近日，山西大学的苏晓龙&李淑静及其研究团队取得一项新进展。经过不懈努力，他们成功制备了携带轨道角动量的混合纠缠。相关研究成果已于2025年1月7日在《科学通报》上发表。

该研究团队证实携带轨道角动量（OAM）的混合纠缠的实验制备，该纠缠涉及极化、猫态和轨道角动量三个自由度。通过使用q板转换光学猫态的波前，研究人员将轨道角动量自由度引入到，极化编码的离散变量量子比特和猫态编码的连续变量量子比特之间制备的混合纠缠中。

基于测量的拓扑荷l = 0、+1、+2以及输出态的重建维格纳函数，研究人员确认了携带l = 0、+1、+2轨道角动量的混合纠缠态，它们分别具有非零的对数负值度。这项研究工作为扩展混合纠缠的自由度迈出了关键一步，为混合量子信息处理提供了新的量子资源。

据悉，混合连续变量（CV）和离散变量（DV）纠缠是混合量子信息处理中不可或缺的量子资源，它使人们能够克服连续变量和离散变量量子协议的内在局限性。除了连续变量和离散变量量子态之外，引入更多自由度是增加纠缠态所携带信息的一种可行方法。在光子的所有自由度中，轨道角动量（OAM）在增强量子通信容量和提高量子测量精度方面具有潜在应用价值。

附：英文原文

Title: Hybrid entanglement carrying orbital angular momentum

Author: Shujing Li a b, Xiaolong Su a b

Issue&Volume: 2025/01/07

Abstract: Hybrid continuous-variable (CV) and discrete-variable (DV) entanglement are essential quantum resource of hybrid quantum information processing, which enables one to overcome the intrinsic limitations of CV and DV quantum protocols. Besides CV and DV quantum variables, introducing more degrees of freedom provides a feasible approach to increase the information carried by the entangled state. Among all the degrees of freedom of photons, orbital angular momentum (OAM) has potential applications in enhancing the communication capacity of quantum communication and precision of quantum measurement. Here, we present the experimental preparation of hybrid entanglement carrying OAM, which involves three degrees of freedom including polarization, cat states, and OAM. By converting the wavefront of optical cat states with a q-plate, the OAM degree of freedom is introduced into the prepared hybrid entanglement between a polarization-encoded DV qubit and a cat-encoded CV qubit. Based on the measured topological charges l = 0, +1, +2 and reconstructed Wigner functions of the output states, the hybrid entangled states carrying OAM with l = 0, +1, +2 are confirmed with non-zero logarithmic negativities, respectively. Our work takes a crucial step towards extending the degree of freedom for hybrid entanglement, which provides a new quantum resource for hybrid quantum information processing.

DOI: 10.1016/j.scib.2025.01.003

Source: https://www.sciencedirect.com/science/article/pii/S2095927325000052