Experimental Test of Quantum Contextuality in Neutron Interferometry

Abstract

We performed an experimental test of the Kochen-Specker theorem based on an inequality derived from the Peres-Mermin proof, using spin-path (momentum) entanglement in a single neutron system. Following the strategy proposed by Cabello et al. [Phys. Rev. Lett. 100, 130404 (2008)10.1103/PhysRevLett.100.130404], a Bell-like state was generated, and three expectation values were determined. The observed violation 2.291 +/- 0.008 not less, dbl equals1 clearly shows that quantum mechanical predictions cannot be reproduced by noncontextual hidden-variable theories.

Event‐by‐event simulation of quantum phenomena

“…4) yields S max ≡ S(α = 0, χ = π/4, α = π/2, χ = π/4) = 2.05, in excellent agreement with the value 2.052±0.010 obtained in experiment [38]. For γ = 0.67 the simulation yields S max = 2.30, in excellent agreement with the value 2.291 ± 0.008 obtained in a similar, more recent experiment [75].…”

Bell’s Universe: A Personal Recollection

“…Finally, I also want to refer to Bell inequality tests of the group of Helmut Rauch [173][174][175]. These neutron interferometer experiments were of particular interest since in this case the quantum correlations were explored in the degrees of freedom of a single particle, the neutron.…”

Proposed test of macroscopic quantum contextuality

“…So far, it has only been observed in two-qubit systems: pairs of ions with two internal levels [6], polarization and path of single photons [7], and two-qubit nuclear magnetic resonance systems [8]. Related quantum contextuality experiments for specific states have been performed using also two-qubit systems: spin and path of single neutrons [9], and polarization of two-photon systems [10]. A natural question is whether SIQC can be observed in larger physical systems.…”