Fidelity of Electric Dipole Spin Resonance in nonlinear system

Electric dipole spin resonance (EDSR) is a versatile technique for the coherent manipulation of electron spins confined in quantum dots (QDs) using a microwave electric field. Here, we theoretically discuss EDSR in systems with intrinsic or synthetic spin-orbit interaction (SOI) of an electron or hole spin confined in a QD, particularly when the microwave amplitude is large. In a system with linear-in-momentum SOI or a linear magnetic field gradient, the spin in a parabolic confinement potential exhibits ideal Rabi oscillations at the resonant frequency in the lowest-order perturbation case. However, for SOI with higher-order momentum terms or in certain nonlinear cases, residual orbital-spin couplings remain even in the lowest order. Consequently, the Rabi frequency exhibits nonlinear dependence on the applied microwave amplitude, and resulting in reduced spin fidelity.