Giant Purcell broadening and Lamb shift for DNA-assembled near-infrared quantum emitters

TL;DR

This study demonstrates that DNA-assembled plasmonic nanocavities can induce giant Purcell effects and Lamb shifts in near-infrared quantum emitters, advancing quantum nanophotonics and single-molecule emission control.

Contribution

It introduces a scalable DNA origami method to engineer plasmonic environments, achieving large Purcell factors and Lamb shifts comparable to scanning tip experiments.

Findings

Commercial fluorophores experience giant Purcell factors and Lamb shifts.

Cavity-mediated fluorescence can be far detuned from the zero-phonon-line.

Emission linewidth can be dominated by excited state lifetime, enabling indistinguishable photon emission.

Abstract

Controlling the light emitted by individual molecules is instrumental to a number of novel nanotechnologies ranging from super-resolution bio-imaging and molecular sensing to quantum nanophotonics. Molecular emission can be tailored by modifying the local photonic environment, for example by precisely placing a single molecule inside a plasmonic nanocavity with the help of DNA origami. Here, using this scalable approach, we show that commercial fluorophores experience giant Purcell factors and Lamb shifts, reaching values on par with those recently reported in scanning tip experiments. Engineering of plasmonic modes enables cavity-mediated fluorescence far detuned from the zero-phonon-line (ZPL) - at detunings that are up to two orders of magnitude larger than the fluorescence linewidth of the bare emitter and reach into the near-infrared. Our results evidence a regime where the emission linewidth is dominated by the excited state lifetime, as required for indistinguishable photon emission, baring relevance to the development of nanoscale, ultrafast quantum light sources and to the quest toward single-molecule cavity-QED. In the future, this approach may also allow to design efficient quantum emitters at infrared wavelengths, where standard organic sources have a reduced performance.