Noise in DC SQUIDS with Nb/Al-oxide/Nb Josephson junctions

Author

Cromar, M.W. ; Beall, J.A. ; Go, Diane ; Masarie, K.A. ; Ono, R.H. ; Simon, R.W.

Author_Institution

Nat. Bur. of Stand., Boulder, CO, USA

Volume

25

Issue

2

fYear

1989

fDate

3/1/1989 12:00:00 AM

Firstpage

1005

Lastpage

1007

Abstract

The authors have developed a process which incorporates very-high-quality Nb/Al-oxide/Nb Josephson junctions. The junctions had low subgap conductance, yielding V_m greater than 50 mV for critical current densities of 1000 A/cm². Low-inductance SQUIDS (superconducting quantum interference devices) made with these junctions were apparently free from junction conductance fluctuations, at least for frequencies above 1 Hz. A correlation between low leakage junctions and low noise from critical current fluctuations was observed. The SQUIDS exhibited flux noise with an unusual frequency dependence of currently unknown origin

Keywords

Josephson effect; SQUIDs; aluminium compounds; critical current density (superconductivity); niobium; Nb-AlO_x-Nb; SQUIDS; critical current densities; flux noise; frequency dependence; junction conductance fluctuations; low leakage junctions; noise; subgap conductance; Critical current; Critical current density; Fluctuations; Frequency; Interference; Josephson junctions; Niobium; SQUIDs; Superconducting device noise; Superconducting devices;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/20.92458

Filename

92458