Spin qubits are typically operated in the lowest orbital of a quantum dot to minimize interference from nearby states. In valence-band hole systems, strong spin-orbit coupling links spin and orbital degrees of freedom, strongly influencing the hole g-factor, a key parameter for qubit control. We investigate the out-of-plane g-factor in Ge quantum dots using excitation (single-particle) and addition (many-body) spectra. Excitation spectra allow us to distinguish the pure Zeeman g-factor from orbital contributions to the magnetic field splitting of states despite the strong spin-orbit coupling. This distinction clarifies discrepancies between g-factors extracted with the two methods, for different orbital states and different hole numbers. Furthermore, we find gate-tunability of g-factors at the level of 15%, highlighting its relevance for all-electric qubit manipulation.
@article{arxiv.2602.09913,
title = {Disentangling orbital and confinement contributions to $g$-factor in Ge/SiGe hole quantum dots},
author = {L. Sommer and I. Seidler and F. J. Schupp and S. Paredes and N. W. Hendrickx and L. Massai and K. Tsoukalas and A. Orekhov and E. G. Kelly and S. W. Bedell and G. Salis and M. Mergenthaler and P. Harvey-Collard and A. Fuhrer and T. Ihn},
journal= {arXiv preprint arXiv:2602.09913},
year = {2026}
}