A coupled DC SQUID with low 1/f noise

Heikki Seppä; Mikko Kiviranta; Alexandre Satrapinski; Leif Grönberg; Jorma Salmi; Ilkka Suni

doi:10.1109/77.233329

A coupled DC SQUID with low 1/f noise

Heikki Seppä, Mikko Kiviranta, Alexandre Satrapinski, Leif Grönberg, Jorma Salmi, Ilkka Suni

Research output: Contribution to journal › Article › Scientific › peer-review

26 Citations (Scopus)

Abstract

A low-noise coupled DC superconducting quantum interference device (SQUID) especially optimized for low frequency is discussed. Using large Josephson junctions and a low loop inductance the contribution of the critical current fluctuation to 1/f noise can be minimized. To minimize the inductance the Josephson junctions are placed in the center of the washer close to the SQUID loop. A scaled-up copper model of the SQUID and the signal coil is used to analyze the impedance of the SQUID loop affected by the signal coil. An equivalent circuit model describing the effective inductance of the SQUID loop as a function of the frequency is used to design appropriate damping of the resonances. The DC SQUID characteristics are smooth and the noise performance of the SQUID does not markedly suffer from resonances. The contribution of the 1/f noise at 1 Hz is found to be about 5*10^-7 φ₀ √Hz.

Original language	English
Pages (from-to)	1816 - 1819
Number of pages	4
Journal	IEEE Transactions on Applied Superconductivity
Volume	3
Issue number	1
DOIs	https://doi.org/10.1109/77.233329
Publication status	Published - 1993
MoE publication type	A1 Journal article-refereed

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title = "A coupled DC SQUID with low 1/f noise",

abstract = "A low-noise coupled DC superconducting quantum interference device (SQUID) especially optimized for low frequency is discussed. Using large Josephson junctions and a low loop inductance the contribution of the critical current fluctuation to 1/f noise can be minimized. To minimize the inductance the Josephson junctions are placed in the center of the washer close to the SQUID loop. A scaled-up copper model of the SQUID and the signal coil is used to analyze the impedance of the SQUID loop affected by the signal coil. An equivalent circuit model describing the effective inductance of the SQUID loop as a function of the frequency is used to design appropriate damping of the resonances. The DC SQUID characteristics are smooth and the noise performance of the SQUID does not markedly suffer from resonances. The contribution of the 1/f noise at 1 Hz is found to be about 5*10-7 φ0 √Hz.",

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T1 - A coupled DC SQUID with low 1/f noise

AU - Seppä, Heikki

AU - Kiviranta, Mikko

AU - Satrapinski, Alexandre

AU - Grönberg, Leif

AU - Salmi, Jorma

AU - Suni, Ilkka

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AB - A low-noise coupled DC superconducting quantum interference device (SQUID) especially optimized for low frequency is discussed. Using large Josephson junctions and a low loop inductance the contribution of the critical current fluctuation to 1/f noise can be minimized. To minimize the inductance the Josephson junctions are placed in the center of the washer close to the SQUID loop. A scaled-up copper model of the SQUID and the signal coil is used to analyze the impedance of the SQUID loop affected by the signal coil. An equivalent circuit model describing the effective inductance of the SQUID loop as a function of the frequency is used to design appropriate damping of the resonances. The DC SQUID characteristics are smooth and the noise performance of the SQUID does not markedly suffer from resonances. The contribution of the 1/f noise at 1 Hz is found to be about 5*10-7 φ0 √Hz.

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