中国物理B ›› 2005, Vol. 14 ›› Issue (3): 592-598.doi: 10.1088/1009-1963/14/3/030

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Analytical theory of DC SQUID with a resistively shunted inductance driven by thermal noises

辜姣1, 黄新堂1, 吕海峰2   

  1. (1)Department of Physics, Central China Normal University, Wuhan 430079, China; (2)Department of Physics, Central China Normal University, Wuhan 430079, China; Department of Physics, Tsinghua University, Beijing 100084, China
  • 收稿日期:2004-05-14 修回日期:2004-10-14 出版日期:2005-03-02 发布日期:2005-03-02

Analytical theory of DC SQUID with a resistively shunted inductance driven by thermal noises

Lü Hai-Feng (吕海峰)ab, Gu Jiao (辜姣)a, Huang Xin-Tang (黄新堂)a   

  1. a Department of Physics, Central China Normal University, Wuhan 430079, China; b Department of Physics, Tsinghua University, Beijing 100084, China
  • Received:2004-05-14 Revised:2004-10-14 Online:2005-03-02 Published:2005-03-02

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摘要： An analytical expression for the stationary probability distribution of the DC superconducting quantum interference device (SQUID) with a resistively shunted inductance driven by thermal noise is derived from the two-dimensional Fokker—Planck equation. The effects on the SQUID characteristics subject to a large thermal fluctuation with a noise parameter $\varGamma$ >0.20 are discussed by taking into account the thermal noise in the accuracy of numerical simulation. This theory is valid for a reduced inductance β≤1. The analytical formulae for the SQUID characteristics, e.g. the circulating current, the average voltage and the voltage modulation, are obtained and discussed. The theory shows that the voltage modulation increases with the shunted inductance more efficiently for a large inductance parameter β and small fluctuation parameter Γ.

关键词: noise, Fokker—Planck equation, SQUID, shunted

Abstract: An analytical expression for the stationary probability distribution of the DC superconducting quantum interference device (SQUID) with a resistively shunted inductance driven by thermal noise is derived from the two-dimensional Fokker—Planck equation. The effects on the SQUID characteristics subject to a large thermal fluctuation with a noise parameter $\varGamma$ >0.20 are discussed by taking into account the thermal noise in the accuracy of numerical simulation. This theory is valid for a reduced inductance $\beta$ ≤1. The analytical formulae for the SQUID characteristics, e.g. the circulating current, the average voltage and the voltage modulation, are obtained and discussed. The theory shows that the voltage modulation increases with the shunted inductance more efficiently for a large inductance parameter β and small fluctuation parameter $\varGamma$.

Key words: noise, Fokker—Planck equation, SQUID, shunted

中图分类号:  (Superconducting quantum interference devices (SQUIDs))

  • 85.25.Dq
85.25.Am (Superconducting device characterization, design, and modeling)