中国物理B ›› 2014, Vol. 23 ›› Issue (11): 118501-118501.doi: 10.1088/1674-1056/23/11/118501
• INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY • 上一篇 下一篇
曾佳a b c d, 张懿b c, 邱阳a c d, 张国峰a c, 王永良a c, 孔祥燕a c, 谢晓明a c
Zeng Jia (曾佳)a b c d, Zhang Yi (张懿)b c, Qiu Yang (邱阳)a c d, Zhang Guo-Feng (张国峰)a c, Wang Yong-Liang (王永良)a c, Kong Xiang-Yan (孔祥燕)a c, Xie Xiao-Ming (谢晓明)a c
摘要: We investigate niobium thin film superconducting quantum interference devices (SQUIDs) with different Steward-McCumber parameters βc operated in both current- and voltage-bias modes. We experimentally prove that there is no difference between the two bias modes with respect to the SQUID intrinsic noise and the noise contribution from the preamplifier. Furthermore, the relationships of the SQUID dynamic parameters, (Rd)current bias ≈ (Rd)voltage bias and (∂V/∂Φ)current bias ≈ [(∂i/∂Φ)Rd]voltage bias, are always satisfied. For a strongly damped SQUID with βc ≈ 0.25, additional positive feedback (APF) and noise cancellation (NC) were employed to enhance ∂V/∂Φ, the former showing a degradation in the linear flux range but otherwise the same with NC. For a weakly damped SQUID with βc ≈ 3, it is directly connected to the preamplifier without APF or NC, and a low SQUID system noise of about 4 μΦ 0/√Hz is measured, which is close to its intrinsic noise.
中图分类号: (Superconducting quantum interference devices (SQUIDs))