The Autler-Townes doublet in a pulse-driven quantum emitter.

If a quantum emitter is strongly driven on resonance by a laser field, its emission spectrum displays the well known Mollow triplet[1]. If on the hand the absorption from the excited state to a third, higher energy level is probed, the resulting absorption spectrum is the Autler-Townes doublet[2]. It was recently shown that when the quantum emitter is instead driven by a periodic pulse sequence, the emission spectrum obtained has strong similarities with the Mollow triplet[3]. It is then natural to ask: What is, in this case, the faith of the Autler-Townes doublet? We find that, for a three-level system in the "ladder" configuration, the absorption from the intermediate energy level to the upper level while the transition between the bottom and intermediate energy levels is driven by a periodic pulse sequence has a structure that is dictated by the pulse sequence. This is the case even when the pulse field is moderately detuned from the transition frequency. We discuss the model describing this system and present results for various system parameters.
[1] B. R. Mollow, Phys. Rev. 188, 1969 (1969).
[2] S. H. Autler and C. H. Townes, Phys. Rev. 100, 703 (1955).
[2] H. F. Fotso et al, Phys. Rev. Lett. 116, 033603 (2016).