Experimental observation of quantum state-independent contextuality under no-signaling conditions

Abstract

Contextuality, the impossibility of assigning context-independent measurement outcomes, is a critical resource for quantum computation and communication. No-signaling betweensuccessivemeasurementsisanessentialrequirementthatshouldbeaccomplishedin anytestofquantumcontextualityandthatisdifficulttoachieveinpractice.Here,weintroduce anoptimalquantumstate-independentcontextualityinequalityinwhichthedeviationfromthe classicalboundismaximal.Wethenexperimentallytestitusingsinglephotonsgeneratedfrom a defect in a bulk silicon carbide, while satisfying the requirement of no-signaling within the experimental error. Our results shed new light on the study of quantum contextuality under no-signalingconditions.