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

Book · Sat Dec 31 04:00:00 EST 1994

OSTI ID:64695

Mueck, M ^[1]; Clarke, J ^[2]; Heiden, C ^[3]

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1. Forschungszentrum Juelich (Germany). Inst. fuer Schicht- und Ionentechnik
2. Univ. of California, Berkeley, CA (United States). Dept. of Physics
3. Univ. Giessen (Germany). Inst. fuer Angewandte Physik

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. The authors 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.

• OSTI ID: 64695
• Report Number(s): CONF-940142--; ISBN 0-8194-1455-7
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
EXPERIMENTAL DATA
FREQUENCY DEPENDENCE
HIGH-TC SUPERCONDUCTORS
MAGNETIC FLUX
NOISE
OPERATION
READOUT SYSTEMS
SQUID DEVICES