The stability and outstanding coherence of dopants and other atomlike 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 $19\mu \mathrm{m}$ thin crystal into a cryogenic Fabry-Perot resonator with a quality factor of $9\times {10}^6$, we achieve a two-level Purcell factor of 530(50). In our specific system, erbium-doped yttrium orthosilicate, this leads to a 59(6)-fold enhancement of the emission rate with an out-coupling efficiency of 46(8)%. At the same time, we demonstrate that the emitter properties are not degraded in our approach. We thus observe ensemble-averaged optical coherence up to 0.54(1) ms, which exceeds the 0.19(2) ms lifetime of dopants at the cavity field maximum. While our approach is also applicable to other solid-state quantum emitters, such as color centers in diamond, our system emits at the minimal-loss wavelength of optical fibers and thus enables coherent and efficient nodes for long-distance quantum networks.

中文翻译：

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低温高QResonator中from掺杂物的相干和赛尔增强发射

定制基质晶体中掺杂剂和其他原子状缺陷的稳定性和出色的相干性使其成为在量子网络中实施分布式量子信息处理和传感的主要平台。尽管可以通过集成到纳米级谐振器中来实现所需的有效光-质耦合，但是在这种方法中，界面的接近度甚至对最不敏感的发射器的相干性都是有害的。在这里，我们建立了一个替代方案：$19\mu \mathrm{米}$ 将薄晶体制成品质因数为1的低温Fabry-Perot谐振器 $9\times {10}^6$，我们达到了530（50）的二级塞塞尔系数。在我们的特定系统（掺er的原硅酸钇）中，发射速率提高了59（6）倍，耦合效率为46（8）％。同时，我们证明了我们的方法不会降低发射极的性能。因此，我们观察到高达0.54（1）ms的集合平均光学相干性，该相干性超过了腔场最大值处掺杂剂的0.19（2）ms寿命。尽管我们的方法也适用于其他固态量子发射器，例如钻石中的色心，但我们的系统以光纤的最小损耗波长发射，因此可以为长距离量子网络提供相干且高效的节点。