Fidelity of strongly driven electric dipole spin resonance

Coherent control of a single spin confined in a quantum dot (QD) by the microwave electric field (electric dipole spin resonance; EDSR) is an active field of recent research. One of the required mechanisms to couple the orbital motion to the spin degree of freedom is to utilize the slanting magnetic field [1]. J. Yoneda et al.[2] had reported EDSR with a large Rabi frequency up to 100 MHz by optimizing the design of the micro-magnet as well as inducing larger power of microwave. In the largest achievable microwave amplitude, the Rabi frequency is saturated from the expected linear dependence with the microwave amplitude and the fidelity of the Rabi oscillation becomes degraded. Possible origin of this saturation is the non-parabolicity of the confinement potential [3]. In this report, we study the effect of the noise by strongly-driven orbital motion on the fidelity of the spin. In particular, the first (second)-order spin-orbital coupling induces enhanced spin-relaxations (decoherence) with increasing microwave amplitude.
[1] Y. Tokura, et al., Phys. Rev. Lett. 96, 047202 (2006). [2] J. Yoneda, et al., Phys. Rev. Lett. 113, 267601 (2014). [3] Y. Tokura, et al., JPS Conf. Proc. 1, 012022 (2014).