Modeling and Harmonic Balance Analysis of Parametric Amplifiers for Qubit Read-out

TL;DR

This paper presents a method for modeling and analyzing traveling-wave parametric amplifiers with Josephson junctions using harmonic balance, validated by experimental data, to improve qubit read-out in quantum computing.

Contribution

It demonstrates how to model nonlinear inductors with Josephson junctions in circuit simulators and applies harmonic balance analysis for reliable performance prediction.

Findings

Harmonic balance accurately predicts amplifier gain and harmonic power.

Experimental results agree with simulation predictions.

Provides modeling techniques for new parametric amplifier designers.

Abstract

Predicting the performance of traveling-wave parametric amplifiers (TWPAs) based on nonlinear elements like superconducting Josephson junctions (JJs) is vital for qubit read-out in quantum computers. The purpose of this article is twofold: (a) to demonstrate how nonlinear inductors based on combinations of JJs can be modeled in commercial circuit simulators, and (b) to show how the harmonic balance (HB) is used in the reliable prediction of the amplifier performance e.g., gain and pump harmonic power conversion. Experimental characterization of two types of TWPA architectures is compared with simulations to showcase the reliability of the HB method. We disseminate the modeling know-how and techniques to new designers of parametric amplifiers.