近日，北京理工大学物理学院的张向东&陈天及其研究团队取得一项新进展。经过不懈努力，他们实现异常点周围的受拓扑保护纠缠切换。相关研究成果已于2024年7月16日在国际知名学术期刊《光：科学与应用》上发表。

本文提出了一种通过设计四重简并异常点来实现量子纠缠态鲁棒操作的有效方案，并通过实验验证了该方案的可行性。研究人员通过将两个重叠黎曼能量面上的异常点环绕起来，实现了高保真纠缠态的手性切换。由于黎曼表面结构所赋予的拓扑保护，这种手性的切换对环绕路径中的扰动具有很强的鲁棒性。

此外，研究人员还在量子行走平台上对该方案进行了实验验证。这项研究工作为非厄米物理在量子信息领域的应用开辟了一条新的途径。

据悉，量子纠缠态的鲁棒性对量子信息、计算和通信的应用至关重要。然而，由于退相干和无序性，完成这一任务一直是一个巨大的挑战。

附：英文原文

Title: Topologically protected entanglement switching around exceptional points

Author: Tang, Zan, Chen, Tian, Tang, Xing, Zhang, Xiangdong

Issue&Volume: 2024-07-16

Abstract: The robust operation of quantum entanglement states is crucial for applications in quantum information, computing, and communications. However, it has always been a great challenge to complete such a task because of decoherence and disorder. Here, we propose theoretically and demonstrate experimentally an effective scheme to realize robust operation of quantum entanglement states by designing quadruple degeneracy exceptional points. By encircling the exceptional points on two overlapping Riemann energy surfaces, we have realized a chiral switch for entangled states with high fidelity. Owing to the topological protection conferred by the Riemann surface structure, this switching of chirality exhibits strong robustness against perturbations in the encircling path. Furthermore, we have experimentally validated such a scheme on a quantum walk platform. Our work opens up a new way for the application of non-Hermitian physics in the field of quantum information.

DOI: 10.1038/s41377-024-01514-1

Source: https://www.nature.com/articles/s41377-024-01514-1