Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Electronics Letters

77 K RF SQUID with 1/ f noise only below 5 Hz

S.S. Tinchev, Johann Heyen Hinken

Published Nov 9, 1989• 3 citations
Publisher

Abstract

RF SQUIDs were made from bulk YBaCuO ceramic. Using high-density materials one could observe 1/f noise at frequencies as low as only 5 Hz.
DOI
10.1049/el:19891060

Related papers

RF SQUID of 10−28 J/Hz sensitivity at nitrogen temperature

V. I. Shnyrkov, Georgy M. Tsoi, A. G. Kozyr’ +1 more

Superconducting quantum interferometers with a spectral noise density 8·10−29 J/Hz and 2·10−28 J/Hz in the frequency range f > 30 Hz at 77 K are made of polycrystalline bulk ceramics YBaCuO. The measurements are made on SQUID’s with the quantization circuit inductance L ≥ LF(Φ0/2π)1/kBT. It is found that the 1/f-type noises and their boundary frequency depend on the quality of the initial material.

Soviet Journal of Low Temperature Physics•Jul 1, 1988•3 citations

rf break-junction SQUID’s at 77 K

I K Harvey, R.A. Binks, R. Driver

Break-junction rf superconducting quantum interference devices (SQUID’s) have been developed using bulk YBa2Cu3O7 ceramic samples which have been fabricated in the laboratory. The SQUID’s have been produced in both single, and two-hole topologies and their noise characteristics have been measured at 77 K. The equivalent flux noise of the two-hole SQUID at a frequency of 200 Hz was found to be 6.8×10−4 flux quantum/(Hz)1/2.

Applied Physics Letters•May 9, 1988•13 citations

1/f noise in radio frequency SQUIDs made of niobium thin films

Michael Mueck, John L. Clarke, Christoph Heiden

Applications of Superconducting Quantum Interference Devices (SQUIDs) usually require high sensitivity at relatively low frequencies, often down to 1 Hz or lower. Excess noise, typically with a spectral density scaling inversely as the frequency, can substantially reduce the sensitivity of SQUIDs at low frequencies. We have studied 1/f noise in niobium rf-SQUIDs in some detail. To reduce any noise contribution of the readout electronics, a cryogenic preamplifier was used. When one measures the signal voltage of the SQUID directly, a pronounced 1/f noise was observed in all samples, and was nearly independent of the bias frequency used. The crossover between 1/f and white noise moved towards higher frequencies as the bias frequency was increased, because of a lower white noise contribution. The 1/f noise scaled approximately as the inductance of the SQUID. When operated in a flux locked loop, however, no 1/f noise could be observed above 0.5 Hz. Operating a rf SQUID in a flux locked loop can thus substantially reduce 1/f noise in rf SQUIDs.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Jul 2, 1994•0 citations

Fabrication and performance of high T/sub c/ two hole bulk and single hole thick film RF SQUIDs at 77 K

Neeraj Khare, Anurag Gupta, Sangeeta Chaudhry +3 more

Two-hole YBCO bulk and one-hole YBCO, BSCCO thick-film RF SQUIDs have been fabricated and operated at 77 K. RF SQUID behavior has been studied using commercial RF SQUID electronics with external RF and AF sources. Flux noise density of these SQUIDs depends on the quality of the microbridge. Flux noise present in various reported high-T/sub c/ film RF SQUIDs is compared.

IEEE Transactions on Magnetics•Mar 1, 1991•5 citations

Seven-channel RF SQUID with 1/f noises only at very low frequencies

Hiroshi Ohta, M. Takahata, Yoshio Takahashi +7 more

A seven-channel RF SQUID (superconducting quantum interference device) with anodized short weak links has been fabricated. The devices exhibit a sensitivity of 23.6 fT/ square root Hz and a 1/f noise onset of 0.05 Hz at a white noise level of 1.8*10/sup -4/ phi /sub 0// square root Hz. The intrinsic flux noise is estimated from an observed step pattern to be 4.9*10/sup -5/ phi /sub 0// square root Hz. It is shown that Arnold theory explains very well the behavior of Josephson junctions with a critical current density of around 10/sup 4/ A/cm/sup 2/.>

