Genuinely multipartite entangled quantum states with fully local hidden variable models and hidden multipartite nonlocality

TL;DR

This paper demonstrates that certain genuinely multipartite entangled quantum states can have fully local hidden variable models, yet their nonlocality can be activated through measurement sequences, revealing hidden nonlocality.

Contribution

It introduces the existence of genuinely multipartite entangled states with fully local models and shows how their nonlocality can be activated, advancing understanding of entanglement and nonlocality.

Findings

Existence of multipartite entangled states with local hidden variable models.

Activation of hidden nonlocality via measurement sequences.

Nonlocality can be revealed even when Bell inequalities are not initially violated.

Abstract

The relation between entanglement and nonlocality is discussed in the case of multipartite quantum systems. We show that, for any number of parties, there exist genuinely multipartite entangled states which admit a fully local hidden variable model, i.e. where all parties are separated. Hence, although these states are entangled in the strongest possible sense, they cannot lead to Bell inequality violation considering general non-sequential local measurements. Then, we show that the nonlocality of these states can nevertheless be activated using sequences of local measurements, thus revealing genuine multipartite hidden nonlocality.