Genuine multipartite nonlocality in the one-dimensional ferromagnetic spin-1/2 chain

TL;DR

This paper demonstrates the existence of genuine multipartite nonlocality in a one-dimensional ferromagnetic spin-1/2 chain using Bell-type inequalities and explores its relationship with multipartite entanglement.

Contribution

The study introduces a method to detect genuine multipartite nonlocality in a spin chain and provides the first evidence of such nonlocality in this system.

Findings

Multiple violations of Bell-type inequality were observed.

Genuine multipartite nonlocality exists in the ferromagnetic spin-1/2 chain.

The relationship between nonlocality and entanglement was analyzed.

Abstract

Genuine multipartite entanglement has been found in some spin chain systems. However, genuine multipartite nonlocality, which is much rarer than genuine multipartite entanglement, has never been found in any spin chain system. Here we present genuine multipartite nonlocality in a spin chain system. After introducing the definition of genuine multipartite nonlocality and a multipartite Bell-type inequality, we construct a group of joint measurements for the inequality in a one-dimensional ferromagnetic $N$-qubit chain with nearest-neighbor XXZ interaction, and many violations to the inequality have been found. The violations do indicate that genuine multipartite nonlocality exists in this ferromagnetic spin-1/2 chain system. Last but not least, we also calculate genuine multipartite entanglement concurrence in the same spin chain to demonstrate the difference and relationship between genuine multipartite nonlocality and genuine multipartite entanglement.