Any Physical Theory of Nature Must Be Boundlessly Multipartite Nonlocal

TL;DR

This paper introduces a new class of multipartite nonlocal correlations that cannot be simulated with shared randomness and causal GPT resources, showing quantum states can produce such correlations, implying boundless nonlocality in nature.

Contribution

The paper defines Genuinely LOSR Multipartite Nonlocal correlations and demonstrates that certain quantum states can generate them, indicating that nature's nonlocality is inherently boundlessly multipartite.

Findings

Noisy GHZ states can produce Genuinely LOSR Multipartite Nonlocal correlations.

3-partite W state can produce such correlations.

A computational method certifies this property for an 85% fidelity GHZ state.

Abstract

We introduce the class of Genuinely Local Operation and Shared Randomness (LOSR) Multipartite Nonlocal correlations, that is, correlations between N parties that cannot be obtained from unlimited shared randomness supplemented by any composition of (N-1)-shared causal Generalized-Probabilistic-Theory (GPT) resources. We then show that noisy N-partite GHZ quantum states as well as the 3-partite W quantum state can produce such correlations. This proves, if the operational predictions of quantum theory are correct, that Nature's nonlocality must be boundlessly multipartite in any causal GPT. We develop a computational method which certifies that a noisy N=3 GHZ quantum state with fidelity 85 percent satisfies this property, making an experimental demonstration of our results within reach. We motivate our definition and contrast it with preexisting notions of genuine multipartite nonlocality. This work extends a more compact parallel letter [Phys. Rev. Lett. 127, 200401 (2021)] on the same subject and provides all the required technical proofs.