Maximum violation of Bell's Inequalities?

[john taylor]

Can someone please tell me(and in simple terms-like in percentages), what the maximal violations of Bell's inequality has been recorded at in actual experiments and in an ideal scenario? Thank you.

 

[Nugatory]

One clarification: By "ideal", do you mean an experiment that most closely resembles the idealized model Bell analyzed in his original paper (two spin-1/2 particles in the singlet state) or those experiments that most effectively close as many loopholes as possible?

 

[john taylor]

One clarification: By "ideal", do you mean an experiment that most closely resembles the idealized model Bell analyzed in his original paper (two spin-1/2 particles in the singlet state) or those experiments that most effectively close as many loopholes as possible?

I mean it in the sense that as many loopholes are closed as possible.

 

[Nugatory]

I mean it in the sense that as many loopholes are closed as possible.

This one, from 2015: https://arxiv.org/abs/1508.05949 was discussed in several threads here when it first appeared.
Using the CHSH form of the inequality, 2.42 against the classical limit of 2.0

(the link is to a preprint -as far as I know the final publication is behind a paywall)

 

[john taylor]

This one, from 2015: https://arxiv.org/abs/1508.05949 was discussed in several threads here when it first appeared.
Using the CHSH form of the inequality, 2.42 against the classical limit of 2.0

(the link is to a preprint -as far as I know the final publication is behind a paywall)

So is 2.42 the maximum level of violation ?

 

[atyy]

So is 2.42 the maximum level of violation ?

The theoretical maximum possible in quantum theory in that situation is given by Tsirelson's bound.
https://en.wikipedia.org/wiki/Tsirelson's_bound

The theoretical maximum possible in quantum theory in other situations has interesting issues including Tsirelson's problem, which is related to MIP* = RE, on which progress seems to have been made recently.
https://en.wikipedia.org/wiki/Tsirelson's_bound#Tsirelson's_problem
https://quantumfrontiers.com/2020/03/01/the-shape-of-mip-re/

 

[john taylor]

The theoretical maximum possible in quantum theory in that situation is given by Tsirelson's bound.
https://en.wikipedia.org/wiki/Tsirelson's_bound

The theoretical maximum possible in quantum theory in other situations has interesting issues including Tsirelson's problem, which is related to MIP* = RE, on which progress seems to have been made recently.
https://en.wikipedia.org/wiki/Tsirelson's_bound#Tsirelson's_problem
https://quantumfrontiers.com/2020/03/01/the-shape-of-mip-re/

For CHSH how large is the violation given by Tsirelson's bound? So by what margin would it theoretically be larger than 2 according to this bound?

 

[Nugatory]

For CHSH how large is the violation given by Tsirelson's bound? So by what margin would it theoretically be larger than 2 according to this bound?

It’s just about the first thing in the Wikipedia article @atyy linked: $2\sqrt{2}$.