Cryogenic current comparator bridge for quantum Hall resistance ratio measurements

Author

Kleinschmidt, P. ; Williams, J.M. ; Fletcher, N.E. ; Janssen, T.J.B.M.

Author_Institution

Nat. Phys. Lab., Teddington, UK

Volume

149

Issue

6

fYear

2002

Firstpage

302

Lastpage

304

Abstract

A cryogenic current comparator (CCC) bridge for quantum Hall resistance ratio measurement has been constructed. Compared to previous CCC systems at the National Physical Laboratory, UK, the new system differs in two aspects. Firstly, it uses a type-II CCC, i.e. the ratio windings are on the outside and the detection winding is on the inside. This has the advantage that the CCC can be made very compact and fits into a standard storage Dewar. Secondly, the bridge electronics uses a digital servo and the SQUID feedback loop is disabled during current reversals. The overall relative measurement uncertainty of the system is of the order of 10^-9.

Keywords

SQUIDs; bridge instruments; circuit feedback; cryogenics; current comparators; electric resistance measurement; measurement standards; measurement uncertainty; quantum Hall effect; servomechanisms; windings; He; SQUID feedback loop; cryogenic current comparator bridge; current reversals; digital servo bridge electronics; exterior ratio windings; interior detection winding; quantum Hall effect; quantum Hall resistance ratio measurements; relative system measurement uncertainty; storage Dewar fitting device; superconducting quantum interference devices; type-II CCC bridge;

fLanguage

English

Journal_Title

Science, Measurement and Technology, IEE Proceedings -

Publisher

iet

ISSN

1350-2344

Type

jour

DOI

10.1049/ip-smt:20020758

Filename

1176534