Progress towards Bell-type polarization experiment with thermal neutrons

TL;DR

This paper reports the first Bell-type experiment with thermal neutron pairs, confirming quantum predictions and advancing tests of quantum nonlocality and noncontextuality with massive particles.

Contribution

It presents the first experimental Bell-type test using thermal neutrons, extending quantum nonlocality tests to massive particles.

Findings

Confirmed quantum-theoretical predictions with neutron pairs

Demonstrated Bell inequality violation with thermal neutrons

Extended the scope of Bell tests beyond photons

Abstract

Experimental tests of Bell-type inequalities distinguishing between quantum mechanics and local realistic theories remain of considerable interest if performed on massive particles, for which no conclusive result has yet been obtained. Only two-particle experiments may specifically test the concept of spatial nonlocality in quantum theory, whereas single-particle experiments may generally test the concept of quantum noncontextuality. Here we have performed the first Bell-type experiment with a beam of thermal-neutron pairs in the singlet state of spin, as originally suggested by J. S. Bell. These measurements confirm the quantum-theoretical predictions, in agreement with the results of the well-known polarization experiments carried out on optical photons years ago.