参量下转换中的高维最大纠缠光子对研究
近日，德国耶拿大学的Richard Bernecker及其研究团队取得一项新进展。经过不懈努力，他们对参量下转换中的高维最大纠缠光子对进行研究。相关研究成果已于2024年9月26日在国际知名学术期刊《物理评论A》上发表。
该研究团队正式阐述了如何同时利用泵浦光束的空间分布和晶体的非线性分布，以在子空间内无需对OAM模式进行额外空间滤波的情况下生成MESs。研究人员以最大纠缠的三态系统（d=3）和五态系统（d=5）为例，说明了他们的方法。
据悉，自发参量下转换产生的光子对是实现纠缠双光子系统的成熟方法。携带轨道角动量（OAM）的拉盖尔-高斯模式通常被用于构建高维纠缠量子态。对于维度d>2的希尔伯特空间，最大纠缠态（MESs）有助于提升量子通信协议的容量和安全性，以及其他多项有前途的特性。然而，在无限OAM基矢的明确定义高维子空间中直接生成MESs仍然是一个挑战。
附：英文原文
Title: High-dimensional maximally entangled photon pairs in parametric down-conversion
Author: Richard Bernecker, Baghdasar Baghdasaryan, Stephan Fritzsche
Issue&Volume: 2024/09/26
Abstract: Photon pairs generated from spontaneous parametric down-conversion are a well-established method to realize entangled bipartite photonic systems. Laguerre-Gaussian modes, which carry orbital angular momentum (OAM), are commonly exploited to engineer high-dimensional entangled quantum states. For Hilbert spaces with dimension d>2, maximally entangled states (MESs) help to improve the capacity and security of quantum communication protocols, among several other promising features. However, the direct generation of MESs in well-defined high-dimensional subspaces of the infinite OAM basis has remained a challenge. Here, we formalize how the spatial distribution of the pump beam and the nonlinear profile of the crystal can be simultaneously utilized to generate MESs without additional spatial filtering of OAM modes within a subspace. We illustrate our approach with maximally entangled qutrits (d=3) and ququints (d=5).
DOI: 10.1103/PhysRevA.110.033718
Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.110.033718
来源：科学网 小柯机器人
