日本庆应义塾大学Masahiro Takeoka研究团队在最新研究中，报道了基于局部测量的多部单光子纠缠量子态估计。相关论文发表在2025年2月18日出版的《物理评论A》杂志上。

据了解，多部纠缠在量子互联网的各种应用中起着至关重要的作用。在这些应用中，纠缠通常由遥远的各方共享。在实验中，分布式纠缠只能通过局部测量来估计。此外，对于网络实验，最好采用易于实现的测量技术。

本文提出了一种仅通过局部量测测量任意多部单光子路径纠缠态的方法。通过考虑实际合理的假设，这一方法相对容易实现。该课题组通过重建3量子位W态的密度矩阵，实验证明了该方法的实用性。

附：英文原文

Title: Quantum state estimation of multipartite single-photon path entanglement via local measurements

Author: Hikaru Shimizu, Joe Yoshimoto, Kazufumi Tanji, Aruto Hosaka, Junko Ishi-Hayase, Tomoyuki Horikiri, Rikizo Ikuta, Masahiro Takeoka

Issue&Volume: 2025/02/18

Abstract: Multipartite entanglement plays a critical role in various applications of quantum internet. In these applications, the entanglement is usually shared by the distant parties. Experimentally, the distributed entanglement should be estimated by only local measurements. Furthermore, for network experiments, it is desirable to employ measurement techniques that are straightforward to implement. In this paper, we propose a method to measure arbitrary multipartite single-photon path entangled states by only local measurements. By considering practically reasonable assumptions, our method is relatively easy to implement. We experimentally demonstrate the utility of this method by reconstructing the density matrix of a 3-qubit W state.

DOI: 10.1103/PhysRevA.111.022619

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.111.022619