, per my prior post on the De Raedt model:

Let's assume I can demonstrate how the bias function uses the delay to do its work (by affecting which events are within the time window and therefore counted). The next question is: does it model all of the data of relevant Bell tests? Well, yes and no. Obviously they claim to produce QM-like data as far as was reported - YES in this regard. But most likely we will see that the traditional Bell test experimenters did not consider this clever twist - some perhaps NO in some way. It should be possible to extend the actual experiments to show whether the De Raedt model is accurate or not. In fact, I believe I can show this without performing an experiment once I run their algorithm myself.

I think I can safely give the De Raedts an A for coming up with a simulation that works as it does. As I have said previously, a simulation which produces a QM-like result is NOT the same as a local realistic theory. So such a simulation - ALONE and BY ITSELF - is NOT a disproof of the Bell Theorem. Because there are additional consequences of any local realistic theory, and if those are not considered then it cannot be a candidate. Again, this is why Santos has failed with stochastic models.
 
  • #84
DrChinese said:
Can you help me decipher this statement:

k2=ceiling(abs(1-c2*c2)**(d/2)*r0/tau) ! delay time

this looks to me like:

k2=ceiling(abs(1-(c2*c2))**((d/2)*(r0/tau))) ! delay time

and since d=2 and static reduces to:

k2=ceiling( abs(1-(c2*c2))**(r0/tau) ) ! delay time


The model produces the expected results when you use only d/2 for the power (exponent):
(1-c22) d/2
and then muliply with r0/tau (I had the same problem, so I used a fortran debugger to check the calculation. Attached a graph of my simulation. Green is when one only assumes Malus for the photons (without timetag))
 

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  • #85
ajw1 said:
The model produces the expected results when you use only d/2 for the power:
(1-c22) d/2
and then muliply with r0/tau (I had the same problem, so I used a fortran debugger to check the calculation. Attached a graph of my simulation. Green is when one only assumes Malus for the photons (without timetag))

So verifying that we: DO multiply the entire result by r0/tau, and do NOT multiply the exponent d/2 by r0/tau?

Graph looks great by the way.
 
  • #86
DrChinese said:
So verifying that we: DO multiply the entire result by r0/tau, and do NOT multiply the exponent d/2 by r0/tau?
That is correct
 
  • #87
ajw1 said:
That is correct

Thanks. I should have some more soon.
 
  • #88
DrChinese said:
I am OK with you not detecting all of the relevant pairs (because you have a subset). But for subset of the ones you DO detect, you should be able to see the values for all 3 angles. That is the essence of realism.
Yes of course. What else I can say.
Detection values are calculated separately for Alice and Bob and coincidences again are calculated row by row taking only one value from Bob's data and one value from Alice's data. Final result is sum of coincidence values in all rows. All rows produce some result either 0 or some positive value.

I suppose that only satisfactory answer for you is to test the model yourself.
 
  • #89
ajw1 said:
I have tried to incorporate your model in simulation program (basically I have used the one from de Raet mentioned earlier and made it more object oriented). Would you say the code below represents your proposal for the effect of the filter on a particle (I hope it is clear enough)?

Code:
            double HvProbability = Math.Abs(h.Sin(Particle.StaticPhaseDifference));
It seems to me that there is missing *2 in that row (should be Particle.StaticPhaseDifference*2, not sure about syntax). Everything else seems ok.
 
  • #90
DrChinese said:
4. You are completely wrong again, the violations are there every time. The thing you ignore is called the scientific method. There is no requirement in the method - EVER - that all loopholes be closed simultaneously to accept the results of an experiment. I would say in fact that this almost NEVER occurs in any scientific experiment. The normal technique is to vary one variable at a time and chart relationships. That is why science accepts the Bell test results. If everyone stuck their heads in the ground until "perfect" experiments were done (as you seem to suggest), we would have no science at all.
Good argument about addressing loopholes separately. But for that to work experiments should be basically the same. That is not the case with violations of Bell inequalities.
Another good method is to vary certain parameter in question and analyze how results depend from this parameter.
So in this case it would be good to see photon experiments where detection efficiency is varied and coincidence rate (along with correlations) is analyzed. And for experiments with efficient detection distance between two entities would be the varying parameter.
But of course experiments like that would be quite challenging because of additional errors that should be taken into account when parameter in question is varied (in case of photons and even more challenging for efficient detection) so we might not see them soon if ever.
 
