Variability of hole spin qubits in planar Germanium

TL;DR

This study investigates the variability in charge and spin properties of hole spin qubits in Germanium heterostructures, highlighting the impact of interface quality and providing strategies to optimize qubit performance for scalable quantum computing.

Contribution

The paper introduces a detailed numerical analysis of charge and spin variability in Ge hole spin qubits, offering new insights into interface effects and optimization strategies.

Findings

Charge property variability is moderate.

Spin property variability is significant.

Guidelines for minimizing variability are proposed.

Abstract

Hole spin qubits in Ge/GeSi heterostructures benefit from the clean environment of epitaxial interfaces and from the intrinsic spin-orbit coupling that enables efficient electrical control, which makes them promising candidates for quantum computation. However, spin-orbit coupling also enhances the sensitivity to electrical disorder, potentially increasing variability. In this work, we perform numerical simulations in a realistic device geometry to quantify the variability of the charge and spin properties of Ge qubits induced by charge traps at the SiGe/oxide interfaces. We show that while the variability of charge properties remains moderate, spin properties (g-factors and Rabi frequencies) show significant dispersion. We explore the implications of this variability for large-scale architectures, and provide guidelines to minimize variability both in terms of interface quality requirements and optimal operation strategies.