The stability and outstanding coherence of dopants and other atom-like defects in tailored host crystals make them a leading platform for the implementation of distributed quantum information processing and sensing in quantum networks. Albeit the required efficient light-matter coupling can be achieved via the integration into nanoscale resonators, in this approach the proximity of interfaces is detrimental to the coherence of even the least-sensitive emitters. Here, we establish an alternative: By integrating a 19 micrometer thin erbium-doped crystal into a cryogenic Fabry-Perot resonator with a quality factor of nine million, we can demonstrate 59(6)-fold enhancement of the emission rate, corresponding to a two-level Purcell factor of 530(50), while preserving lifetime-limited optical coherence up to 0.54(1) ms. With its emission at the minimal-loss wavelength of optical fibers and its outcoupling efficiency of 46(8) %, our system enables coherent and efficient nodes for long-distance quantum networks.
Room temperature Purcell enhanced single erbium ions in silicon-carbide-on-insulator microring resonators
RMIT University（皇家墨尔本理工大学）；National Institutes for Quantum Science and Technology（国立量子科学技术研究院）；The University of Melbourne（墨尔本大学）；Carnegie Mellon University（卡内基梅隆大学）
Elucidating magnetic structure with optical dopants: erbium-doped Gd$_2$SiO$_5$
University of Otago（奥塔哥大学）；Dodd-Walls Centre for Photonic and Quantum Technologies（光子与量子技术多兹中心）；Quantum Innovation Centre (Q.InC), Agency for Science, Technology and Research (A*STAR)（科学技术研究局（A*STAR）量子创新中心）；Centre for Quantum Technologies, National University of Singapore（新加坡国立大学量子技术中心）
A Si-on-SiC Platform for Interfacing with Vanadium Dopants in the Telecom O-Band
Q-NEXT, Argonne National Laboratory（Q-NEXT，阿贡国家实验室）；Pritzker School of Molecular Engineering, University of Chicago（芝加哥大学普里茨克分子工程学院）；Material Science Division, Argonne National Laboratory（阿贡国家实验室材料科学部）；Center for Nanoscale Materials, Argonne National Laboratory（阿贡国家实验室纳米材料中心）
Coupling between CaWO$_4$ phonons and Er$^{3+}$ dopants
Agency for Science, Technology and Research (A*STAR)（科学与技术研究局）；Centre for Quantum Technologies, National University of Singapore（新加坡国立大学量子技术中心）；Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL)（洛桑联邦理工学院物理研究所）；National University of Singapore（新加坡国立大学）；Australian Center for Neutron Scattering, Australian Nuclear Science and Technology Organization（澳大利亚核科学与技术组织中子散射中心）；Paul Scherrer Institut Center for Neutron and Muon Sciences（保罗谢尔研究所中子与μ子科学中心）
Spectral stability of cavity-enhanced single-photon emitters in silicon
Technical University of Munich（慕尼黑工业大学）；Munich Center for Quantum Science and Technology (MCQST)（慕尼黑量子科学与工程中心）；TUM Center for Quantum Engineering (ZQE)（慕尼黑工业大学量子工程中心）；Max-Planck-Institut für Quantenoptik（马克斯·普朗克量子光学研究所）