  • #91
zonde said:
Good argument about addressing loopholes separately. But for that to work experiments should be basically the same. ...

Once the hypothetical effect is demonstrated (not to exist), there is no requirement that the setup be identical for each effect separately. That is generally accepted science, and that is why no experiment can be said to be truly loophole free.

Now, here is the admittedly far-fetched possibility. I call it the "combination safe" analogy. We have a combination safe which has 2 (or more) digits. The analogy is that each digit is a different test loophole. Knowledge of the first digit is not enough to open the safe. Knowledge of the second digit is not enough to open the safe. You must know both (loopholes) simultaneously to open the safe and find the loot inside. This is technically possible, again for any experiment, although there are some strict requirements for the loopholes in such case. They must themselves have a relationship (i.e. they cannot be fully independent).
 
  • #92
DrChinese said:
Once the hypothetical effect is demonstrated (not to exist), there is no requirement that the setup be identical for each effect separately. That is generally accepted science, and that is why no experiment can be said to be truly loophole free.
Two setups don't have to be identical but they should be comparable so that observations in first experiment could be reasonably extended to second experiment.
So they should share significant part of setup between them.

But that is not the case with photon Bell tests and mater Bell tests. There the setups are radically different.
 
  • #93
I rewrote the algorithm without these numerous sines and cosines squared. Do not know if it's interesting.

But another thing is that thinking about physical interpretation of this model, detector efficiency does not come into play in any way - there can be fair sampling at detectors.
The core of unfair sampling comes from specific local interaction (interference) at polarizer of photon's own context wave with entangled photon's empty context wave traveling with the photon.
That seems more in line with QM.
 
  • #94
zonde said:
I rewrote the algorithm without these numerous sines and cosines squared. Do not know if it's interesting.

But another thing is that thinking about physical interpretation of this model, detector efficiency does not come into play in any way - there can be fair sampling at detectors.
The core of unfair sampling comes from specific local interaction (interference) at polarizer of photon's own context wave with entangled photon's empty context wave traveling with the photon.
That seems more in line with QM.
I'm surely interested, Maybe you can just attach a spreadsheet file with the significant lines included (all lines filled will produce probably a very large file)
 
  • #95
ajw1 said:
I'm surely interested, Maybe you can just attach a spreadsheet file with the significant lines included (all lines filled will produce probably a very large file)

I am working on a spreadsheet version using Excel.
 
  • #96
ajw1 said:
i'm surely interested, maybe you can just attach a spreadsheet file with the significant lines included (all lines filled will produce probably a very large file)

https://www.physicsforums.com/attachments/23167
I am using manual recalculation settings in excel when working with models.
Another change in this file is that uneven distribution of PH values is achieved right at generation of it's values (you will notice that arccos function is used there). And it is joined distribution for both photons because that seems to make more sense than non-matching distributions of two photons.
And PH value is directly expressed as size of the interval for angles where photon will pass polarizer.
 
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  • #97
I have put together a model that generates the attached values when run for the range 0 to 90 degrees, incrementing by 1, and 5000 iteratations for each pair of angles. The coincidence time window is k=30 ns (scaling is by algorithm). This is a good representation of their model for Type II PDC, and follows their formula faithfully.

