Nano-optical control of quantum materials in plasmonic nanocavities

The advancement of quantum photonic technologies relies on the ability to control the degrees of freedom of optically active quantum states. The paradigmatic example of optical control of quantum materials are polariton states, material excitations strongly coupled with intense electromagnetic fields. Plexcitons, excitons strongly coupled to plasmon polaritons, have enjoyed an explosion of recent investigations due their ultra-confined interaction volumes which allow for large Rabi – splittings and persistence of the polariton state at ambient conditions. This robustness, combined with the nanoscopic nature of these cavities, makes them promising platforms for tunable on-demand quantum-photonic devices.

In this presentation, I will show our efforts realizing tunable plexcitons using gap mode plasmons formed between metallic nano-optical probes and template stripped gold substrates. Using commercially available quantum dots, we achieve nanoscopic manipulation of the plexciton emission polarization, showing that simple nanocavity designs can achieve circularly polarized emission with purity approaching 80%. In nanobubbles of monolayer transition metal dichalcogenides (1L-TMDs), we realize plexcitons with highly tunable emission energies, and further show that the nanocavity resonance and exciton energy can be electrostatically controlled in operando, making the TMD nanobubble / gap-mode plasmon potentially a plexcitonic nano-electro-mechanical system. Our results show the power of plasmonic nanocavities to control quantum materials in real time.