标题： 腔增强的密集浴中单个核自旋的光谱学 显示英文标题

标题： Cavity-enhanced spectroscopy of individual nuclear spins in a dense bath

摘要： 基于回声的光谱学方法，用于研究电子自旋与周围核自旋之间的超超精细相互作用，能够深入了解固体中自旋的微观磁环境。 然而，在密集的核自旋浴中分辨单个核自旋仍是一个悬而未决的挑战，其中许多核自旋表现出相近的耦合强度。 这同时需要高光谱分辨率和大的信噪比。 然而，当探测自旋集合时，掺杂剂之间的偶极相互作用会导致分辨率和信号之间的浓度依赖性权衡。 在此，我们通过将发射器集成到高精细度谐振腔中，完全消除了之前光学回声包络调制光谱实验的这一限制，该谐振腔即使在非常低的浓度下也能产生强光学回声。 为了展示其潜力，该技术被应用于钇正硅酸盐中的铒掺杂剂（Er:YSO）。 实现前所未有的光谱分辨率，使得能够精确测量每个发射器周围四个密集的Y核自旋的超超精细相互作用。 由谐振腔带来的信号增强，使得该方法可以扩展到可能的最低浓度——达到单个掺杂剂的水平，从而提供了一种检测和研究单个核自旋的工具。 因此，我们的技术为更深入地理解固体中密集的核自旋浴铺平了道路。 显示英文摘要

摘要： Echo-based spectroscopy of the superhyperfine interaction of an electronic spin with nuclear spins in its surroundings enables detailed insights into the microscopic magnetic environment of spins in solids. Still, it is an outstanding challenge to resolve individual nuclear spins in a dense bath, in which many of them exhibit a comparable coupling strength. This simultaneously requires a high spectral resolution and a large signal-to-noise ratio. However, when probing spin ensembles, dipolar interactions between the dopants can lead to a concentration-dependent trade-off between resolution and signal. Here, we fully eliminate this limitation of previous optical-echo-envelope-modulation spectroscopy experiments by integrating the emitters into a high-finesse resonator, which allows for strong optical echoes even at very low concentrations. To demonstrate its potential, the technique is applied to erbium dopants in yttrium-orthosilicate (Er:YSO). Achieving an unprecedented spectral resolution enables precise measurements of the superhyperfine interaction with four of the Y nuclear spins densely surrounding each emitter. The achieved boost of the signal, enabled by the resonator, allows for extending the approach to the lowest concentration possible -- to the level of single dopants, thereby providing a tool for detecting and studying individual nuclear spins. Thus, our technique paves the way for an improved understanding of dense nuclear spin baths in solids.