Nonlocality Distillation for High-Dimensional System

TL;DR

This paper develops universal distillation protocols for high-dimensional nonlocality in bipartite systems, demonstrating that nonlocality can be amplified beyond binary systems and that class differences affect distillation efficiency.

Contribution

It introduces comparators-based protocols for high-dimensional nonlocality distillation, extending previous binary protocols to any dimension and highlighting the importance of class-based nonlocality representations.

Findings

High-dimensional nonlocality can be distilled using new protocols.

Efficiency depends on wiring and class of initial nonlocality boxes.

Protocols are more powerful and universal than previous two-dimensional methods.

Abstract

The intriguing and powerful capability of nonlocality in communication field ignites the research of the nonlocality distillation. The first protocol presented in Ref[Phys. Rev. Lett. 102, 120401] shows that the nonlocality of bipartite binary-input and binary-output nonsignaling correlated boxes could be amplified by 'wiring' two copies of weaker-nonlocality boxes. Several optimized distillation protocols were presented later for bipartite binary-input and binary-output nonsignaling correlated boxes. In this paper, we focus on the bipartite binary-input and multi-nary-output nonsignaling correlated boxes---high-dimensional boxes, and design comparators-based protocols to achieve the distillation of high-dimensional nonlocality. The results show that the high-dimensional nonlocality can be distilled in different ways, and we find that the efficiencies of the protocols are influenced not only by the wirings but also by the classes the initial nonlocality boxes belongs to. Here, the initial nonlcalities may have the same violation of the high-dimensional Bell-type inequality, but they can fall into different classes, which shows that the value of the violation of the high-dimensional Bell-type inequality is not the only representation of nonlocality, and the combination manner(classes) in the expression of the correlated boxes is another important nonlocal representation too. The current protocols are compatible with the previous two-dimensional nonlocality distillation protocols, but our protocols are more powerful and universal than previous ones in the sense that the current protocols can be applied to the system with any dimension rather than the only two-dimension system in the previous protocols.