Digital Predistortion of Power Amplifiers for Quantum Computing

TL;DR

This paper proposes using digital predistortion (DPD) to linearize power amplifiers in quantum computers, improving signal fidelity without excessive power back-off, thus enhancing quantum gate performance.

Contribution

It introduces a DPD method tailored for quantum computing RF channels, demonstrating improved fidelity through numerical analysis.

Findings

DPD enhances qubit control signal fidelity

Linearization reduces nonlinear distortion effects

Numerical results show improved quantum gate performance

Abstract

Power amplifiers (PA) are essential for microwavecontrolled trapped-ion and semiconductor spin based quantum computers (QC). They adjust the power level of the control signal and therefore the processing time of the QC. Their nonlinearities and memory effects degrade the signal quality and, thus, the fidelity of qubit gate operations. Driving the PA with a significant input power back-off reduces nonlinear effects but is neither power-efficient nor cost-effective. To overcome this limitation, this letter augments the conventional signal generation system applied in QCs by digital predistortion (DPD) to linearize the radio frequency (RF) channel. Numerical analysis of the qubit behavior based on measured representative control signals indicates that DPD improves its fidelity.