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0answers
69 views

Bell's inequality, “complete plans” and spooky action at a distance

What am I proposing and asking? In Mermin's thought experiment entangled particles, i.e. photons are sent to two machines A and B with 3 settings each. The idea of a "complete plan" how to react to ...
4
votes
1answer
216 views

Entanglement, Bohr-Einstein Debate, Bell's Inequality

On BBC episode The Secrets of Quantum Physics (Part 1) Jim Al-Khalili explains quantum mechanics for the layman. In the first half, he does a very good job; in the second half, either he thought his ...
-4
votes
0answers
27 views

Testing Bell's inequality violated by quantum mechanics [closed]

I made this code to test Bell's inequality that violated by quantum mechanics that said the max value is 2*sqrt(2), but when i run, it gave me the max value only 2. so could you please tell me what i ...
1
vote
1answer
133 views

Is it enough to use only sigma criterion to calculate expected value for ideal Bell's test experiment?

Let's build some custom distribution for particle measurement result in CHSH test. Let's assume ideal particles and detectors. Let's also assume that each particle has hidden parameter $z$. Parameter ...
0
votes
3answers
83 views

Does Bell's theorem exclude local hidden variables as explanation for radioactive decay?

Often it is said that Bell's theorem (and the observed violations thereof) rules out local hidden variable theories as the explanation for the seeming non-determinism found in quantum mechanics. I'm ...
4
votes
1answer
497 views

Tracking down the locality assumption in a CHSH inequality derivation

CHSH inequality requires both locality and realism. I will equate here realism with counterfactual definiteness. Now counterfactual definiteness tells us that given two different measurements on the ...
5
votes
3answers
255 views

Why would classical correlation in Bell's experiment be a linear function of angle?

Sorry if it's a newbie question, but I have trouble understanding the following part in the Wikipedia's explanation for the Bell's theorem: With the measurements oriented at intermediate angles ...
3
votes
2answers
61 views

Non-locality vs. non-realism: Arbitrary choice?

After reading this question, I feel I understand why quantum mechanics is so confusing (and so often confused by the media): It can be either local (if A causes B, then there must be time for a signal ...
1
vote
0answers
38 views

Does the violation of Bell inequality by a classical field imply “classical entanglement”?

This article has been brought to my attention recently (free access) : Shifting the quantum-classical boundary: theory and experiment for statistically classical optical fields In the abstract, they ...
1
vote
1answer
55 views

Why can arbitrary two qubit density matrices be expressed in this form? [duplicate]

In the paper "Violating Bell inequality by mixed spin 1/2 states: necessary and sufficient condition" (http://www.sciencedirect.com/science/article/pii/037596019500214N#) by three Horodecki siblings, ...
3
votes
1answer
118 views

Was quantum mechanics made to fit the Bell violations or they just happen to fit them?

Entangled bipartite states can violate the CHSH inequality upto $2\sqrt{2}$ with suitable measurements. Is it that in nature we don't witness violation of CHSH more than this and quantum mechanics ...
0
votes
1answer
111 views

Does quantum theory obey locality?

Bell's inequality together with the Aspect experiment shows that that we cannot have local realism. But does quantum theory obey locality? and if not how can locality be violated but not special ...
1
vote
2answers
143 views

Is entanglement a classical phenomenon (last attempt)?

This is a reformulation of two previous questions that seem to have been misunderstood, or most likely, I failed to make them clear. I thank all people that answered, even the belligerent ones. Some ...
0
votes
1answer
20 views

Angular momentum conservation laws and GHZ article (Greenberger et al 1990)

Can anyone recommend a good book or an online source on angular momentum conservation laws in decay processes? I'm writing a master's thesis concerning Bell inequalities and currently working on GHZ ...
6
votes
6answers
307 views

Can quantum entanglement be simulated on a digital computer to any degree of precision?

First principles modelling of physical phenomena has been very successful in physics. The largest limitation is perhaps the fact that many QM problems are NP hard so we would need really powerful ...
4
votes
1answer
246 views

Do Bell inequality violations appear instantly when the source is turned on, or do they increase over time?

This experimental Question is a result of reading a particular article on Bell violations. I addressed the e-mail below to the corresponding authors —because who knows, they might reply— but it is not ...
3
votes
2answers
1k views

Can cellular automata be reconcilied with quantum mechanics?

