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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 ...
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68 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 ...
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52 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 ...
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1answer
160 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 ...
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51 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 ...
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33 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?
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96 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 ...
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53 views

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

Is it always should be about $2\sqrt{2}$ or it's just a maximum value and it's possible to measure something like S = 1.90, 1.8, 2.0, 2.4, 2.6, 1.8 (with average = 2) in different sub-experiments to ...
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1answer
71 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 ...
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1answer
48 views

Does it matter in which order settings will be changed during CHSH-inequality check experiment?

Does it matter in which order detector settings will be changed when checking CHSH inequality? For example, i'm trying to build a simple (and very approximate) computer simulation of experiment. Now ...
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60 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 ...
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2answers
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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 ...
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73 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 ...
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2answers
159 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 ...
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106 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 ...
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0answers
64 views

Is there a cheap way I can do a Bell inequality experiment?

My work is almost completely theoretical/computational. But I'd really like to do a Bell inequality experiment just so I can personally see this (the best way to learn something is hands-on, right?) ...
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2answers
237 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 ...
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2answers
186 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 ...
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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 ...
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449 views

Why was quantum mechanics regarded as a non-deterministic theory?

It seems to be a wide impression that quantum mechanics is not deterministic, e.g. the world is quantum-mechanical and not deterministic. I have a basic question about quantum mechanics itself. A ...
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1answer
500 views

Why can't I use Bell's Theorem for faster than light communication?

I read this description of Bell's theorem. I understand he's restating it slightly, so there may be incorrect assumptions there, or I may have some. I think Bell's theorem should lead to FTL ...
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2answers
306 views

Determinism loophole?

I was thinking about the question I posted yesterday, and I thought of a better way to ask it. I'm trying to figure out why QM necessitates "pure randomness". Assume you have a photon that has a ...
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40 views

What does Bell's Theorem really violate? [duplicate]

Well this is a fairly straightforward question. I know it states that either hidden variables is wrong or Quantum Mechanics. But indirectly hidden variables is a part of QM due to uncertainty. So what ...
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3answers
110 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 ...
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1answer
143 views

(thought) experiment re: Bell's Theorem and Schrodinger's cat

I apologize if this question is naive. I am wondering about what would happen with the following experiment. Start with a standard Bell's Theorem setup: We have two quibits entangled in a particular ...
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138 views

Has Bell really demonstrated that no local hidden variable theory can exist in his original paper of 1964? Why then verify the CHSH violation?

The more I read about it and the more I'm convinced I haven't understood what I thought I had. In the original paper ...
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42 views

Where does the CSHS inequality really come from

I'm reading about Bell's inequalities and hidden variables theory. And I wonder where does the CSHS inequality really come from ? I read the paper and the inequality we find is ...
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1answer
79 views

Question on expression in “J.S.Bell : On the Einstein Podolsky Rosen paradox”

I have a question on the article J. S. Bell, On the Einstein Podolsky Rosen paradox, Physics 1, 195, 1964. (link) My question concerns the expression (3) of the ...
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2answers
159 views

Non-locality and Bell's theory

Non-Locality – (just ) one more question? I have read comments that Bell’s theory proves quantum mechanics is non-local, and also comments that it does not. I have read a comment by a very eminent ...
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2answers
537 views

Pauli matrices as measurement operators

I am trying to understand a paper on the Bell test experiments. I understand that if we wanted to measure the spin of a spin-1/2 particle in state $\psi$ along the z-axis we would apply the operator ...
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2answers
197 views

On Bell inequality and bound entangled states

I have recently seen some presentation slides of Michał Horodecki (slide number 77) in which he discussed the following conjecture. Bound entangled states satisfy all Bell inequalities The ...
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1answer
344 views

Measuring Entangled Qubits

Suppose we have a pair of entangled qubits. $$ |\psi\rangle = \frac{1}{ \sqrt{2} } ( |00\rangle + |11\rangle ) $$ Now we give one qubit to Alice and other to Bob. Alice measure the her qubit to ...
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76 views

Why Quantum correlation is not uniform in this diagram?

