In-operando microwave scattering-parameter calibrated measurement of a Josephson travelling wave parametric amplifier

TL;DR

This paper introduces an in-operando microwave calibration method to accurately measure and analyze the S-parameters of a Josephson traveling wave parametric amplifier, improving understanding of its reflective behavior during operation.

Contribution

It presents a novel microwave calibration technique for in-operando S-parameter extraction of a Josephson TWPA, enabling precise characterization of reflections during operation.

Findings

Reflections at the TWPA can be accurately quantified during operation.

In-operation performance aligns with off-state measured S-parameters.

Calibration enhances understanding of impedance matching in TWPAs.

Abstract

Superconducting travelling wave parametric amplifiers (TWPAs) are broadband near-quantum limited microwave amplifiers commonly used for qubit readout and a wide range of other applications in quantum technologies. The performance of these amplifiers depends on achieving impedance matching to minimise reflected signals. Here we apply a microwave calibration technique to extract the S-parameters of a Josephson junction based TWPA in-operando. This enables reflections occurring at the TWPA and its extended network of components to be quantified, and we find that the in-operation performance can be well described by the off-state measured S-parameters.