CAs are deterministic representations of the universe, which, according to the Bell's inequality are not entirely accurate. Cells interact "locally" (only with the closest neighbours), while quantum ...
0
votes
1answer
84 views

Doesn't the concept of “hidden variables”, by definition, encompass all possible results? [closed]

While i don't know all the mathematical/experimental specifics i know enough about entanglement/bell's theorem to know the general ideas of what's going on. It's definitely interesting but i'm not ...
2
votes
0answers
19 views

Does the trial index of typical CHSH experiments constitute a “hidden variable”?

In typical experiments related to the CHSH inequality there are individual detections being made by two separate (analyzer-and-)detector systems, "System $A$: $(D_A^+, D_A^-)$" and "System $B$: ...
16
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7answers
3k views

Disproof of Bell’s Theorem

The half-page arxiv doc by Joy Christian of Oxford Uni, UK has the Title and Abstract: Disproof of Bell’s Theorem We illustrate an explicit counterexample to Bell’s theorem by constructing a ...
-1
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1answer
50 views

Question regarding entanglement

Could the paradoxical nature of entanglement be the result of a change in the nature of quantum properties, or an incomplete understanding of such, instead of non-locality?
3
votes
6answers
392 views

How do we know that there isn't a classical solution to the measurement problem/Quantum Mechanical uncertainty?

It was mentioned to me that it can be shown that there is no classical explanation for the uncertainty in Quantum Mechanics -- i.e. that there are no hidden workings that we have just not yet seen, ...
3
votes
1answer
76 views

How are the PPT criterion and Bell's inequality different?

Bell (1964) writes that if we assume an equivalent classical hidden variable distribution for a two-qubit state then the expectation value of the product of two observables $A$ and $B$ can be written ...
0
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0answers
72 views

What does Bell's theorem rule out?

What exactly did Bell's theorem rule out? Did it rule out "locality", so we must give up and think of Copenhagen or maybe some realism theories (Bohmian for example)? ... That's how I understand ...
3
votes
1answer
63 views

Bell inequality with triplet state

Is it possible to prove Bell inequality starting from a state formed from triplet states, i.e. $\frac{1}{\sqrt{2}}(|\uparrow>_A|\uparrow>_B+|\downarrow>_A|\downarrow>_B)$? If not, why? ...
1
vote
0answers
66 views

Realism vs. locality in EPR/Bell arena

I understand that this is a much debated issue, so I will try to be precise in order to narrow the question. Bell inequality violation rules out Local Realism. From this, I understand that by giving ...
3
votes
0answers
52 views

What makes Bell's original inequality unsuitable for experiments?

Bell derives the inequality $$|E(\vec{a},\vec{b})-E(\vec{a},\vec{c})|\leq 1+E(\vec{b},\vec{c})$$ in his book Speakable and unspeakable in quantum mechanics. In this derivation he uses the assumption ...
0
votes
1answer
90 views

Should S always be more than 2 to violate CHSH inequality?

Should the measured value always be about $2\sqrt{2}$ or is it just a maximum value and it is possible to measure something like $S = \{1.90, 1.8, 2.0, 2.4, 2.6, 1.8\}$ (with average equal 2) in ...
31
votes
5answers
4k views

Is Stephen Wolfram's NKS, an attempt to explain the universe with cellular automata, in conflict with Bell's Theorem?

Stephen Wolfram's A New Kind of Science (NKS) hit the bookstores in 2002 with maximum hype. His thesis is that the laws of physics can be generated by various cellular automata--simple programs ...
0
votes
0answers
20 views

I wasn't able to find a good resource for Bipartite state and Bell's theorem

Our professor used tensor product to explain bipartite operator and states and then he used the new operator and state to explain Bell theorem. I wasn't able to find a good resource or reference for ...
4
votes
2answers
143 views

Does Bell's theorem rule out the possiblity that measurements are completely determined by events in the past light cone?

I'm studying Bell's theorem and the CHSH inequality for some time. Now it's clear to me that one cannot reproduce the correlations predicted by quantum mechanics by assuming that particles carry ...
0
votes
1answer
56 views

How does giving up realism preserve locality?

In case I'm going from a wrong assumption here's how I understood the experiment: The singlet electron-positron pair has spin zero, so if we measure one electron as +x (i.e. +1 on x axis) then the ...
1
vote
1answer
57 views

Does the order of detection settings matters in CHSH-inequality check experiment?

Does the order of detection settings matters when checking CHSH inequality? For example, i'm trying to build a simple (and very approximate) computer simulation of experiment. Now i'm testing only ab ...
6
votes
2answers
3k views

Bells Theorem for Dummies, How does it work?

