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arXiv · 2602.09913

Disentangling orbital and confinement contributions to $g$-factor in Ge/SiGe hole quantum dots

L. Sommer·I. Seidler·F. J. Schupp·S. Paredes·N. W. Hendrickx·L. Massai·K. Tsoukalas·A. Orekhov·E. G. Kelly·S. W. Bedell·G. Salis·M. Mergenthaler·P. Harvey-Collard·A. Fuhrer·T. Ihn
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Abstract

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.

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L. Sommer, I. Seidler, F. J. Schupp, S. Paredes, N. W. Hendrickx, L. Massai, K. Tsoukalas, A. Orekhov, E. G. Kelly, S. W. Bedell, G. Salis, M. Mergenthaler, P. Harvey-Collard, A. Fuhrer, T. Ihn. 2026-02-10. Disentangling orbital and confinement contributions to $g$-factor in Ge/SiGe hole quantum dots. https://doi.org/10.1021/acs.nanolett.6c00999

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