  Strong driving of quantum systems opens opportunities for both controlling
and characterizing their states. For theoretical studying of these systems
properties we use the rate-equation formalism. The advantage of such approach
is its relative simplicity. We used the formalism for description of a
two-level system (TLS) with further expanding it on a case of a multi-level
system. Obtained theoretical results have good agreement with experiments. The
presented approach can also be considered as one more way to explore properties
of quantum systems and underlying physical processes such as for instance
Landau-Zener-Stuckelberg-Majorana transitions and interference.
