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Fair Sampling Loophole now closed for Photons 
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#1
Dec412, 10:00 AM

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PF Gold
P: 5,299

A team including Anton Zeilinger has performed an experiment closing the socalled "fair sampling loophole" for photons.
http://arxiv.org/abs/1212.0533 Bell violation with entangled photons, free of the fairsampling assumption Marissa Giustina, Alexandra Mech, Sven Ramelow, Bernhard Wittmann, Johannes Kofler, Adriana Lita, Brice Calkins, Thomas Gerrits, Sae Woo Nam, Rupert Ursin, Anton Zeilinger (Submitted on 3 Dec 2012) "The violation of a Bell inequality is an experimental observation that forces one to abandon a local realistic worldview, namely, one in which physical properties are (probabilistically) defined prior to and independent of measurement and no physical influence can propagate faster than the speed of light. All such experimental violations require additional assumptions depending on their specific construction making them vulnerable to socalled "loopholes." Here, we use photons and highefficiency superconducting detectors to violate a Bell inequality closing the fairsampling loophole, i.e. without assuming that the sample of measured photons accurately represents the entire ensemble. Additionally, we demonstrate that our setup can realize onesided deviceindependent quantum key distribution on both sides. This represents a significant advance relevant to both fundamental tests and promising quantum applications." Previously, a Bell Inequality had been violated free of the fair sampling assumption using Be+ ions (2001). That team included 2012 Nobel prize winner David Wineland of NIST. This new experiment has the advantage of having been performed with photons. I anticipate that a future variation might be performed to close both the fair sampling AND the locality assumptions simultaneously. 


#2
Dec412, 01:48 PM

P: 724

Another conspiracy theory laid to rest. They've been beating a dead horse though.



#3
Dec412, 02:11 PM

PF Gold
P: 675

http://lanl.arxiv.org/ftp/arxiv/pape.../1203.6587.pdf 


#4
Dec412, 02:24 PM

Sci Advisor
PF Gold
P: 5,299

Fair Sampling Loophole now closed for Photons
I am excited though that this team was able to put this together. It seems that these experiments keep pushing the boundaries on overall understanding of entanglement. 


#5
Dec412, 11:10 PM

PF Gold
P: 1,376




#6
Dec512, 05:26 AM

P: 129




#7
Dec512, 09:14 AM

Sci Advisor
PF Gold
P: 5,299

On the other hand, I think Superdeterminists (like 't Hooft, esteemed as he is) have yet to demonstrate that their argument IS actually scientific in a traditional sense. I assert that Superdeterminism qualifies as a religion more than science: it is a belief that A THEORY COULD EXIST that would explain something rather than a falsifiable theory itself. I would challenge 't Hooft to demonstrate any concrete element of Superdeterminism that explains the mystery of the Bell results any better than it explains why we measure c to be a constant in any reference frame. (In other words, why Superdeterminism should be invoked for one scientific area and not all others, including as an explanation of human evolution.) For example, 't Hooft says in a recent paper: http://arxiv.org/abs/1207.3612 "Bell’s inequalities[1] and similar observations[2][3] are applied with mathematical rigor to prove that quantum mechanics will be the backbone of all theories for subatomic particles of the future, unless, as some string theorists have repeatedly stressed, “an even stranger form of logic might be needed”[4]. The author of this paper takes a minority’s point of view[5][6], which is that, in order to make further progress in our understanding of Nature, classical logic will have to be restored, while at the same time our mathematical skills will need to be further improved. We have reasons to believe that the mathematics of ordinary statistics can be rephrased in a quantum mechanical language and notation; indeed this can be done in a quite natural manner, such that one can understand where quantum phenomena come from." Basically, he is developing an ad hoc theory to explain behavior that is already described by another theory (quantum mechanics) with a particular nonstandard agenda (and he explicitly acknowledges this). Yet there is no explanation of why the same logic is not being applied elsewhere in science. Nor does it explain the hundreds of experiments evidencing entanglement. Instead he attempts to justify his position on heuristic grounds when there are obvious counterarguments to his position. So I question how this really qualifies as normal science; and to the extent it does, I would then say it IS a "science denier's" argument. I can't see any evidence his arguments (or Superdeterminism in general) are being seriously followed by the community, but I am subject to correction. About all you can say is that Superdeterminism is thrown around as an escape to Bell, without there being any serious discussion of how that could occur. You may as well qualify EVERY scientific theory as having Superdeterminism as an escape. 


#8
Dec612, 05:06 PM

P: 3,184




#9
Dec612, 07:01 PM

P: 1,583

This is really something! Now it's almost impossible for people to hide behind loopholes to evade Bell's theorem. Now they have to say something extreme, like "different loopholes explain different photon Bell tests", and that gets into superdeterministic territory, since the photons would have to somehow know in advance what loophole the experimenter is going to close in any given experiment.



#10
Dec612, 11:33 PM

PF Gold
P: 1,376

14. P. H. Eberhard, Background Level and Counter Efficiencies Required for a LoopholeFree EinsteinPodolskyRosen Experiment, Physical Review A 47, 747–750 (1993). link 18. J. F. Clauser, M. A. Horne, Experimental consequences of objective local theories, Physical Review D 10, 526–535 (1974). link But it seems that the proof of inequality that is used in the paper for interpretation of results is rather simple. Inequality (3) is: [tex]J=S(\alpha_1)+S(\beta_1)+C(\alpha_2,\beta_2)C(\alpha_1,\beta_1)C(\alpha_1,\beta_2)C(\alpha_2,\beta_1)\geqslant 0[/tex] I will check my proof and then I will post it here. 


#11
Dec712, 06:44 AM

P: 3,184




#12
Dec712, 01:13 PM

P: 1,583




#13
Dec812, 09:34 AM

PF Gold
P: 1,376

So the proof of inequality is in second paper "APPENDIX A: TWO INEQUALITIES" first part. It's very simple indeed. My version was about writing down all possible combinations of detections/nondetections at different settings and finding out that no combination can produce negative value. Like this:



#14
Dec812, 09:44 AM

PF Gold
P: 1,376

And I would like to see how it will pass peer review with calculation of standard deviation like it is presented in the paper. I would say it is invalid. 


#15
Dec812, 10:20 AM

P: 3,184




#16
Dec812, 01:34 PM

Sci Advisor
PF Gold
P: 5,299

Lacking objections per the above, you would not be likely to get a mentor to step in against the reference. On the other hand, you are free to deny it in private. 


#17
Dec812, 03:12 PM

P: 724

Wouldn't that qualify Zeilinger as a troll as well? There is a mystery only if one insists that qm be local realistic. It's your obligation to prove how that should be possible given all the evidence to the contrary. 


#18
Dec912, 01:03 AM

PF Gold
P: 1,376

Why I am obligated? And how should I do that when it's known since Bell theorem that it's not possible? 


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