Noise measurements on multiloop dc SQUIDs, fabricated with Nb‐NbOx‐PbAuIn and Pb‐alloy Josephson tunnel junctions and well coupled with the external world by an input coil, we performed in flux locked loop mode. To achieve this task, we built a reliable low‐cost control electronics to detect the voltage output of the SQUID. The results show that for multiloop dc SQUIDs with single‐junction critical currents larger than 20 mgr;A and an inductive parameter bgr;Lless than 4.5, an intrinsic white‐energy spectral density of about 100hcan be obtained independently of the technology used to fabricate the junctions. Furthermore, the Nb‐NbOx‐PbAuIn dc SQUIDs have a lower 1/f noise than the Pb‐alloy ones.
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机译：在多回路直流SQUID上进行噪声测量，使用Nb‐NbOx&hyphen‐PbAuIn和Pb‐alloy Josephson隧道结制造，并通过输入线圈与外部世界很好地耦合，我们在磁通锁环模式下进行。为了完成这项任务，我们构建了一个可靠的低成本控制电子设备来检测SQUID的电压输出。结果表明，对于单结临界电流大于20 &mgr;A且电感参数&bgr;L小于4.5的多环直流SQUIDs，可以独立于结的制备技术获得约100h的固有白谱能谱密度。此外，Nb‐NbOx‐PbAuIn dc SQUID的噪声低于Pb‐alloys。
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