Ultra low noise Nb DC SQUIDs

Author

Voss, R.F. ; Laibowitz, R.B. ; Broers, A.N. ; Raider, S.I. ; Knoedler, C.M. ; Viggiano, J.M.

Author_Institution

IBM Thomas J. Watson Research Center, Yorktown Heights, NY

Volume

17

Issue

1

fYear

1981

fDate

1/1/1981 12:00:00 AM

Firstpage

395

Lastpage

399

Abstract

Electron-beam lithography has been used to produce ultra low noise Nb dc SQUIDs (Superconducting QUantum Interference Devices) with Josephson elements consisting of either small area tunnel junctions or very narrow variable thickness bridges (nanobridges). Detailed voltage noise and transfer function measurements have been made as a function of temperature and flux and current bias. These measurements allow a computation of the intrinsic energy resolution ε vs bias parameters as well as comparison with models of intrinsic SQUID noise. The best ε obtained was of order Planck´s constant h. Moreover, the detailed characteristics of the SQUID voltage noise are in agreement with a small signal analysis that depends only on the current noise in each of the Josephson elements and measurable parameters.

Keywords

Josephson device noise; Current measurement; Interference; Josephson junctions; Lithography; Niobium; Noise measurement; SQUIDs; Superconducting device noise; Superconducting devices; Voltage;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/TMAG.1981.1060901

Filename

1060901