Picocavity-Controlled Subnanometer-Resolved Single-Molecule Fluorescence Imaging and Mollow Triplets

In this article, we address subnanometer resolved fluorescence imaging of single molecule inside a plasmonic picocavity by proposing a semiclassical theory via combining the macroscopic quantum electrodynamics theory and the open quantum system theory. To gain insights into the experimental results [ Nat. Photonics, 2020, 14, 694−699, DOI: 10.1038/s41566-020-0677-y ], we have further equipped this theory with the classical electromagnetic simulation of the picocavity, formed by atomistic cluster-decorated silver STM tip and a silver substrate, and the time-dependent density functional theory calculation of zinc phthalocyanine molecule. Our simulations not only reproduce the fluorescence spectrum and imaging as measured in the experiment, confirming the influence of extreme field confinement afforded by the picocavity, but also predict Rabi oscillation dynamics and Mollow triplets spectrum for moderate laser excitation. Thus, our study highlights the possibility of coherently manipulating the molecular state and exploring quantum optical phenomena with the plasmonic picocavity.