Visualising adiabatic transitions in the topology of plasmonic vortex networks

When hybrid light-matter states such as surface plasmon polaritons contain non-zero (fractional) orbital angular momentum (OAM), their wave function as well as photonic spin density distribution contain complex networks of singularities. In this talk, I will discuss how experimentally visualising the adiabatic propagation through OAM parameter space reveals intriguing consequences of the 2D cylindrical symmetry of the system’s eigenfunctions: Instead of the generic pair creation/annihilation of plasmonic vortices, non-local vortex interactions occur, leading to the increase of the state’s topological index via the creation of vortices at the boundaries of the system.

In addition to realising Hilbert’s hotel paradox of transfinite numbers in plasmonic fields, such as dynamically tuneable configuration of vortex sites in hybrid light-matter states allows for tailored nanoscale interactions in analog systems such as 2D exciton polaritons, where the added spin-valley coupling can lead to novel concepts in valleytronic metasurfaces.