Synchronous observation of Bell nonlocality and state-dependent Kochen-Specker contextuality

Abstract

Bell nonlocality and Kochen-Specker contextuality are two remarkable nonclassical features of quantum theory, related to strong correlations between outcomes of measurements performed on quantum systems. Both phenomena can be witnessed by the violation of certain inequalities, the simplest and most important of which are the Clauser-Horne-Shimony-Holt (CHSH) and the Klyachko-Can-Binicioǧlu-Shumovski (KCBS), for Bell nonlocality and Kochen-Specker contextuality, respectively. It has been shown that, using the most common interpretation of Bell scenarios, quantum systems cannot violate both inequalities concomitantly, thus suggesting a monogamous relation between the two phenomena. In this Letter, we show that the joint consideration of the CHSH and KCBS inequalities naturally calls for the so-called generalized Bell scenarios, which, contrary to the previous results, allows for joint violation of them. A photonic experiment thus tests the synchronous violation of both CHSH and KCBS inequalities. Our results agree with the theoretical predictions, thereby providing experimental proof of the coexistence of Bell nonlocality and Kochen-Specker contextuality in the simplest scenario, and shed new light for further explorations of nonclassical features of quantum systems.

5+6 pages, 3 figures. Comments welcome!

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Cited by in corpus (9)

• Optimal and tight Bell inequalities for state-independent contextuality sets
• Verification of Bell Nonlocality by Violating Quantum Monogamy Relations
• Lifting noncontextuality inequalities
• Harvesting Contextuality from the Vacuum
• The quantum maxima for the basic graphs of exclusivity are not reachable in Bell scenarios
• Trade-off relations between Bell nonlocality and local Kochen-Specker contextuality in generalized Bell scenarios
• States Violating Both Locality and Noncontextuality Inequalities in Quantum Theory
• Probe of Generic Quantum Contextuality and Nonlocal Resources for Qubits
• Bell Meets General Philosophers of Science : Reassessing Measurement Independence