Anisotropy of hole spin qubits in a silicon fin field-effect transistor*

Hole spin qubits in silicon quantum dots have a great potential for scaling up quantum circuits, due to the small footprint of the devices and their industry compatibility.

We investigate hole spin qubits integrated in silicon fin field-effect transistors, which represent today’s industry standard transistor geometry. While our devices feature both industry quality and compatibility, they are fabricated in a flexible way to accelerate their development [Geyer et al., Appl. Phys. Lett. 118, 104004 (2021)]. Recently, we have demonstrated qubit operation above 4K and fast, all-electric gate operations with high fidelity [Camenzind et al., arXiv:2103.07369 (2021)].

Here, we explore the mechanisms of hole-spin driving by mapping out the dependence of the qubit parameters (g-factor, Rabi frequency, dephasing time) on the magnetic field orientation. We identify two distinct driving mechanisms: g-tensor and iso-Zeeman spin resonance [Crippa et al., Phys. Rev. Lett. 120, 137702 (2018)] and alter their contribution by applying the microwave signal to different gate electrodes. The anisotropy of the g-factor and the Rabi frequency is well explained by theory. Further, we identify sweet spots in the magnetic field orientation for fast spin manipulation that maintain a high spin coherence.