Fabrication of low-loss Josephson parametric devices

TL;DR

This paper reports the fabrication and characterization of low-loss Josephson parametric devices with record internal quality factors exceeding 10^5, advancing superconducting quantum technology capabilities.

Contribution

The work demonstrates the fabrication of Josephson parametric devices with significantly improved internal quality factors, surpassing previous benchmarks in the GHz frequency range.

Findings

Achieved internal quality factors >10^5 in Josephson parametric devices.

Confirmed high $Q_{int}$ by analyzing squeezed vacuum states.

Devices enable high-performance quantum circuits.

Abstract

Superconducting circuits incorporating Josephson elements represent a promising hardware platform for quantum technologies. Potential applications include scalable quantum computing, microwave quantum networks, and quantum-limited amplifiers. However, progress in Josephson junction-based quantum technologies is facing the ongoing challenge of minimizing loss channels. This is also true for parametric superconducting devices based on nonlinear Josephson resonators. In this work, we report on the fabrication and characterization of low-loss Josephson parametric devices operated in the GHz frequency range, showing record internal quality factors. Specifically, we achieve internal quality factors $Q_\mathrm{int}$ significantly exceeding $10^5$ for both Josephson parametric converters and Josephson parametric amplifiers in the single-photon regime by fitting the scattering data. We confirm the extracted $Q_\mathrm{int}$ values by analyzing purity of squeezed vacuum states generated by these devices. These low-loss devices mark a significant step forward in realizing high-performance quantum circuits, enabling further advancements in superconducting quantum technologies.