Virtual Quantum Seminar with VTT Finland

Quantum technologies interest and investments are increasing every year, with a potential to disruptively change information and communication technology with deep impacts in information processing and communications. VTT, the Technical Research Centre of Finland, is one of the leading research, development, and innovation organizations in Europe with expertise in quantum hardware technologies providing both hardware and software solutions.

With decades of experience, VTT has been developing and manufacturing superconducting quantum devices to customers since the 1990s with in-house technologies and cleanroom facilities for R&D, prototyping and small-scale manufacturing. With 2,611 m², Micronova host the largest research cleanroom in the Nordic European countries. Researchers at VTT have developed a fabrication method for superconducting tunnel junctions down to the dimensions of 200 nm using i-line UV lithography, that can be applied to different applications, such as SQUID magnetometers and Josephson parametric amplifiers.

The key element of this process is a sidewall-passivating spacer structure (SWAPS) on the Josephson junctions shaped to reduce low parasitic capacitance and unintended crossline contact between the two superconducting layers. With good reproducibility and uniform junction parameters along a 6” wafer, it is possible to fabricate junctions with critical current density ranging from 30 to 3000 A cm-2 for a wide range of devices applications. SWAPS technique can also potentially be utilized in other tunnel junction applications beyond superconductive electronics.

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