Design and optimization of DC SQUIDs fabricated using a simplified four-level process

Robin Cantor; Tapani Ryhänen; Dietmar Drung; Hans Koch; Heikki Seppä

doi:10.1109/20.133822

Design and optimization of DC SQUIDs fabricated using a simplified four-level process

Robin Cantor, Tapani Ryhänen, Dietmar Drung, Hans Koch, Heikki Seppä

German National Metrology Institute (PTB)

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

25 Citations (Scopus)

Abstract

An optimization procedure is presented which is used to design two types of ultralow-noise DC superconducting quantum interference devices (SQUIDs) with integrated flux coupling circuits, a magnetometer, and a gradiometer. Essential to this design approach is the reduction of the parasitic capacitance, the choice of a layout which moves the input coil resonances well away from the desired operating frequency of the SQUID, and the proper damping of these resonances. It is shown that both the microwave and LC resonances can be damped in a nearly noise-free manner by placing all RC shunt in parallel with the input coil. This leads to smooth voltage-flux modulation characteristics and significantly improved noise performance. A simple, four-level Nb/Si_x/N_y/Nb Josephson junction technology for device fabrication is described. White flux noise levels of 5*10^-7φ₀/√Hz for the magnetometer and 7.9*10^-7φ₀/√Hz for the gradiometer were measured. The corresponding uncoupled energy resolutions are 100 h and 130 h, respectively. The 1/f noise of the magnetometer at 1 Hz is less than 4*10^-6φ₀/√Hz.

Original language	English
Pages (from-to)	2927 - 2931
Number of pages	5
Journal	IEEE Transactions on Magnetics
Volume	27
Issue number	2
DOIs	https://doi.org/10.1109/20.133822
Publication status	Published - 1991
MoE publication type	A1 Journal article-refereed

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10.1109/20.133822

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@article{834f970a44b54c0189ef4f725f4a70f6,

title = "Design and optimization of DC SQUIDs fabricated using a simplified four-level process",

abstract = "An optimization procedure is presented which is used to design two types of ultralow-noise DC superconducting quantum interference devices (SQUIDs) with integrated flux coupling circuits, a magnetometer, and a gradiometer. Essential to this design approach is the reduction of the parasitic capacitance, the choice of a layout which moves the input coil resonances well away from the desired operating frequency of the SQUID, and the proper damping of these resonances. It is shown that both the microwave and LC resonances can be damped in a nearly noise-free manner by placing all RC shunt in parallel with the input coil. This leads to smooth voltage-flux modulation characteristics and significantly improved noise performance. A simple, four-level Nb/Six/Ny/Nb Josephson junction technology for device fabrication is described. White flux noise levels of 5*10-7φ0/√Hz for the magnetometer and 7.9*10-7φ0/√Hz for the gradiometer were measured. The corresponding uncoupled energy resolutions are 100 h and 130 h, respectively. The 1/f noise of the magnetometer at 1 Hz is less than 4*10-6φ0/√Hz.",

author = "Robin Cantor and Tapani Ryh{\"a}nen and Dietmar Drung and Hans Koch and Heikki Sepp{\"a}",

note = "Project code: S{\"A}H1201",

year = "1991",

doi = "10.1109/20.133822",

language = "English",

volume = "27",

pages = "2927 -- 2931",

journal = "IEEE Transactions on Magnetics",

issn = "0018-9464",

publisher = "IEEE Institute of Electrical and Electronic Engineers",

number = "2",

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TY - JOUR

T1 - Design and optimization of DC SQUIDs fabricated using a simplified four-level process

AU - Cantor, Robin

AU - Ryhänen, Tapani

AU - Drung, Dietmar

AU - Koch, Hans

AU - Seppä, Heikki

N1 - Project code: SÄH1201

PY - 1991

Y1 - 1991

N2 - An optimization procedure is presented which is used to design two types of ultralow-noise DC superconducting quantum interference devices (SQUIDs) with integrated flux coupling circuits, a magnetometer, and a gradiometer. Essential to this design approach is the reduction of the parasitic capacitance, the choice of a layout which moves the input coil resonances well away from the desired operating frequency of the SQUID, and the proper damping of these resonances. It is shown that both the microwave and LC resonances can be damped in a nearly noise-free manner by placing all RC shunt in parallel with the input coil. This leads to smooth voltage-flux modulation characteristics and significantly improved noise performance. A simple, four-level Nb/Six/Ny/Nb Josephson junction technology for device fabrication is described. White flux noise levels of 5*10-7φ0/√Hz for the magnetometer and 7.9*10-7φ0/√Hz for the gradiometer were measured. The corresponding uncoupled energy resolutions are 100 h and 130 h, respectively. The 1/f noise of the magnetometer at 1 Hz is less than 4*10-6φ0/√Hz.

AB - An optimization procedure is presented which is used to design two types of ultralow-noise DC superconducting quantum interference devices (SQUIDs) with integrated flux coupling circuits, a magnetometer, and a gradiometer. Essential to this design approach is the reduction of the parasitic capacitance, the choice of a layout which moves the input coil resonances well away from the desired operating frequency of the SQUID, and the proper damping of these resonances. It is shown that both the microwave and LC resonances can be damped in a nearly noise-free manner by placing all RC shunt in parallel with the input coil. This leads to smooth voltage-flux modulation characteristics and significantly improved noise performance. A simple, four-level Nb/Six/Ny/Nb Josephson junction technology for device fabrication is described. White flux noise levels of 5*10-7φ0/√Hz for the magnetometer and 7.9*10-7φ0/√Hz for the gradiometer were measured. The corresponding uncoupled energy resolutions are 100 h and 130 h, respectively. The 1/f noise of the magnetometer at 1 Hz is less than 4*10-6φ0/√Hz.

U2 - 10.1109/20.133822

DO - 10.1109/20.133822

M3 - Article

SN - 0018-9464

VL - 27

SP - 2927

EP - 2931

JO - IEEE Transactions on Magnetics

JF - IEEE Transactions on Magnetics

IS - 2

ER -

Design and optimization of DC SQUIDs fabricated using a simplified four-level process

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