Time Domain Design of a Josephson Parametric Amplifier and Comparison with Input Output Theory

TL;DR

This paper introduces a circuit-based design approach for Josephson Parametric Amplifiers that simplifies the design process and reduces time compared to traditional quantum input-output theory, while maintaining accurate performance predictions.

Contribution

The paper presents an alternative circuit model for JPAs, enabling faster design optimization using circuit simulators instead of complex quantum theoretical methods.

Findings

Circuit model closely matches input-output theory results.

Design time is significantly reduced using the circuit-based approach.

Open-source simulators facilitate efficient JPA optimization.

Abstract

Quantum-limited amplifiers, such as Josephson Traveling Wave Parametric Amplifiers (JTWPAs) and Josephson Parametric Amplifiers (JPAs), are essential components in quantum computers. They amplify low-power microwave signals from qubits at the 10 mK stage before further amplification at the 4 K stage using HEMT amplifiers. In JPAs, parametric amplification is based on the nonlinear properties of Josephson Junctions. While JPAs are typically designed and analyzed using input-output theory based on quantum physics, we propose an alternative approach based on an equivalent circuit model of JPAs, implemented using open-source Josephson circuit simulators. We compare the results with those obtained from input-output theory. This method enables the use of circuit optimizers for various objective functions and significantly reduces design time compared to quantum theory-based approaches.