Heavy-Hole--Light-Hole Mixing and Spin--Photon Coupling in Germanium Flopping-Mode Qubits

Abstract:Intrinsic spin--orbit interaction in germanium provides electrically active flopping-mode qubits without requiring magnetic-field gradients to generate spin--charge hybridization. We study double quantum dots (DQDs) with a multiband Luttinger--Kohn framework that retains heavy-hole (HH) and light-hole (LH) states on equal footing. Modeling vertical confinement with a finite confinement potential along the growth direction brings selected subbands into a regime of appreciable HH--LH mixing. This admixture activates electric-dipole spin-coupling through LH--LH and LH--HH transitions, complementing the conventional HH--HH pseudospin-flip resonance. For the parameter sets considered, these additional channels can produce larger spin--photon figures of merit than the HH--HH transition. HH--LH mixing thus supplies a tunable ingredient for qubit--cavity coupling in germanium hole-spin qubits and extends the operating regimes available to circuit-QED architectures.

Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Quantum Physics (quant-ph)

arXiv:2608.29325 [cond-mat.mes-hall]

(or arXiv:2608.29325v1 [cond-mat.mes-hall] for this version)

https://doi.org/10.48550/arXiv.2608.29325 Focus to learn more arXiv-issued DOI via DataCite (pending registration)

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