近日，山西大学的苏晓龙及其研究团队取得一项新进展。经过不懈努力，他们基于光子减法实现连续变量纠缠交换。相关研究成果已于2024年7月3日在国际知名学术期刊《物理评论A》上发表。

本文提出了一种在噪声信道中通过光子减法(PS)操作增强CV纠缠交换纠缠的方案。研究人员分别通过有损单通道和双通道传输方案在CV纠缠交换中应用了单侧和双侧PS操作。在有损信道中，研究人员证明了与单侧PS操作相比，双侧PS操作可以获得更高的纠缠和更长的传输距离。

此外，研究人员还证明了在含噪单通道CV纠缠交换中，双侧PS操作可以增强纠缠交换的纠缠性。这项研究结果提供了一种增强CV纠缠交换纠缠度的可行解决方案来，并且在构建量子中继器中具有潜在的应用前景。

据悉，在基于纠缠的量子网络中，纠缠交换是量子中继器的关键组成部分，它在两个独立且遥远的纠缠态之间建立纠缠。在连续变量(CV)纠缠交换中，纠缠交换的纠缠度随着量子信道中的损耗和噪声而减小，因此提高纠缠度至关重要。

附：英文原文

Title: Continuous-variable entanglement swapping with photon subtraction

Author: Na Wang, Meihong Wang, Xiaolong Su

Issue&Volume: 2024/07/03

Abstract: Entanglement swapping, which establishes entanglement between two independent and distant entangled states, is a key element of a quantum repeater in an entanglement-based quantum network. In continuous-variable (CV) entanglement swapping, it is essential to enhance the entanglement of entanglement swapping because it decreases with loss and noise in the quantum channel. Here, we propose a scheme of enhancing entanglement of CV entanglement swapping by a photon subtraction (PS) operation in noisy channels. We apply both one- and two-sided PS operations in CV entanglement swapping through lossy single- and dual-channel transmission schemes, respectively. In the lossy channel, we show that the two-sided PS operation enables one to obtain higher entanglement and longer transmission distance compared to the one-sided PS operation. Furthermore, we show that the two-sided PS operation can enhance the entanglement of the entanglement swapping in the noisy single-channel CV entanglement swapping. Our results provide a feasible solution to enhance entanglement of CV entanglement swapping, and they have potential applications in building quantum repeaters.

DOI: 10.1103/PhysRevA.110.012416

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.110.012416