Dynamical Acoustic Control of Resonance Fluorescence from a Strongly Driven Two-Level System

Resonance fluorescence from a single two-level system is a cornerstone of quantum optics. In the strong driving regime, its emission spectrum exhibits the iconic Mollow triplet, with each spectral component corresponding to a transition between distinct atom-photon dressed states. Here, we experimentally study the resonance fluorescence spectrum under a novel driving configuration in which a second gigahertz-frequency field drives the Rabi transition between two atom-photon dressed states. Our experiment is performed on a single semiconductor quantum dot strongly driven by a laser and a surface acoustic wave. We observe emission spectra that are significantly altered from the standard Mollow triplet, including the dynamical cancellation of resonance fluorescence at the central emission frequency. These spectra are explained by a theoretical model that incorporates the hybridization of the two-level system, the optical field, and the acoustic field. Motivated by this model, we experimentally validate the condition for optimal cooling of acoustic phonons in an emitter-optomechanical system. Our results offer new insights into the quantum interactions among single two-level systems, optical fields, and acoustic fields in the strong driving limit, with important applications in nonclassical acoustic state generation, quantum transduction, and quantum sensing of thermal motions.