Simulation and Analysis of Superconducting Traveling-Wave Parametric Amplifiers

TL;DR

This paper presents theoretical frameworks for analyzing broadband superconducting traveling-wave parametric amplifiers, focusing on dispersion engineering to enhance gain and reduce size, crucial for quantum-limited readout applications.

Contribution

It introduces two analytical models—coupled-mode equations and FDTD simulations—for understanding and optimizing superconducting traveling-wave parametric amplifiers.

Findings

Dispersion engineering significantly improves amplifier gain.

The models help predict device performance accurately.

The frameworks facilitate design optimization for quantum applications.

Abstract

Superconducting parametric amplifiers have great promise for quantum-limited readout of superconducting qubits and detectors. Until recently, most superconducting parametric amplifiers had been based on resonant structures, limiting their bandwidth and dynamic range. Broadband traveling-wave parametric amplifiers based both on the nonlinear kinetic inductance of superconducting thin films and on Josephson junctions are in development. By modifying the dispersion property of the amplifier circuit, referred to as dispersion engineering, the gain can be greatly enhanced and the size can be reduced. We present two theoretical frameworks for analyzing and understanding such parametric amplifiers: (1) generalized coupled-mode equations and (2) a finite difference time domain (FDTD) model combined with a small signal analysis. We show how these analytical and numerical tools may be used to understand device performance.