Electrical spin driving by $g$-matrix modulation in spin-orbit qubits

TL;DR

This paper investigates the physical mechanisms behind electrically driven spin rotations in spin-orbit qubits, demonstrating a $g$-matrix formalism that distinguishes different contributions to the Rabi frequency, applicable to various qubit types.

Contribution

It introduces a $g$-matrix formalism that captures and discriminates multiple mechanisms of spin driving in spin-orbit qubits, enhancing understanding of their physical origins.

Findings

Identified two mechanisms contributing to spin rotations: $g$-factor modulation and another not associated with Zeeman energy.

Measured angular dependence of Rabi frequency and anisotropy of hole $g$-factors.

Validated the $g$-matrix approach as a general tool for analyzing spin-orbit qubits.

Abstract

In a semiconductor spin qubit with sizable spin-orbit coupling, coherent spin rotations can be driven by a resonant gate-voltage modulation. Recently, we have exploited this opportunity in the experimental demonstration of a hole spin qubit in a silicon device. Here we investigate the underlying physical mechanisms by measuring the full angular dependence of the Rabi frequency as well as the gate-voltage dependence and anisotropy of the hole $g$-factors. We show that a $g$-matrix formalism can simultaneously capture and discriminate the contributions of two mechanisms so far independently discussed in the literature: one associated with the modulation of the $g$ factors, and measurable by Zeeman energy spectroscopy, the other not. Our approach has a general validity and can be applied to the analysis of other types of spin-orbit qubits.