Microscopic effects in the manipulation of hole spin qubits and hybrid devices
Invited talk given at ISTA in May 2025
In recent years, there has been a growing interest in using hole spins in silicon and germanium for quantum information processing. One reason for this is the strong spin-orbit interaction present in the valence band of these materials, which allows for versatile interactions with classical and quantum electric fields. As a result, there have been demonstrations of fast electrical manipulation of hole spin qubits [1, 2], large coherence times at tailored sweet spots [3]. Besides, hole spins in Ge have demonstrated superconducting gaps due to the proximity effect with superconductors, opening a new avenue towards topological and hybrid quantum computation. In this talk, I will go beyond the simple models for electrical spin manipulation in semiconductor quantum dots, showing that microscopic effects, realistic electrostatics [4], and strain [5] heavily affect the performance of hole spin qubits, allowing fast manipulation and strong coupling to cavity photons [6, 7]. Finally, I will cover the superconducting proximity effect with Ge holes, showing unusual superconducting correlations can arise due to the spin-orbit interactions of holes [8].
[1] G. Scappucci et al., Nat. Rev. Mater 6, 926-943 (2021). [2] N. Hendrickx et al., Nature 591, 580-585 (2021). [3] N. Piot et al., Nat. Nano. 17, 1072-1077 (2022). [4] B. Martínez. et al., Phys. Rev. B 106, 235426 (2022). [5] J. C. Abadillo-Uriel et al., Phys. Rev. Lett. 131, 097002 (2023). [6] Michal et al., Phys. Rev. B 107, L041303 (2023). [7] Yu et al., Nat. Nano. 18, 741-746 (2023). [8] M. Pino et al., arxiv: 2501.00088