Confined Contextuality in Neutron Interferometry: Observing the Quantum Pigeonhole Effect

Abstract

Previous experimental tests of quantum contextuality based on the Bell-Kochen-Specker (BKS) theorem have demonstrated that not all observables among a given set can be assigned noncontextual eigenvalue predictions, but have never identified which specific observables must fail such assignment. We now remedy this shortcoming by showing that BKS contextuality can be confined to particular observables by pre- and postselection, resulting in anomalous weak values that we measure using modern neutron interferometry. We construct a confined contextuality witness from weak values, which we measure experimentally to obtain a $5\sigma$ average violation of the noncontextual bound, with one contributing term violating an independent bound by more than $99\sigma$. This weakly measured confined BKS contextuality also confirms the quantum pigeonhole effect, wherein eigenvalue assignments to contextual observables apparently violate the classical pigeonhole principle.

8 pages, 7 figures

References in corpus (8)

• State-independent experimental test of quantum contextuality
• Experimental test of quantum contextuality in neutron interferometry
• Anomalous Weak Values Are Proofs of Contextuality
• Preparation contextuality powers parity-oblivious multiplexing
• Strong Kochen-Specker theorem and incomputability of quantum randomness
• Experimental implementation of a Kochen-Specker set of quantum tests
• Experimental demonstration of direct path state characterization by strongly measuring weak values in a matter-wave interferometer
• Pre- and Post-selection paradoxes and contextuality in quantum mechanics

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