Effect of parasitic capacitance and inductance on the dynamics and noise of dc superconducting quantum interference devices

Practical thin‐film dc superconducting quantum interference devices (SQUIDs) are often built with an integrated input coil which leads to the formation of various parasitic elements. We have designed and fabricated several square washer‐shaped dc SQUID test devices with various amounts of parasitic capacitance formed by covering the washer slits with superconducting coverplates of various widths. In the simplest approximation, the parasitic capacitance Cp appears entirely across the Josephson junctions; in a better approximation, Cp divides the total inductance into two parts, an effective SQUID loop inductance L and a small parasitic inductance Lp. For both models, noise‐free and noise‐rounded current‐voltage and voltage‐flux characteristics are calculated for various values of the ratios L/Lp and Cp/C, where C is the Josephson junction capacitance. The SQUID dynamics are significantly affected by Cp and Lp. The energy resolution e at first deteriorates with increasing Cp for Cp/C ≲ 2, but as Cp/C become...

[1]  F. Irie,et al.  Effect of damping resistance on voltage versus flux relation of a dc SQUID with large inductance and critical current , 1985 .

[2]  Influence of the signal coil on DC-SQUID dynamics , 1987 .

[3]  C. Tesche.  A thermal activation model for noise in the dc SQUID , 1981 .

[4]  John Clarke,et al.  Measurements of the dynamic input impedance of a dc SQUID , 1985 .

[5]  M. Giannini,et al.  A double DC-SQUID device for flux locked loop operation , 1991 .

[6]  Antti Ahonen,et al.  DC-SQUID electronics based on adaptive positive feedback: experiments , 1991 .

[7]  L. Bär,et al.  Ultra low noise all niobium DC-SQUIDs , 1991 .

[8]  D. Mccumber.  Effect of ac Impedance on dc Voltage‐Current Characteristics of Superconductor Weak‐Link Junctions , 1968 .

[9]  William H. Press,et al.  Numerical recipes in C. The art of scientific computing , 1987 .

[10]  Eshel Ben-Jacob,et al.  Lifetime of oscillatory steady states , 1982 .

[11]  M. Ketchen.  Integrated thin-film dc SQUID sensors , 1987 .

[12]  D. Drung,et al.  Integrated DC SQUID magnetometer with high dV/dB , 1991 .

[13]  G. Tsoi,et al.  On quantum interference in a superconducting ring closed by a weak link , 1980 .

[14]  D. J. Bergman,et al.  Thermal fluctuations and lifetime of the nonequilibrium steady state in a hysteretic Josephson junction , 1982 .

[15]  W. Johnson,et al.  Well coupled, low noise, dc SQUIDs , 1985 .

[16]  J. Waldram,et al.  Superconducting Quantum Interference Devices and their Applications , 1982 .

[17]  H. Koch,et al.  Modeling the direct current superconducting quantum interference device coupled to the multiturn input coil. II , 1992 .

[18]  C. Tesche.  Analysis of a double-loop dc SQUID , 1982 .

[19]  Dietmar Drung,et al.  Low‐noise high‐speed dc superconducting quantum interference device magnetometer with simplified feedback electronics , 1990 .

[20]  W. Lee,et al.  Noise and hysteresis in flux‐locked TlBaCaCuO SQUIDs , 1989 .

[21]  R. Voss,et al.  Ultra low noise Nb DC SQUIDs , 1981 .

[22]  J. Knuutila,et al.  Effects on DC SQUID characteristics of damping of input coil resonances , 1987 .

[23]  E. Ben-Jacob,et al.  Dynamics of the DC‐SQUID , 1981 .

[24]  P. Carelli,et al.  Low‐noise tunnel junction dc SQUID’s , 1981 .

[25]  Matti Kajola,et al.  Design, optimization, and construction of a dc SQUID with complete flux transformer circuits , 1988 .

[26]  D. Drung,et al.  Design and optimization of DC SQUIDs fabricated using a simplified four-level process , 1991 .

[27]  Dietmar Drung,et al.  Practical low‐noise integrated dc superconducting quantum interference device magnetometer with additional positive feedback , 1991 .

[28]  Mark B. Ketchen,et al.  Planar coupling scheme for ultra low noise DC SQUIDs , 1981 .

[29]  D. Drung,et al.  Plasma nitridation process for the fabrication of all‐refractory Josephson junctions , 1990 .

[30]  Mark B. Ketchen,et al.  Practical DC SQUIDs with extremely low 1/f noise , 1985 .

[31]  R. L. Peterson,et al.  Analysis of threshold curves for superconducting interferometers , 1979 .

[32]  J. Clarke,et al.  Superconducting quantum interference device with very low magnetic flux noise energy , 1982 .

[33]  John Clarke,et al.  dc SQUID: Noise and optimization , 1977 .

[34]  V. Ambegaokar,et al.  Numerical calculation of thermal noise-voltage in a Josephson junction of finite capacitance , 1970 .

[35]  M. Castellano,et al.  Toroidal DC SQUIDs with point-contact junctions , 1981 .

[36]  K. Enpuku,et al.  Modeling the dc superconducting quantum interference device coupled to the multiturn input coil , 1991 .

[37]  Instabilities and chaotic solutions of the current biased dc superconducting quantum interference device , 1984 .

[38]  Low noise DC SQUIDs fabricated in Nb-Al/sub 2/O/sub 3/-Nb trilayer technology , 1991 .

[39]  W. C. Stewart,et al.  CURRENT‐VOLTAGE CHARACTERISTICS OF JOSEPHSON JUNCTIONS , 1968 .

[40]  Mark B. Ketchen,et al.  Ultra‐low‐noise tunnel junction dc SQUID with a tightly coupled planar input coil , 1982 .

[41]  R. Voss.  Noise characteristics of an ideal shunted Josephson junction , 1981 .

[42]  J. Hollenhorst,et al.  High sensitivity microwave SQUID , 1979 .

[43]  H. Seppa,et al.  Effect of parasitic capacitance on DC SQUID performance , 1991 .

[44]  J. Clarke,et al.  Signal and noise theory for a dc SQUID amplifier , 1985 .

[45]  Low-frequency noise and discrete charge trapping in small-area tunnel junction dc SQUID's , 1986 .

[46]  V. Foglietti.  Double dc SQUID for flux‐locked‐loop operation , 1991 .

[47]  Risto J. Ilmoniemi,et al.  SQUID magnetometers for low-frequency applications , 1989 .

[48]  Thermally induced escape: The principle of minimum available noise energy. , 1988, Physical review. A, General physics.

[49]  H. Scheer,et al.  Integrated DC SQUID magnetometer with simplified read-out , 1990 .