Spin dynamics in a strongly driven system: Very slow Rabi oscillations

We consider joint effects of tunneling and spin-orbit coupling on driven by electric field spin dynamics in a double quantum dot with a multilevel resonance scenario. We demonstrate that tunneling plays the crucial role in the formation of the Rabi-like spin-flip transitions. In contrast to the linear behavior for weak electric fields, the spin-flip rate becomes much smaller than expected for the two-level model and shows oscillating dependence on the driving field amplitude in stronger fields. In addition, the full spin flip is very difficult to achieve in a multilevel resonant system. These two effects have a similarity with the Zeno effect of slowing down the dynamics of an observable by its measurement. As a result, spin manipulation by electric field becomes much less efficient than expected.