Multipartite nonlocality swapping

TL;DR

This paper extends nonlocality swapping to multipartite boxes using a generalized coupler, demonstrating increased efficiency and quantum bounds, with implications for manipulating nonlocality among many users.

Contribution

It introduces a multipartite coupler for nonlocality swapping, generalizing previous bipartite schemes and connecting success probability to Svetlichny inequality.

Findings

Multipartite nonlocality swapping can generate larger nonlocal boxes.

Quantum bounds appear only with noisy boxes involved.

Multipartite coupler enhances efficiency in manipulating nonlocality.

Abstract

Nonlocality swapping of bipartite binary correlated boxes can be realized by a \emph{coupler} ($\chi$) in nonsignaling models. By studying the swapping process we find that the previous bipartite coupler can be applied to the swapping of two multipartite boxes, and then generate a multipartite box with more users than that of any of the boxes before swapping. Here quantum bound still appears in the scheme. The bipartite coupler also can be applied to a hybrid scheme of generating a multipartite extremal box from many PR boxes. As the analogue of multipartite entanglement swapping, we generalize the nonlocality swapping of bipartite binary boxes to multipartite binary boxes by using a multipartite coupler $\chi_{N}$, and get the probability of success by connecting the coupler to the generalized Svetlichny inequality. The multipartite coupler acting on many multipartite boxes makes multipartite nonlocality swapping be a more efficient device to manipulate nonlocality between many users. The results show that Tsirelson's bound for quantum nonlocality emerges only when two of the $n$ boxes involved in the coupler process are noisy ones.