We have developed original technology of fabricating super-conducting circuits with small Josephson junctions from the Nb/Al/AlOx/Nb sandwich. The minimum linear size of the junctions can be made as small as 70 nm. The pre-gap leakage current measured in these junctions at low temperature is very low, while the value of the superconductor gap is close to the bulk-Nb value. The circuits fabricated with the help of this technology can be used for single-electron, single-Cooper-pair and Josephson quantum computing devices.

The advantage of the developed technology consists in extending the working frequency of the devices up to one order (due to using the super-conducting material with high value of the energy gap) and in possibility of designing the circuits without stray metallic-layer shadows, which are unavoidable in the traditional shadow evaporation technique.