In-situ control of hole-spin driving mechanisms

TL;DR

This paper demonstrates in-situ control over the dominant electric-dipole spin resonance mechanisms in hole-spin qubits, enabling switching between g-factor modulation and wavefunction displacement to optimize qubit performance.

Contribution

It introduces a method to tune the primary EDSR driving mechanism in hole-spin qubits via gate electrode control, providing new insights into spin manipulation.

Findings

Distinct angular dependencies of g-factor and Rabi frequency were observed.

Switching between g-factor modulation and wavefunction displacement was achieved.

The in-situ tunability enhances understanding and control of spin-qubit dynamics.

Abstract

Hole-spin qubits enable fast, all-electrical spin manipulation through electric-dipole spin resonance (EDSR), arising from two microscopic mechanisms rooted in their intrinsically strong spin-orbit interaction. Depending on how the electric field acts on the quantum dot, the spin can be driven either by a modulation of its g-factor or by a displacement of the wavefunction. Here, we demonstrate in-situ control over the dominant EDSR driving mechanism of a hole-spin qubit in a silicon fin field-effect transistor by applying microwave signals to two different gate electrodes, thereby tuning the orientation of the local electric field. We measure the effective g-factor, its electrical tunability, and the Rabi frequency as functions of magnetic-field orientation. Their distinct angular dependencies, analyzed using a g-matrix formalism, allow us to identify the underlying driving processes and track their relative contributions for different drive configurations. By selecting the drive electrode, we can switch from a regime dominated by g-factor modulation to one with a strong contribution from wavefunction displacement. This in-situ tunability provides direct experimental access to both spin-driving mechanisms and offers a route toward optimized spin-qubit performance.