Redefining Genuine Multi-Party Nonlocality for Quantum Networks

量子非定域性是一个令人着迷的现象。为了观察它，人们需要在两个或多个可能相隔很远的位置同时测量先前纠缠在一起的微小量子粒子，比如光子。这些测量揭示了无法用粒子的任何可能的局部预先存在的特性来解释的模式——粒子似乎以一种随机的、但立即协调的方式对测量做出反应。虽然量子非局部性对两个纠缠粒子的两个独立位置的测量有很好的理解，但对多个纠缠粒子的三个或更多的分离测量却知之甚少。这个项目的工作是更好地理解这种多粒子设置下的量子非定域性——它在哪些方面与双位置变体有根本的不同？除了建立我们对这一迷人现象的理解之外，这项工作对量子通信和密码协议具有重要意义。量子网络的新操作视角最近促成了令人信服的重新定义，即哪些类型的非局域效应应该被认为是真正的多部非局域效应——也就是说，哪些类型的效应从根本上超越了非局域的两位置形式。本项目旨在精确地描述实验统计的模式，这些模式与真正的多部非定域性的各种新定义一致，并改进满足其中一种定义而不满足另一种定义的现象的解释。这将导致更好地理解潜在的实验，可以展示各种形式的真正的多部非定域性。这些新知识将应用于量子信息协议，如向多方分发秘密密码密钥，分析真正的多方非定域性的新定义如何与此类任务的保密性和有效性相关。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Quantum nonlocality is a fascinating phenomenon. To observe it, one makes simultaneous measurements at two or more locations, potentially separated by a great distance, of tiny quantum particles such as photons that have been previously entangled. These measurements reveal patterns that cannot be explained by any possible local pre-existing properties of the particles – the particles appear to be responding to the measurements in a random, but instantly coordinated, manner. And while quantum nonlocality is reasonably well understood for measurements at two separate locations of two entangled particles, it is less well understood for three or more separated measurements of multiple entangled particles. The work of this project is to better understand quantum nonlocality in this multiple-particle setting – in what ways is it fundamentally different from the two-location variant? In addition to building our understanding of this fascinating phenomenon, this work has significance for quantum communication and cryptography protocols.New operational perspectives on quantum networks have recently contributed to compelling redefinitions of what types of nonlocal effects should be considered genuinely multipartite nonlocal – that is, what types of effects transcend the two-location form of nonlocality in a fundamental manner. This project aims to precisely characterize the patterns of experimental statistics that are consistent with each of these various new definitions of genuine multipartite nonlocality, and to refine interpretations of the phenomena that satisfy one of these definitions but not another. This will lead to a better understanding of potential experiments that could exhibit the various forms of genuine multipartite nonlocality. This new knowledge will be applied to quantum information protocols such as the distribution of secret cryptographic key to multiple parties, analyzing how the new definitions of genuine multi-party nonlocality relate to the secrecy and effectiveness of such tasks.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.