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 $19\,\si{\micro\metre}$ thin crystal into a cryogenic Fabry-Perot resonator with a quality factor of $9\cdot {10}^6$, 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 outcoupling 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 $0.54(1)\,\si{\milli\second}$, which exceeds the $0.19(2)\,\si{\milli\second}$ 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Q谐振器中of掺杂剂的相干和赛尔增强发射

定制基质晶体中掺杂剂和其他类原子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领先平台。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：通过将19，\，si {\ micro \ metre} $薄晶体集成到品质因数为1的低温Fabry-Perot谐振器中，$9\cdot {10}^6$，我们实现了两个层次的赛尔因子 $530（50）$。在我们的特定系统中，掺silicate的原硅酸钇可导致$59（6）$发射速率的三倍提高，输出耦合效率为 $46（8）％$。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）\，\ si {\ milli \ second} $的集合平均光学相干，超过腔中掺杂剂的$ 0.19（2）\，si {\ milli \ second} $的寿命字段最大值。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。