Engineering of triply entangled states in a single-neutron system

TL;DR

This paper demonstrates the creation and manipulation of a triply entangled GHZ-like state in a single neutron, providing experimental evidence of quantum contextuality through violation of a Mermin inequality.

Contribution

It reports the first implementation of a triply entangled GHZ-like state in a single neutron system with coherent control over multiple degrees of freedom.

Findings

Violation of Mermin inequality with M=2.558, confirming quantum contextuality.

Successful manipulation of spin, path, and energy degrees of freedom in a neutron.

Experimental validation of tripartite entanglement in a single-particle system.

Abstract

We implemented a triply entangled Greenberger-Horne-Zeilinger(GHZ)-like state and coherently manipulated the spin, path, and energy degrees of freedom in a single neutron system. The GHZ-like state was analyzed with an inequality derived by Mermin: we determined the four expectation values and finally obtained M = 2.558 +/- 0.004 > 2, which exhibits a clear violation of the noncontextual assumption and confirms quantum contextuality.