Fig. 2: Hole qubit EDSR Rabi frequency f_π calculated from the k.p model under uniform uniaxial strain.

The angles of B and \({\tilde{{\bf{E}}}}_{{\rm{ac}}}\) w.r.t. the [100] axis are denoted by θ and ϕ, respectively. At F_z = 1.5 MV/m (a–d) and F_z = 15 MV/m (e–h) top-gate fields, with uniaxial strain assumption, f_π is evaluated for a smaller dot first, a, e a_d = 20 nm, ∣B∣ = 200 mT, b, f a_d = 20 nm, ∣B∣ = 670 mT; and then for a larger dot, c, g a_d = 45 nm, ∣B∣ = 200 mT, d, h a_d = 45 nm, ∣B∣ = 670 mT. Here, a_d signifies the dot radius, and ∣B∣ denotes the magnitude of the applied magnetic field. As suggested by the color bars, the EDSR Rabi frequency improves with increasing the dot radius as well as the applied B strength. f_π(θ, ϕ) largely follows the trend of the dot product \({\bf{B}}\cdot {\tilde{{\bf{E}}}}_{{\rm{ac}}}\). As shown in (d, h), for a large dot at a higher magnetic field, the strong orbital vector potential terms cause the f_π(θ, ϕ) trend to deviate from the dot product \({\bf{B}}\cdot {\tilde{{\bf{E}}}}_{{\rm{ac}}}\) relation. The microwave drive amplitude is given by E_ac = 10 kV/m.