IEEE Transactions on Magnetics•Mar 1, 1989•11 citations

Advances in SQUID magnetometers

John L. Clarke

The operation and noise limitations of de and RF SQUID's are outlined, and recent advances in their sensitivity are discussed. A model of the dc SQUID predicts an energy noise level per hertz referred to the SQUID of approximately8 k_{B}TL/R \approx 8 k_{B}T(\piLC)^{1/2}, whereL, R,andCare the SQUID inductance and the shunt resistance and capacitance of each Josephson junction. Some examples of dc SQUID's are described to show that their performance is generally in reasonable agreement with the model. The noise energy has improved from about 2 × 10-30J. Hz-1for a device withL = 1nH and a tunnel junction area of 104µm2to about 2 × 10-33J . Hz-1for a device withL = 0.1nH and a microbridge resistance of 40 Ω. Further improvements axe expected in the near future. The model of the RF SQUID predicts a noise energy per hertz referred to the SQUID of[(\pi\alpha^{2}\phi\min{0}\max{2}/2L) + 2 \pi \alpha k_{B}T\min{a}\max{(eff)}]/\omega_{RF}, where α is the intrinsic width of the distribution of flux transitions,T\min{a}\max{(eff)}is an effective amplifier noise temperature, and ωRFis the pump frequency. With one exception, the performance of the seven types of RF SQUID listed is in reasonable agreement with the model. The noise energy ranges from about 1.5 × 10-29J . Hz-1for a 20-MHz toroidal SQUID to 3.5 × 10-31J . Hz-1for 9-GHz reentrant toroidal SQUID; a somewhat better sensitivity has been reported for a 430-MHz device, apparently in conflict with the theory. In both dc and RF SQUID's, 1/fnoise (fis frequency) is likely to extend to higher frequencies as the white-noise level is decreased.

IEEE Transactions on Electron Devices•Oct 1, 1980•88 citations
Applications of Superconducting Quantum Interference Devices (SQUIDs) usually require high sensitivity at relatively low frequencies, often down to 1 Hz or lower. Excess noise, typically with a spectral density scaling inversely as the frequency, can substantially reduce the sensitivity of SQUIDs at low frequencies. We have studied 1/f noise in niobium rf-SQUIDs in some detail. To reduce any noise contribution of the readout electronics, a cryogenic preamplifier was used. When one measures the signal voltage of the SQUID directly, a pronounced 1/f noise was observed in all samples, and was nearly independent of the bias frequency used. The crossover between 1/f and white noise moved towards higher frequencies as the bias frequency was increased, because of a lower white noise contribution. The 1/f noise scaled approximately as the inductance of the SQUID. When operated in a flux locked loop, however, no 1/f noise could be observed above 0.5 Hz. Operating a rf SQUID in a flux locked loop can thus substantially reduce 1/f noise in rf SQUIDs.
A seven-channel RF SQUID (superconducting quantum interference device) with anodized short weak links has been fabricated. The devices exhibit a sensitivity of 23.6 fT/ square root Hz and a 1/f noise onset of 0.05 Hz at a white noise level of 1.8*10/sup -4/ phi /sub 0// square root Hz. The intrinsic flux noise is estimated from an observed step pattern to be 4.9*10/sup -5/ phi /sub 0// square root Hz. It is shown that Arnold theory explains very well the behavior of Josephson junctions with a critical current density of around 10/sup 4/ A/cm/sup 2/.>
The operation and noise limitations of de and RF SQUID's are outlined, and recent advances in their sensitivity are discussed. A model of the dc SQUID predicts an energy noise level per hertz referred to the SQUID of approximately8 k_{B}TL/R \approx 8 k_{B}T(\piLC)^{1/2}, whereL, R,andCare the SQUID inductance and the shunt resistance and capacitance of each Josephson junction. Some examples of dc SQUID's are described to show that their performance is generally in reasonable agreement with the model. The noise energy has improved from about 2 × 10-30J. Hz-1for a device withL = 1nH and a tunnel junction area of 104µm2to about 2 × 10-33J . Hz-1for a device withL = 0.1nH and a microbridge resistance of 40 Ω. Further improvements axe expected in the near future. The model of the RF SQUID predicts a noise energy per hertz referred to the SQUID of[(\pi\alpha^{2}\phi\min{0}\max{2}/2L) + 2 \pi \alpha k_{B}T\min{a}\max{(eff)}]/\omega_{RF}, where α is the intrinsic width of the distribution of flux transitions,T\min{a}\max{(eff)}is an effective amplifier noise temperature, and ωRFis the pump frequency. With one exception, the performance of the seven types of RF SQUID listed is in reasonable agreement with the model. The noise energy ranges from about 1.5 × 10-29J . Hz-1for a 20-MHz toroidal SQUID to 3.5 × 10-31J . Hz-1for 9-GHz reentrant toroidal SQUID; a somewhat better sensitivity has been reported for a 430-MHz device, apparently in conflict with the theory. In both dc and RF SQUID's, 1/fnoise (fis frequency) is likely to extend to higher frequencies as the white-noise level is decreased.