近日，韩国科学技术研究院的Yong-Su Kim&Wan Zo及其研究团队取得一项新进展。经过不懈努力，他们利用光子数编码态经由损耗通道实现纠缠交换。相关研究成果已于2024年11月5日在国际知名学术期刊《物理评论A》上发表。

在这项工作中，研究人员从理论和实验上研究了一种使用光子数编码态的纠缠交换协议，该协议无需光子量子存储器即可有效减轻量子通道的损耗。研究人员证明该协议的成功概率与通道透射率成线性关系。

此外，他们还表明，虽然不平衡的通道损耗会降低共享纠缠的质量，但可以通过优化调整初始纠缠态来补偿这一影响。这项研究结果凸显了光子数编码在实现有损量子网络中稳健纠缠分发的潜力。

据悉，在量子网络中，远距离双方之间的纠缠是一种关键资源。然而，量子通道中的光子损失会显著降低纠缠共享的成功概率，该概率与通道透射率成二次方关系下降。虽然利用纠缠交换的量子中继器可以缓解这一问题，但通常需要高性能的光子量子存储器来同步光子量子比特。

附：英文原文

Title: Entanglement swapping via lossy channels using photon-number-encoded states

Author: Wan Zo, Bohdan Bilash, Donghwa Lee, Yosep Kim, Hyang-Tag Lim, Kyunghwan Oh, Syed M. Assad, Yong-Su Kim

Issue&Volume: 2024/11/05

Abstract: Entanglement between distant parties is a key resource in quantum networks. However, photon losses in quantum channels significantly reduce the success probability of entanglement sharing, which scales quadratically with the channel transmittivity. Quantum repeaters using entanglement swapping can mitigate this effect, but usually require high-performance photonic quantum memories to synchronize photonic qubits. In this work, we theoretically and experimentally investigate an entanglement swapping protocol using photon-number-encoded states that can effectively alleviate quantum channel losses without requiring photonic quantum memories. We demonstrate that the protocol exhibits a success probability scaling linearly with the channel transmittivity. Furthermore, we show that while unbalanced channel losses can degrade the shared entanglement, this effect can be compensated by optimally adjusting the initial entangled states. Our results highlight the potential of photon-number encoding for realizing robust entanglement distribution in lossy quantum networks.

DOI: 10.1103/PhysRevA.110.052603

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.110.052603