近日，英国剑桥大学Mete Atature及其研究小组与美国麻省理工学院的Dirk Englund等人合作并取得一项新进展。经过不懈努力，他们对具有光学可及的确定性电子核自旋寄存器的金刚石纳米光子界面进行研究。相关研究成果已于2023年11月13日在国际知名学术期刊《自然—光子学》上发表。
该研究团队开发了一种光纤封装的纳米光子金刚石波导，其特点是拥有一个自旋为1/2的117Sn核的锡空穴中心。电子与核自旋间的交互作用产生了452(7)MHz的特征超精细分裂，该数值超过了自然光学线宽的16倍。这使得直接光学核自旋初始化保真度高达98.6(3)%，单次读出保真度为80.0(1)%。
此外，该器件的波导到光纤的提取效率为57(6)%，能实际检测五光子事件。结合其光子性能与光学初始化的核自旋，研究人员在没有外部磁场的情况下，成功实现了自旋门控的单光子非线性比为11(1)%。这些功能使他们的纳米光子接口成为追求可扩展量子网络的通用量子节点的理想选择。
据悉，当前对量子网络可扩展性的挑战，是开发同时具有高光子效率和长寿命量子比特的量子节点。
附：英文原文
Title: A diamond nanophotonic interface with an optically accessible deterministic electronuclear spin register
Author: Parker, Ryan A., Arjona Martnez, Jess, Chen, Kevin C., Stramma, Alexander M., Harris, Isaac B., Michaels, Cathryn P., Trusheim, Matthew E., Hayhurst Appel, Martin, Purser, Carola M., Roth, William G., Englund, Dirk, Atature, Mete
Issue&Volume: 2023-11-13
Abstract: A contemporary challenge for the scalability of quantum networks is developing quantum nodes with simultaneous high photonic efficiency and long-lived qubits. Here we present a fibre-packaged nanophotonic diamond waveguide hosting a tin-vacancy centre with a spin-1/2 117Sn nucleus. The interaction between the electronic and nuclear spins results in a signature 452(7)MHz hyperfine splitting. This exceeds the natural optical linewidth by a factor of 16, enabling direct optical nuclear spin initialization with 98.6(3)% fidelity and single-shot readout with 80.0(1)% fidelity. The waveguide-to-fibre extraction efficiency of our device of 57(6)% enables the practical detection of five-photon events. Combining the photonic performance with the optically initialized nuclear spin, we demonstrate a spin-gated single-photon nonlinearity with 11(1)% contrast in the absence of an external magnetic field. These capabilities position our nanophotonic interface as a versatile quantum node in the pursuit of scalable quantum networks.
DOI: 10.1038/s41566-023-01332-8
Source: https://www.nature.com/articles/s41566-023-01332-8