The purple line shows the sample, which is "close" to the QM predicted values (close being relative - keep in mind that Bell tests do not match the QM predictions perfectly either). This matches what they wanted for their model. The green line shows the full universe plot, which respects the Bell Inequality. This also matches what they wanted for their model. A few points to keep in the back of your mind as the discussion continues:

a. Because their full universe matches the LR boundary condition (so as to obey Bell), it obviously does NOT respect Malus. You can see that on the chart. So that is a nasty little issue to deal with. That is one of the reasons that folks say that no LR theory can agree with ALL of the predictions of QM. I think it has been long realized that this would be a result of any algorithm that could address the entanglement side of things.

b. Also, while it appears from the attached chart that Bell's Inequality is not violated for the full sample... that too is somewhat misleading. My spreadsheet documents the event by event portion in an explicitly realistic fashion. It accomplished this by displaying the results of every iteration for any trial you want to run. It then models what happens if you could test particle 2 at an extra angle setting, 45 degrees offset to the main setting for particle 1. So such simulation shows a total of 3 measurements. Only 2 are physically possible in an actual experiment, but in the computer program 3 are possible while respecting the model. Because the LR boundary condition only works when there are NO events of a certain type, the presence of those events could mean that Bell's Inequality is violated after all. I will have a picture of this shortly in case the reasoning is not clear from my verbage.

c. I should soon have a diagram showing my original objection to their model describing at the beginning of this thread. That being that their model does not handle photon pairs that are not polarization entangled, although they explicitly claim it does. That cannot be seen from this chart.
 

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  • #98
DrChinese said:
The purple line shows the sample, which is "close" to the QM predicted values (close being relative - keep in mind that Bell tests do not match the QM predictions perfectly either). This matches what they wanted for their model. The green line shows the full universe plot, which respects the Bell Inequality. This also matches what they wanted for their model.
Result does not seem very good. I think it should fluctuate around QM prediction but it is constantly closer to straight line. Isn't it so?

DrChinese said:
A few points to keep in the back of your mind as the discussion continues:

a. Because their full universe matches the LR boundary condition (so as to obey Bell), it obviously does NOT respect Malus. You can see that on the chart. So that is a nasty little issue to deal with. That is one of the reasons that folks say that no LR theory can agree with ALL of the predictions of QM. I think it has been long realized that this would be a result of any algorithm that could address the entanglement side of things.
This can not be seen from graph because reference in the graph is relative polarization angle between two photons and not polarization of individual photons of one side relative to polarizer. The model is silent about that so it can not be judged by that.

DrChinese said:
b. Also, while it appears from the attached chart that Bell's Inequality is not violated for the full sample... that too is somewhat misleading. My spreadsheet documents the event by event portion in an explicitly realistic fashion. It accomplished this by displaying the results of every iteration for any trial you want to run. It then models what happens if you could test particle 2 at an extra angle setting, 45 degrees offset to the main setting for particle 1. So such simulation shows a total of 3 measurements. Only 2 are physically possible in an actual experiment, but in the computer program 3 are possible while respecting the model. Because the LR boundary condition only works when there are NO events of a certain type, the presence of those events could mean that Bell's Inequality is violated after all. I will have a picture of this shortly in case the reasoning is not clear from my verbage.
Picture might help. But from what I understood there is nothing wrong with LR model if it can demonstrate different angle settings for one side while keeping the other side intact. That just makes the point about element of reality present.
 
  • #99
zonde said:
1. Result does not seem very good. I think it should fluctuate around QM prediction but it is constantly closer to straight line. Isn't it so?

2. This can not be seen from graph because reference in the graph is relative polarization angle between two photons and not polarization of individual photons of one side relative to polarizer. The model is silent about that so it can not be judged by that.


3. Picture might help. But from what I understood there is nothing wrong with LR model if it can demonstrate different angle settings for one side while keeping the other side intact. That just makes the point about element of reality present.

1. It's not too bad. Ideally they would have something closer to the QM value. Because they achieve the result by the introduction of a random fluctuation, the amount is about halfway between.

You don't notice the issue on their graphs because they sample only at a few pairs of angle settings. My simulation fills in the gaps by running across 90 degrees by degree. To be fair, I do not consider their presentation in this regard misleading.

2. I don't agree.

3. After finishing the model last night, I checked this element out. It turns out the "suppressed cases" (2 of 8 permutations) worked out fine in their model, so as to not cause an issue.
 
  • #100
OK, I am attaching the XLSM file of my recreation of the De Raedt model to the other thread discussing the model explicitly. If it does not come across, send me a message with your email and I will send it to you directly. Anyone is welcome to look at the results. :smile:
 
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