Coherent Control of Two-level Systems with Periodic $N$-Steps Driving Fields
Zhi‐Cheng Shi, Ye‐Hong Chen, Wei Yang Qin, Yan Xia, X. X. Yi, Shi-Biao Zheng, Franco Nori
Abstract
In this work, we derive the exact solutions of the dynamical equation, which can describe all two-level Hermitian systems driven by periodic $N$-steps driving fields. The solutions are a set of quasi-periodic functions, and the expressions of the amplitudes and phases are obtained in the frequency-domain. Particularly, we develop a general formalism for the effective Hamiltonian without any approximations, and give the validity range according to the transition probability of the micromotion operator. With the guidance of the exact solutions and the effective Hamiltonian, we find that the coherent destruction of tunneling phenomenon, the resonance phenomenon, and the beat-frequency phenomenon can emerge in this system. Finally, some applications are demonstrated in quantum information processing by periodic $N$-steps driving fields.