Asymmetric YBaCuO interferometers and SQUIDs made with focused electron-beam irradiation junctions

We report the fabrication and testing of compact interferometers operating at temperatures up to 60-80 K. Focused electron-beam irradiation Josephson junctions are made in YBaCuO, and a focused ion beam is used for precise etching of the tracks of superconductor. The SQUID characteristics and the properties of coupled superconducting loops are promising for applications such as comparators for analog/digital converters. Focused ion beam trimming of circuit elements is particularly useful for prototyping devices and for defining the small inductors required in circuits for high temperature operation.