Low T_c Josephson Tunnel Junctions and their Devices

Abstract

In the present paper we review, in brief, the various fabrication processes, materials used and their applications. We further discuss in some more detail about the practical devices taken one each from the analog and digital circuits. In the field of analog circuits we discuss about the Josephson voltage standard as an example. Where as in the field of digital application we discuss about the Josephson circuits as synchronous switches.

Indexing terms:

• Josephson tunnel junction
• Superconducting devices
• Voltage standard
• Switches

Additional information

Notes on contributors

V N Ojha

Vijay Narain Ojha was born in Ajmer on 9th September, 1958. He received his BSc and MSc (Physics) from Rajasthan University in 1977, 1979 respectively. In 1981 and 1987 M Phil, and Ph D (Physics) from Delhi University. Since November, 1982 he is working as Scientist in the National Physical Laboratory, India. He has published more than 80 research papers in the various national, international journals and conferences in the fields of semiconductors, superconductors and their related devices and also in the field of metrology and ISO-25. Some of them are well cited by other workers in the field.

He has received honous and awards namely ‘Merit Scroll of A.N. Chatterji Memorial Award’ for outstanding work of 1990 in “High T_c SQUID”. He is the recipient of ‘CSIR Young Scientist Award’ in Physical Sciences in 1992 for his contribution “In high T_c SQUID and in Josephson series array Voltage Standard”. Also he is the ‘Young Scientist Awardee’ of the URSI in 1993 and presented the paper in Kyoto, Japan on “Nb/Al₂0₃/Nb series array as voltage standard and switches”. In 1996, ‘MSI Young Scientist Award’ for the research paper.

He was DAAD Fellow at PTB, Germany for 2 years and worked extensively in the field of the fabrication and precision measurment of the Josephson voltage standard and swtiches. He has been the guest worker at CSIRO, Sydney, Australia and ETL, Tsukuba, Japan.

He has delivered many invited talk in the various organisations and conferences namely: IIT, Kanpur; C-Dot; NPL; CII—NEMA Meet, national conferences in the field of microwaves and lightwaves, quality and calibrations and at ETL, Japan.

He is Fellow of ‘Metrology Society of India’ and ‘Indian Cryogenic Council’. Life member of ‘Material Society of India’; ‘Indian Society of Analytical Scientist’ and ‘Indian Science Congress’.

He has edited three books and was convenor of national and international conference in the field of metrology.