近日，巴西北里奥格兰德联邦大学的Rafael Chaves与西班牙巴塞罗那科学技术学院的Ranieri Nery等人合作并取得一项新进展。经过不懈努力，他们提出观测的干预性贝尔不等式。相关研究成果已于2024年10月21日在国际知名学术期刊《物理评论A》上发表。

在本工作中，研究人员朝这一方向迈出了初步步伐，通过分析工具性场景，提出了结合观测数据和干预数据的混合贝尔不等式。

研究人员聚焦于任意输入数下的二元结果，获得了观测-干预多面体的完整特征描述，这相当于一个类似哈迪的贝尔不等式，尽管它描述的是不同的量子实验。

为了说明其应用，研究人员展示了在量子违背的阈值检测效率方面的显著提升，同时展示了这种混合方法在量子导引场景中的应用。

据悉，目前，人们正通过因果推断的视角来分析贝尔定理的推广，尤其是在量子网络中的应用。然而，对于因果理论中核心概念之一的干预措施的探索，仍然显著不足。

附：英文原文

Title: Observational-interventional Bell inequalities

Author: Davide Poderini, Ranieri Nery, George Moreno, Santiago Zamora, Pedro Lauand, Rafael Chaves

Issue&Volume: 2024/10/21

Abstract: Generalizations of Bell's theorem, particularly within quantum networks, are now being analyzed through the lens of causal inference. However, the exploration of interventions, a central concept in causality theory, remains significantly unexplored. In this work, we take an initial step in this direction, by analyzing the instrumental scenario and proposing hybrid Bell inequalities integrating observational and interventional data. Focusing on binary outcomes with any number of inputs, we obtain the complete characterization of the observational-interventional polytope, equivalent to a Hardy-like Bell inequality, albeit describing a distinct quantum experiment. To illustrate its applications, we show a significant enhancement regarding threshold detection efficiencies for quantum violations also showing the use of this hybrid approach in quantum steering scenarios.

DOI: 10.1103/PhysRevA.110.042213

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.110.042213