A Depinning Model for Josephson Junction Tuning

TL;DR

This paper presents a depinning model for Josephson junction tuning, providing insights into how tuning techniques affect the junctions' properties and optimizing protocols for better quantum computer manufacturing.

Contribution

It introduces a depinning theory-based model to interpret and optimize Josephson junction tuning processes, linking physical modifications to tuning parameters.

Findings

Depinning theory explains controlled junction tuning.

Tuning protocols can be optimized for better performance.

Model reveals effects on barrier breakdown and qubit energy levels.

Abstract

Building more powerful quantum computers requires manufacturing processes with tight tolerances. To improve the tolerances on Josephson junctions, techniques to fine tune their properties after fabrication have been developed. Understanding how tuning techniques may physically modify the tunnel barrier of a Josephson junction is important and will enable these techniques to be optimised. We develop a model of junction tuning based on depinning theory to interpret a phase diagram of tuning rate. We extract the dependence on temperature, time-varying voltages and oscillation frequency. Using depinning theory we are able to show both why time-varying annealing potentials result in controlled junction tuning and how such protocols can be optimised. We examine how tuning changes the electrical breakdown of barriers and discrepancies between modeled and measured higher energy levels of transmon qubits.