Intermodulation Distortion in a Josephson Traveling Wave Parametric Amplifier

TL;DR

This paper investigates intermodulation distortion in Josephson traveling wave parametric amplifiers, revealing how it affects multiplexed quantum measurements and proposing mitigation strategies to improve fidelity.

Contribution

It characterizes intermodulation distortion effects in these amplifiers and suggests using large detunings to reduce crosstalk in multiplexed quantum readout.

Findings

Intermodulation distortion increases near saturation power.

Crosstalk significantly reduces qubit readout fidelity.

Large detunings mitigate intermodulation effects.

Abstract

Josephson traveling wave parametric amplifiers enable the amplification of weak microwave signals close to the quantum limit with large bandwidth, which has a broad range of applications in superconducting quantum computing and in the operation of single-photon detectors. While the large bandwidth allows for their use in frequency-multiplexed detection architectures, an increased number of readout tones per amplifier puts more stringent requirements on the dynamic range to avoid saturation. Here, we characterize the undesired mixing processes between the different frequency-multiplexed tones applied to a Josephson traveling wave parametric amplifier, a phenomenon also known as intermodulation distortion. The effect becomes particularly significant when the amplifier is operated close to its saturation power. Furthermore, we demonstrate that intermodulation distortion can lead to significant crosstalk and reduction of fidelity for multiplexed readout of superconducting qubits. We suggest using large detunings between the pump and signal frequencies to mitigate crosstalk. Our work provides insights into the limitations of current Josephson traveling wave parametric amplifiers and highlights the importance of performing further research on these devices.