Anharmonic Quantum Oscillator as a Model of Resonant Optics

The speci c features of the theory of resonant interactions of electromagnetic coherent elds with an anharmonic oscillator, as compared to the case of a multilevel atom, are highlighted. It is shown that within the framework of the local approach - the algebraic resonance perturbation theory - it is possible to account for the requirements of the global approach of the theory of open quantum systems. Based on the auxiliary model of the «internal nonlinearity» of the anharmonic oscillator, the possible conditions for the resonance of a coherent wave with an anharmonic oscillator involving the absorption of a single photon are analyzed.