Fabrication of high-quality Josephson junctions for quantum computation using a self-aligned process

Quantum computers are believed to have the potential to perform certain tasks much better than conventional computers. Recently, very promising results have been demonstrated with superconducting devices based on Josephson junctions. The quality of the Josephson junctions plays an important role in determining the coherence time of superconducting quantum bits, and hence the viability of superconducting quantum computers. We have developed a self-aligned process for the fabrication of Nb-based Josephson devices. A UVN-30 negative-tone resist is used for both electron beam and photo-lithography. Very high quality Josephson junctions with sizes as small as 0.15 × 0.15 µm2 have been made. This process has a turn around time of 4-5 days which makes it much easier to study different factors affecting the quality of Josephson junctions.