Low noise operation of a DC squid in a large β regime and its application to the design of a high TC squid

K. Enpuku; S. Kohjiro; K. Yoshida

doi:10.1109/20.92494

Low noise operation of a DC squid in a large β regime and its application to the design of a high TC squid

K. Enpuku, S. Kohjiro, K. Yoshida

Superconductive Systems Engineering Laboratory

Research output: Contribution to journal › Article

2 Citations (Scopus)

Abstract

Noise characteristics of a large-β dc SQUID have been studied experimentally in the case when a SQUID inductance is resistively shunted. Here, ß=2LIo/¢o is a modulation parameter, L is a SQUID inductance, Io is a critical current and ¢o is the flux quantum. Energy resolutions of the SQUIDs, ε, have been measured for various β values up to β=19. It is shown experimentally that energy resolutions of the present large-β SQUIDs are as small as that of the conventional SQUID with β=1. For example, energy resolution ε=25h was obtained even for β=12(L=340pH and Io=37µA), where his the Planck constant. The obtained experimental results agree quantitatively with theoretical ones. It is also shown that the present resistively-shunted-inductance scheme is very useful in developing SQUIDs operating at T=77k with high-Tc superconductors, where the value of β will become necessarily large in order to avoid noise effects. Numerical simulations on the performance of the high-Tc SQUID are presented.

Original language	English
Pages (from-to)	1154-1157
Number of pages	4
Journal	IEEE Transactions on Magnetics
Volume	25
Issue number	2
DOIs	https://doi.org/10.1109/20.92494
Publication status	Published - Mar 1989

All Science Journal Classification (ASJC) codes

Electronic, Optical and Magnetic Materials
Electrical and Electronic Engineering

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Enpuku, K., Kohjiro, S., & Yoshida, K. (1989). Low noise operation of a DC squid in a large β regime and its application to the design of a high TC squid. IEEE Transactions on Magnetics, 25(2), 1154-1157. https://doi.org/10.1109/20.92494

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title = "Low noise operation of a DC squid in a large β regime and its application to the design of a high TC squid",

abstract = "Noise characteristics of a large-β dc SQUID have been studied experimentally in the case when a SQUID inductance is resistively shunted. Here, {\ss}=2LIo/¢o is a modulation parameter, L is a SQUID inductance, Io is a critical current and ¢o is the flux quantum. Energy resolutions of the SQUIDs, ε, have been measured for various β values up to β=19. It is shown experimentally that energy resolutions of the present large-β SQUIDs are as small as that of the conventional SQUID with β=1. For example, energy resolution ε=25h was obtained even for β=12(L=340pH and Io=37µA), where his the Planck constant. The obtained experimental results agree quantitatively with theoretical ones. It is also shown that the present resistively-shunted-inductance scheme is very useful in developing SQUIDs operating at T=77k with high-Tc superconductors, where the value of β will become necessarily large in order to avoid noise effects. Numerical simulations on the performance of the high-Tc SQUID are presented.",

author = "K. Enpuku and S. Kohjiro and K. Yoshida",

year = "1989",

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doi = "10.1109/20.92494",

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AU - Enpuku, K.

AU - Kohjiro, S.

AU - Yoshida, K.

PY - 1989/3

Y1 - 1989/3

N2 - Noise characteristics of a large-β dc SQUID have been studied experimentally in the case when a SQUID inductance is resistively shunted. Here, ß=2LIo/¢o is a modulation parameter, L is a SQUID inductance, Io is a critical current and ¢o is the flux quantum. Energy resolutions of the SQUIDs, ε, have been measured for various β values up to β=19. It is shown experimentally that energy resolutions of the present large-β SQUIDs are as small as that of the conventional SQUID with β=1. For example, energy resolution ε=25h was obtained even for β=12(L=340pH and Io=37µA), where his the Planck constant. The obtained experimental results agree quantitatively with theoretical ones. It is also shown that the present resistively-shunted-inductance scheme is very useful in developing SQUIDs operating at T=77k with high-Tc superconductors, where the value of β will become necessarily large in order to avoid noise effects. Numerical simulations on the performance of the high-Tc SQUID are presented.

AB - Noise characteristics of a large-β dc SQUID have been studied experimentally in the case when a SQUID inductance is resistively shunted. Here, ß=2LIo/¢o is a modulation parameter, L is a SQUID inductance, Io is a critical current and ¢o is the flux quantum. Energy resolutions of the SQUIDs, ε, have been measured for various β values up to β=19. It is shown experimentally that energy resolutions of the present large-β SQUIDs are as small as that of the conventional SQUID with β=1. For example, energy resolution ε=25h was obtained even for β=12(L=340pH and Io=37µA), where his the Planck constant. The obtained experimental results agree quantitatively with theoretical ones. It is also shown that the present resistively-shunted-inductance scheme is very useful in developing SQUIDs operating at T=77k with high-Tc superconductors, where the value of β will become necessarily large in order to avoid noise effects. Numerical simulations on the performance of the high-Tc SQUID are presented.

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