Switching plasmonic nanogaps between classical and quantum regimes

Quantum plasmonics is the study of quantum properties of light and its interaction with matter at the nanoscale. While intriguing, they are difficult to regulate on account of the lack of proper surface spaces to reversibly actuate sub-1 nanometer gaps. In the field of extreme nanophotonics, researchers have shown how nanogap plasmons can support reliable field enhancements to provide unique opportunities to access a single molecule for strong coupling, and a single atom for quantum catalysis. In a new report now published on Science Advances, Chi Zhang and a team of scientists in physics, science and technology in Wuhan, China, showed that supramolecular systems made of oligoamide sequences can reversibly switch gap plasmons of gold nanoparticles between classical and quantum tunneling regions through supramolecular interactions. The outcomes showed detailed plasmon shift near the quantum tunneling limit to fit well with classical and quantum-corrected models. The team noted how plasmonic hot electronic tunneling in quantum tunneling regions increased conductance in the nanogaps to form a promising prototype of optical tunable, quantum plasmonic nanodevices across the classical and quantum regimes.