Physics Stack Exchange
Physics Stack Exchange

Questions tagged [bells-inequality]

Bell's inequality is a no-go theorem contrasting crucial correlations of physical observables in QM to those of the world as described by classical mechanics, essentially local hidden variables theories serving as a viable "explanation" of QM: QM inevitably violates these inequalities, as observed. Further use for the CHSH inequality generalization.

Bell's inequality is a no-go theorem contrasting crucial correlations of physical observables in QM to those of the world as described by classical mechanics, essentially local hidden variables theories serving as a viable "explanation" of QM: QM ineluctably violates these inequalities, as observed. Further use for the CHSH inequality generalization (by J Clauser, M Horne, A Shimony and R Holt).

363 questions
4
votes
1 answer

Simplified Derivation of CHSH/Bell inequalities

Preamble Back in the day when I was still studying, I visited a very interesting lecture by a young professor that focused on the intersection between physics and computer science, with some modules about computability, computational complexity, and…
carsten
  • 153
2
votes
1 answer

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 article, at page 196. I don't understand what is the reasoning that leads to this…
mwoua
  • 243
1
vote
1 answer

I'm missing something basic in understanding Bell's theorem

I've read the wikipedia article, but I'm lacking some very basic understanding of entanglement probably. If I understand correctly, the experiment that is repeated is not time dependent, right? e.g. my understanding is this: Alice and Bob are far…
Eran Medan
  • 177
1
vote
1 answer

How do loophole-free Bell’s inequality violation tests rule out conspiracy via signals that have to travel back to the experimenter?

First, I’d like to apologize for yet another question about crazy ideas on how quantum mechanics might actually work. I have no background in quantum mechanics. Recently, though, I started to study quantum computing, which turned my attention to…
Dmitri Urbanowicz
  • 141
1
vote
2 answers

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 the inequality is reached when $|S|=4$ (because the…
user3625380
  • 103
1
vote
4 answers

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 are space-like separated. Each contestant will be…
user7348
  • 1,096
0
votes
1 answer

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 $$\left|P(a,b)-P(a,b')\right|+P(a',b)+P(a',b')\leq 2 \tag{1}$$ while the…
mwoua
  • 243
0
votes
1 answer

John Bell's formulation of the Bell Inequality

In "ON THE EINSTEIN-PODOLSKI-ROSEN PARADOX" by Bell(1964), Eq(14)…
정수영
  • 13
0
votes
1 answer

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) to violate the CHSH inequality? EDIT: By $S$ I mean $S$…
dk14
  • 145
0
votes
0 answers

What does Bell's Theorem really violate?

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 exactly does it violate. I am just a bit…
rahulgarg12342
  • 2,469