Following diagram is from a Wikipedia article which shows Quantum Correlation for local hidden variables and Quantum Mechanics and experiments confirm Quantum Mechanics predictions. My question is ...
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1answer
73 views

Is it possible to determine the state or values of something without measuring it

To give context to this question, I am currently looking into non-locality / hidden variables / Bell's Theorem, EPR / etc. I've noticed the assertion that the values / state of something when ...
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5answers
318 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, ...
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222 views

Bell's Theorem graph

My friends and I got into an argument about determinism, and I brought up that quantum events are random. But I couldn't prove it. I found the Wikipedia page on Bell's theorem, which seems to imply ...
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128 views

EPR vs. EPRBB? Why can't we perform the original EPR experiment?

The EPR gedanken experiment was invented by Einstein Podolsky and Rosen in 1935. It involved positions and momenta. In 1957, Bohm revised this gedanken experiment into one involving spins, or ...
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4answers
550 views

How do we show that no hidden variable theories can replace QM?

I've always hit two big stumbling blocks in conceiving of the proof or disproof of hidden variable theories as being even valid idea, let alone an answerable question... I feel I must be ...
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2answers
359 views

What are the “loopholes” in past Bell's theorem experiments?

I am intrigued by the following Phys.org article: Researchers began using photons in 1980s to test Bell's theory and determine if Einstein's reasoning is right or wrong. Since then, researchers ...
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How does Bell's theorem rule out the possibility of local hidden variables?

It seems to be common consensus that the world is non-deterministic and this is proved by Bell's theorem. But even though Bell's experiments proved that the theory of quantum mechanics work, How does ...
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366 views

Does this Bell's experiment actually disprove Local Hidden Variable Theories (LHVT)

I'm watching some archived video lectures on QM in Coursera given by Umesh Vazirani from UC Berkeley and I have a question regarding a Bell's experiment (I guess something close to this) described in ...
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208 views

Generalizations of Bell's inequality to quantum field theory

Can anyone refer me to some sources on generalizations of Bell's inequalities to quantum field theory (as opposed to quantum mechanics)? Scalar fields would be enough.
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79 views

Photon source for Bell test

Wiki tells us that In practice most actual experiments have used light, assumed to be emitted in the form of particle-like photons (produced by atomic cascade or spontaneous parametric down ...
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388 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 ...
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Interpretation of “superqubits”

Two very intriguing papers recently appeared on the arXiv, claiming that one can use "superqubits" -- a supersymmetric generalization of qubits -- to violate the Bell inequality by more than standard ...
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1answer
606 views

Why does quantum mechanics invalidate one of locality and realism?

I am approaching this from an intuitive perspective and I don't speak the language. However, I have been doing a lot of reading about Bell's Theorum and how invalidates either locality or ...
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90 views

Would Einstein have accepted the presumptions that lead to the Bell inequality?

To check the correlation between Hidden Variable Theory and Quantum Mechanics, Bell calculated the expectation value $<\sigma_{e}(\vec a,\vec V) \sigma_{p}(\vec b,\vec V)> = \int d^n V ...
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216 views

On Bell's Inequality (Classical Intuition) and Quantum Mechanical Counter Intuition

This posting is directly related to the issue in The System and the Measuring Gadget. The QM expectation is given by: $$\langle\sigma_{1}.\vec{a}{\;}\sigma_{2}.\vec b\rangle=-\vec a.\vec b$$ In the ...
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381 views

Show quantum entanglement to a classical thinker

Can someone describe a simple experiment to convince a person thinking about physics classically (called Claus) that quantum mechanics has something weird, entangled? I mean an experiment that he ...
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224 views

What exactly does $S$ represent in the CHSH inequality $-2\leq S\leq 2$?

What exactly does $S$ represent in the CHSH inequality $$-2~~\leq ~S~\leq ~2?$$ Sorry I've been reading for a couple days and I can't figure out what exactly $S$ is and the math is a bit over my ...