Spin qubits in germanium gate-defined quantum dots have made considerable progress within the last few years, partially due to their strong spin-orbit coupling and site-dependent g-tensors. While this characteristic of the g-factors removes the need for micromagnets and allows for the possibility of all-electric qubit control, relying on these g-tensors necessitates the need to understand their sensitivity to the confinement potential that defines the quantum dots. Here, we demonstrate a S−T_ qubit whose frequency is a strong function of the voltage applied to the barrier gate shared by the quantum dots. We find a g-factor that can be approximately increased by an order of magnitude adjusting the barrier gate voltage only by 12 mV. We attribute the strong dependence to a variable strain profile in our device. This work not only reinforces previous findings that site-dependent g-tensors in germanium can be utilized for qubit manipulation, but reveals the sensitivity and tunability these g-tensors have to the electrostatic confinement of the quantum dot.
@article{arxiv.2311.10188,
title = {Gate modulation of the hole singlet-triplet qubit frequency in germanium},
author = {John Rooney and Zhentao Luo and Lucas E. A. Stehouwer and Giordano Scappucci and Menno Veldhorst and Hong-Wen Jiang},
journal= {arXiv preprint arXiv:2311.10188},
year = {2023}
}