Evolution of HTS Josephson junctions and their application at ISTEC and SUSTERA
The evolution of HTS Josephson junction technology and its application during the last over twenty years is reviewed, mostly focusing on that at ISTEC and SUSTERA. The fabrication technology of oxide multilayer and ramp-edge Josephson junctions was much advanced during the decade from 1995 to 2005 to develop HTS single flux quantum (SFQ) devices. Although the development of SFQ devices resulted in only demonstration of small-scale circuits and a sampler system mainly due to a rather large critical current spread of HTS Josephson junctions, the developed multilayer and the junction technology was applied to fabrication of multilayer HTS SQUIDs with high resistance to external magnetic field. Using these HTS SQUIDs, a variety of systems, in particular, those for field use such as TEM systems for exploration or monitoring of natural resources and a nondestructive testing system for infrastructure have been developed and demonstrated. HTS SQUIDs can be now stably operated in various fields, for example, on the ground, in a borehole, and on an expressway. The application field of HTS SQUIDs is expected to further expand in the near future.
The History of SQUIDs Abstract
The SQUID in its various forms has been a mainstay in many application arenas for more than 50 years. This presentation will concentrate on the unique discovery and development of SQUIDs at the Ford Motor Company in the 1960’s from a first-person perspective.
The presentation will include:
- Discussion of critical prior developments that led to the first realization of macroscopic quantum interference in superconductors
- Experiments leading to the development of dc, rf, and resistive SQUIDs
- Experimental technologies available at that time (in contrast to today)
- Innovative improvement and expansion of SQUID technology since the 1960’s