In-situ characterization of qubit drive-phase distortions

TL;DR

This paper presents a method to detect and correct phase distortions in qubit control signals using the qubit itself as a probe, significantly improving gate fidelity in trapped ion quantum systems.

Contribution

The authors introduce an in-situ technique for characterizing and compensating phase distortions directly through the qubit, applicable in challenging environments like cryogenic or microscopic setups.

Findings

Three-fold reduction in single-qubit gate error

Achieved state-of-the-art error rate of 1.6(4)×10^{-6} per Clifford gate

Effective correction of amplitude-dependent phase distortions

Abstract

Reducing errors in quantum gates is critical to the development of quantum computers. To do so, any distortions in the control signals should be identified, however, conventional tools are not always applicable when part of the system is under high vacuum, cryogenic, or microscopic. Here, we demonstrate a method to detect and compensate for amplitude-dependent phase changes, using the qubit itself as a probe. The technique is implemented using a microwave-driven trapped ion qubit, where correcting phase distortions leads to a three-fold improvement in single-qubit gate error, to attain state-of-the-art performance benchmarked at $1.6(4)\times 10^{-6}$ error per Clifford gate.