  Landau-Zener-Stuckelberg interferometry has been extensively investigated in
quantum two-level systems, with particular interests on artificial system such
as superconducting flux qubits. With increasing the driving field amplitude,
more energy levels will be involved into the quantum evolution, which results
in population inversion and many interesting interference patterns. These
interference patterns can be used to obtain the parameters characterizing the
system and probe dephasing mechanisms of the qubit. Most recently, experiments
have been extended to the regime with higher-frequency and larger-amplitude
driving field, in which the interference pattern exhibited more complicated
characteristics. In this article, we give a universal description of the
characteristics observed in both low-frequency and high-frequency regimes.
Besides explaining the already observed experimental results, our theoretical
model predicted many interesting phenomenon, which can be demonstrated by
future experiments.
