Self-assembled $\mathrm{In}\mathrm{Ga}\mathrm{As}$/$\mathrm{Ga}\mathrm{As}$ quantum dots (QDs) are of particular importance for the deterministic generation of spin-photon entanglement. One promising scheme relies on the Larmor precession of a spin in a transverse magnetic field, which is governed by the in-plane $g$ factors of the electron and the valence-band heavy hole. We probe the origin of heavy-hole $g$-factor anisotropy with respect to the in-plane magnetic field direction and uncover how it impacts the entanglement generated between the spin and the photon polarization. First, using polarization-resolved photoluminescence measurements on a single QD, we determine that the impact of valence-band mixing dominates over effects due to a confinement-renormalized cubic Luttinger $q$ parameter. From this, we construct a comprehensive hole $g$-tensor model. We then use this model to simulate the concurrence and fidelity of spin-photon entanglement generation with anisotropic hole $g$ factors, which can be leveraged by tuning the magnetic field angle and the excitation polarization. The results demonstrate that postgrowth control of the hole $g$ factor can be used to improve spin-photon cluster-state generation.

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• Entanglement production
• Magnetic anisotropy
• Optical quantum information processing
• Polarization of light
• Semiconductor quantum optics
• Spin optoelectronics
• III-V semiconductors
• Quantum dots