Fully nonlocal quantum correlations

TL;DR

This paper explores the maximal nonlocality of quantum correlations, deriving Bell inequalities from Kochen-Specker proofs, and experimentally demonstrates a Bell test with improved bounds on local content.

Contribution

It introduces a method to derive Bell inequalities from Kochen-Specker proofs that are maximally violated by quantum correlations, and provides experimental bounds on local content.

Findings

Derived Bell inequalities from Kochen-Specker proofs with maximal quantum violation

Experimental Bell test from Peres-Mermin proof bounds local content at p_L ≲ 0.22

Improved bounds on the local content of quantum correlations

Abstract

Quantum mechanics is a nonlocal theory, but not as nonlocal as the no-signalling principle allows. However, there exist quantum correlations that exhibit maximal nonlocality: they are as nonlocal as any non-signalling correlations and thus have a local content, quantified by the fraction $p_L$ of events admitting a local description, equal to zero. Exploiting the link between the Kochen-Specker and Bell's theorems, we derive, from every Kochen-Specker proof, Bell inequalities maximally violated by quantum correlations. We then show that these Bell inequalities lead to experimental bounds on the local content of quantum correlations which are significantly better than those based on other constructions. We perform the experimental demonstration of a Bell test originating from the Peres-Mermin Kochen-Specker proof, providing an upper bound on the local content $p_L\lesssim 0.22$.