Modelling Realistic Multi-layer devices for superconducting quantum electronic circuits

TL;DR

This paper introduces a comprehensive 3D numerical model for multilayer superconducting devices, improving accuracy and flexibility in designing quantum circuits with enhanced control and performance.

Contribution

The authors develop a novel numerical model that accurately simulates multilayer superconducting devices without layout approximations or material limits.

Findings

Multilayer films improve control over critical currents and energy gaps.

Multilayer nanobridge junctions enhance qubit anharmonicity.

Multilayer structures enable better analysis of proximity effects in microwave circuits.

Abstract

In this work, we present a numerical model specifically designed for 3D multilayer devices, with a focus on nanobridge junctions and coplanar waveguides. Unlike existing numerical models, ours does not approximate the physical layout or limit the number of constituent materials, providing a more accurate and flexible design tool. We calculate critical currents, current phase relationships, and the energy gap where relevant. We validate our model by comparing it with published data. Through our analysis, we found that using multilayer films significantly enhances control over these quantities. For nanobridge junctions in particular, multilayer structures improve qubit anharmonicity compared to monolayer junctions, offering a substantial advantage for qubit performance. For coated multilayer microwave circuits it allows for better studies of the proximity effect, including their effective kinetic inductance.