Controllable single-spin evolution at subharmonics of electric dipole spin resonance enhanced by four-level Landau-Zener-Stückelberg-Majorana interference

Subharmonics of electric dipole spin resonance (EDSR) mediated by Landau-Zener-St\"uckelberg-Majorana tunneling transitions are studied numerically and analytically in a Zeeman-split four-level system with strong spin-orbit coupling that can be realized, for example, in a GaAs-based double quantum dot in a single-hole regime. The spin qubit is formed in one of the dots and the second dot is used as an auxiliary element to enhance functionality of the spin qubit. In particular, it is found that the spin rotation rate can be essentially enhanced due to the tunnel coupling with the auxiliary dot on both the main EDSR frequency and at its high subharmonics allowing the coherent spin $\ensuremath{\pi}$ rotations on a 10-ns timescale. Spin manipulation on high subharmonics is promising for new time-efficient schemes of the spin control and readout in qubit devices operating at high magnetic fields where the main harmonic is inaccessible due to hardware limitations.