Very low noise, tightly coupled, dc SQUID amplifiers

Journal Article · Sun Oct 26 23:00:00 EST 1986 · Appl. Phys. Lett.; (United States)

DOI:https://doi.org/10.1063/1.97440· OSTI ID:5262597

Muhlfelder, B; Beall, J A; Cromar, M W; Ono, R H

We have fabricated and tested thin film, niobium edge junction, double transformer, dc superconducting quantum interference devices (SQUID's) that were stable under room-temperature storage and thermal cycling and that had very good noise performance. The input inductance, approximately 1.7 ..mu..H, was large enough to facilitate good matching to many experiments. When the SQUID was operated as a small-signal amplifier, the minimum detectable energy per unit bandwidth (S/sub e/) was 5 x 10/sup -33/ J/Hz at 100 kHz, referred to the SQUID loop (uncoupled). The minimum detectable energy per unit bandwidth was 1.8 x 10/sup -31/ J/Hz at 100 kHz, referred to the input coil. The SQUID's had good characteristics for flux-locked operation since the small signal S/sub e/ was low over a substantial range of bias current and magnetic flux. For operation in a flux-locked feedback circuit, S/sub e/ was 6 x 10/sup -32/ J/Hz at 1 kHz.

• Research Organization: National Bureau of Standards, Electromagnetic Technology Division, Boulder, Colorado 80303
• OSTI ID: 5262597
• Journal Information: Appl. Phys. Lett.; (United States), Journal Name: Appl. Phys. Lett.; (United States) Vol. 49:17; ISSN APPLA
• Country of Publication: United States
• Language: English

Related Subjects

420201* -- Engineering-- Cryogenic Equipment & Devices
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ELECTRONIC EQUIPMENT
ELEMENTS
EQUIPMENT
FABRICATION
FLUXMETERS
MEASURING INSTRUMENTS
METALS
MICROWAVE EQUIPMENT
NIOBIUM
NOISE
OPERATION
PERFORMANCE
SQUID DEVICES
SUPERCONDUCTING DEVICES
TESTING
TRANSITION ELEMENTS