Electron-beam annealing of Josephson junctions for frequency tuning of quantum processors

TL;DR

This paper introduces an electron-beam annealing method to locally tune Josephson junctions in superconducting qubits, improving frequency control and reducing collisions for scalable quantum processors.

Contribution

It presents a novel electron-beam annealing technique for precise frequency tuning of Josephson junctions, compatible with standard fabrication processes.

Findings

Able to both increase and decrease junction barrier resistance

Improved wafer-scale frequency targeting

Maintained coherence performance after tuning

Abstract

Superconducting qubits are a promising route to achieving large-scale quantum computers. A key challenge in realising large-scale superconducting quantum processors involves mitigating frequency collisions. In this paper, we present an approach to tuning fixed-frequency qubits with the use of an electron beam to locally anneal the Josephson junction. We demonstrate the ability to both increase and decrease the junction barrier resistance. The technique shows an improvement in wafer scale frequency targetting by assessing the frequency collisions in our qubit architecture. Coherence measurements are also done to evaluate the performance before and after tuning. The tuning process utilises a standard electron beam lithography system, ensuring reproducibility and implementation by any group capable of fabricating these Josephson junctions. This technique has the potential to significantly improve the performance of large-scale quantum computing systems, thereby paving the way for the future of quantum computing.