Tip-enhanced strong coupling spectroscopy and control of a single quantum emitter

By: Kyoung-Duck Park, Molly A. May, Haixu Leng, Jiarong Wang, Jaron A. Kropp, Theodosia Gougousi, Matthew Pelton, Markus B. Raschke

Science Advances (in press)

Optical cavities can enhance and control the light-matter interaction by modifying the local electromagnetic density of states of a quantum emitter. In the nanoscale extension, with the manipulation of quantum emitters via plasmonic cavities in the strong coupling regime, this opens new pathways from opto-electronics to quantum information science. However, conventionally, emitters are placed in static plasmonic cavities which limit the ability to tune the coupling strength or investigate different emitters with the same cavity. Here, we present tip-enhanced strong coupling (TESC) spectroscopy, imaging, and control based on scanning probe microscopy using a plasmonic antenna-tip forming a nano-cavity with the emitter placed on a metallic mirror substrate. We observe plexciton photoluminescence of single quantum dots (QDs) at room temperature with mode splitting up to ~ 163 meV, and anticrossing in the energy spectra of different single QDs over a detuning range of ~100 meV with respect to the plasmonic cavity. In addition, by controlling the tip-sample cavity with sub-nm precision, we reversibly tune the coupling strength through the strong coupling transition. Our approach opens a new regime of nano-cavity quantum electrodynamics with manipulation of the nanoscale quantum light-matter interaction of single emitters at room temperature.