I've been reading up on theoretical physics for a few years now and I feel like I am starting to get an understanding of particle physics, at least as much as you can from Wikipedia pages. One thing ...
2
votes
2answers
71 views

Can the measurement apparatus cause correlations that violate the Bell's inequality?

If you drop a coin it's affected by the air drag, bounces and tumbles on floor before it settles and you can read whether it was heads and tails. If I understood it right, the Bell's theorem says ...
0
votes
3answers
79 views

Does Bell's inequality hold for different particles?

Having read Bell's theorem and proofs. It seems it builds upon the assumption that we measure identical particles. Usually these thought experiments involve giving A and B an identical scratchcard. If ...
3
votes
2answers
131 views

Does Bell's inequalities also rule out non-computable local hidden variable theories?

I have beenn reading different articles on Bell's assumptions and interpretations, including superdeterminsm. I always end up dizzy when I try tho think about this specific question, so any hints ...
0
votes
1answer
59 views

How was phase randomly changing in CHSH test (M. A. Rowe and others)?

Measuring phase of photon should always be random while checking CHSH inequality, but i can't explain this: http://qudev.ethz.ch/content/courses/QSIT08/pdfs/Rowe01.pdf (the most clear experiment i ...
1
vote
1answer
35 views

Restrictions on Bell-type inequalities

While deriving and proving Bell-type inequalities of the form $|E(a,b)-E(a,b')|+|E(a',b)+E(a',b')|\leq 2$ I know that the conditions on the operators $O_a$ and $O_b$ are that they must be bounded ...
2
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2answers
248 views

What are the Implications of Bell's Theorem?

Consider the following game show: two friends Tom and Jerry (X and Y) are selected from an audience to compete for a grand prize, a brand new Ferrari. The game description: The two contestants ...
0
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0answers
69 views

Bell's inequality

For a project, I'm planning to study Bell's inequality, which as far as I can gather is taken to rule out hidden variable theories of QM. I'm looking for recommendations of decent sources which derive ...
0
votes
1answer
230 views

Can Bell's inequality violation be explained by the will of the scientist somehow affecting the experiment?

As far as I know, there are three possible ways to explain violation of Bell's inequality: violation of realism, violation of locality and violation of freedom. The first two are pretty ...
0
votes
1answer
42 views

How much measurements are usually done to test CHSH inequality?

How much times particle is measured during experiment? How much times sub-experiment (state of detector) is randomly changed? Where i can find such statistic?
2
votes
1answer
99 views

Are there any experimental tests of non-locality / Bell inequalities that do not rely on spin?

All the experiments I know, which have been performed to test Bell inequalities, are somehow based on measuring the spin degree-of-freedom of some particle (usually photons, sometimes electrons). I ...
0
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0answers
110 views

The triangle inequality in CHSH derivation, where is the triangle?

http://en.wikipedia.org/wiki/CHSH_inequality#Bell.27s_1971_derivation ... |X + Y| <= |X| + |Y| ??? CHSH inequality is combined from four relative angles between four polarization axis which do ...
1
vote
2answers
104 views

Detection Angles in Bell-type Experiments

Bell-type experiments look at the violation of this inequality: $|S|\leq 2$. where $S=E(a,b)-E(a,b')+E(a',b)+E(a',b')$ and $E$ is the correlation function. Mathematically, the maximal violation of ...
0
votes
3answers
124 views

“Spooky action at a distance” or particle correlation at the time of their creation?

In Bell test experiments, two particles that are a singlet are measured and are found to be correlated. The correlation leads us to believe that they are somehow connected non-locally: the ...
0
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2answers
97 views

Question on the logical structure of the EPR argument and Bell's inequalities

Recently I have read a lot online about the EPR argument and Bell's inequalities and its implications. When comparing what people write there online with the actual research articles of Einstein and ...
2
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2answers
217 views

Why are results of Bell's experiments considered to “break realism”?

Related to my previous question (Why would classical correlation in Bell's experiment be a linear function of angle?), as a newbie in quantum mechanics, I am also unable to find the reason to why ...
3
votes
2answers
390 views

Why isn't the best case classical solution to the CHSH game 100%? [closed]

[Edit 2] I would prefer to just forget that I had ever asked this question (because I was so wrong it's embarrassing), but for the sake of people who possibly make the same mistake I did, I'll try to ...