Fano-like interference induced modification of Autler-Townes doublet spectrum via phase-dependent superposition of atomic states

Abstract

A four-level atomic model is proposed to exhibit the evolution of Fano-like interference effect in the spontaneous emission spectrum of Autler-Townes (AT) doublet when the atom is initially prepared in the phase-dependent superposition of quantum states. By using this model, phase-dependent generation of a narrow spectral line within the AT-doublet is predicted. This feature is shown to be modified by the AT-peak-splitting effect. In addition, it has been also shown that the latter may be accompanied by an anomalous peak shifting effect, which is found to be obtained in a typical phase-coherent atomic ensemble or phaseonium under consideration. As a whole, the emission spectrum can be obtained with three peaks instead of two peaks associated with a sharp spectral hole as a consequence of the emergence of asymmetric Fano-like resonance. This is the most interesting outcome of the present study.