近日，美国哈佛大学的M. D.Lukin及其研究团队取得一项新进展。经过不懈努力，他们实现电信网络中纳米光子量子存储节点的纠缠。相关研究成果已于2024年5月15日在国际权威学术期刊《自然》上发表。

该研究团队展示了一个由基于纳米光子金刚石腔中的硅空穴(SiV)中心的多量子比特寄存器组成的双节点量子网络，该寄存器与电信光纤网络集成。远程纠缠的产生依赖于SiV中心电子自旋量子比特与光子之间的腔增强相互作用。通过序列化和预示自旋光子纠缠门操作，以及时间段量子比特的应用，该网络在分离节点间实现了鲁棒的纠缠。此外，长寿命的核自旋量子比特被用作存储单元，提供了秒级的纠缠存储能力，并集成了错误检测机制。

通过将光子通信量子比特的有效双向量子频率转换集成到电信频率（1350nm），研究人员在波士顿地区城市环境中部署的40公里低损耗光纤线轴和35公里长的光纤环路中，成功展示了两个核自旋存储器的纠缠，代表了向实用量子中继器和大规模量子网络迈出的坚实一步。

据悉，实现远距离量子通信的实用量子网络所面临的关键挑战在于，确保光纤基础设施连接的量子存储节点之间能够建立鲁棒且稳定的纠缠。

附：英文原文

Title: Entanglement of nanophotonic quantum memory nodes in a telecom network

Author: Knaut, C. M., Suleymanzade, A., Wei, Y.-C., Assumpcao, D. R., Stas, P.-J., Huan, Y. Q., Machielse, B., Knall, E. N., Sutula, M., Baranes, G., Sinclair, N., De-Eknamkul, C., Levonian, D. S., Bhaskar, M. K., Park, H., Lonar, M., Lukin, M. D.

Issue&Volume: 2024-05-15

Abstract: A key challenge in realizing practical quantum networks for long-distance quantum communication involves robust entanglement between quantum memory nodes connected by fibre optical infrastructure. Here we demonstrate a two-node quantum network composed of multi-qubit registers based on silicon-vacancy (SiV) centres in nanophotonic diamond cavities integrated with a telecommunication fibre network. Remote entanglement is generated by the cavity-enhanced interactions between the electron spin qubits of the SiVs and optical photons. Serial, heralded spin-photon entangling gate operations with time-bin qubits are used for robust entanglement of separated nodes. Long-lived nuclear spin qubits are used to provide second-long entanglement storage and integrated error detection. By integrating efficient bidirectional quantum frequency conversion of photonic communication qubits to telecommunication frequencies (1,350nm), we demonstrate the entanglement of two nuclear spin memories through 40km spools of low-loss fibre and a 35-km long fibre loop deployed in the Boston area urban environment, representing an enabling step towards practical quantum repeaters and large-scale quantum networks.

DOI: 10.1038/s41586-024-07252-z

Source: https://www.nature.com/articles/s41586-024-07252-z