We report on the development of magnetic background field-tolerant superconducting quantum interference filter (SQIF) based on low-capacitance sub-micrometer sized cross-type Josephson junctions either as current sensing amplifiers—even on chip—for advanced superconducting quantum interference device (SQUID) readout circuits or as magnetic field sensor in flux transformer configuration especially for geophysical measurement systems. Their very small parasitic magnetic sensitive areas enable them to operate in the Earth magnetic field and allow for magnetically unshielded cool-down. The careful consideration of magnetic sensitive areas inside each SQUID in the SQIF in all three dimensions result in developed SQIFs with 28 SQUIDs in series exhibiting large voltage swing and transfer function of more than 2 mV and , respectively. We report on the electrical parameters and field stability as well as on the noise performance of the devices under investigation. SQIFs and devices with additional on-chip flux-transformers show input referred current noise levels of and , respectively. We furthermore demonstrate their potential as SQIF-based magnetometers using them in addition with thin-film pickup loops resulting in a white magnetic field noise of . The implemented SQIFs are thus highly compatible with state-of-the-art single SQUID-devices offering beneficial features such as a unique working point, making them excellent suited for implementation of e.g. geophysical instruments.

我们报告了基于低电容亚微米尺寸的交叉型约瑟夫逊结的磁性本底磁场超导量子干扰滤波器（SQIF）的开发情况，该滤波器既可作为电流检测放大器（甚至在芯片上使用），也可用于高级超导量子干扰器件（SQUID） ）读出电路，或用作磁通互感器配置中的磁场传感器，特别是用于地球物理测量系统。它们很小的寄生磁敏感区域使它们可以在地磁场中工作，并可以进行无磁屏蔽的冷却。仔细考虑SQIF中每个SQUID内部在所有三个维度上的磁敏感区域，会导致开发的SQIF具有28个串联的SQUID，表现出较大的电压摆幅和超过2 mV的传递函数，并且， 分别。我们报告了电气参数和场稳定性以及所研究设备的噪声性能。SQIF和带有附加片上通量互感器的设备分别显示输入参考电流噪声水平和。此外，我们还证明了它们作为基于SQIF的磁力计的潜力，除了薄膜拾取回路外还使用了SQIF磁力计，产生的白磁场噪声为。因此，已实现的SQIF与最新的单个SQUID设备高度兼容，可提供诸如独特的工作点之类的有益功能，使其非常适合于例如地球物理仪器的实现。