The discussion revolves around the maximal violations of Bell's inequalities in quantum experiments, specifically focusing on both recorded experimental results and theoretical limits. Participants explore the implications of these violations, the definitions of "ideal" experiments, and the relevance of Tsirelson's bound.
Participants express uncertainty regarding the maximum level of violation, with some suggesting that 2.42 may not be the ultimate limit and others referencing theoretical bounds. Multiple competing views on the definitions of "ideal" experiments and the implications of Tsirelson's bound remain unresolved.
The discussion includes references to specific experiments and theoretical constructs, but lacks consensus on the maximum recorded violations and the implications of Tsirelson's bound in various contexts.
I mean it in the sense that as many loopholes are closed as possible.Nugatory said: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?
This one, from 2015: https://arxiv.org/abs/1508.05949 was discussed in several threads here when it first appeared.john taylor said:I mean it in the sense that as many loopholes are closed as possible.
So is 2.42 the maximum level of violation ?Nugatory said: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 said:So is 2.42 the maximum level of violation ?
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?atyy said: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/