We introduce a miniaturized magnetic shield integrated into the physics package of a chip-scale atomic clock. The primary shield, which is formed by a stack of precision-machined high-permeability plates, compactly sits inside the package as it is designed to be the internal supporting frame. Further improved by a Kovar lid, the best frequency sensitivity to a longitudinal external field is 1.1(3) × 10−11/μT, which is consistent with the measured shielding factor, while the transverse sensitivity is well below 10−12/μT. The sealed unit on a chip carrier alone allows stable clock operation with a frequency instability of 4.8(2) × 10−12 at 1000 s.

中文翻译：

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用于芯片级原子钟的磁屏蔽集成

我们将微型磁屏蔽集成到芯片级原子钟的物理封装中。主屏蔽由一堆精密加工的高渗透板组成，紧凑地位于包装内，因为它被设计为内部支撑框架。Kovar 盖进一步改进后，对纵向外场的最佳频率灵敏度为 1.1(3) × 10-11/μT，与测量的屏蔽系数一致，而横向灵敏度远低于 10-12/μT。单独在芯片载体上的密封单元允许稳定的时钟操作，在 1000 秒时频率不稳定性为 4.8(2) × 10−12。