On the importance of nonlocal effects on the description of emitter-plasmon coupling

Plasmonic nanostructures present several characteristics that make them ideal templates for the modification and control of the emission properties of quantum emitters such as organic molecules, fluorescent dyes and quantum dots. State-of-the-art plasmonic architectures strongly enhance and confine light to subwavelength regions, and largely modify the local density of states, on which their interaction with an emitter mainly depends, thus paving new routes for exploring light-matter interactions. Advances in nanotechnology and nanofabrication have recently led to the minimisation of relative dimensions, allowing the design of ultranarrow plasmonic cavities and the precise positioning of emitters inside them. In these situations, however, a description beyond classical electrodynamics is rendered unavoidable, as nonclassical effects such as electron spill-out, tunnelling, and nonlocal screening become relevant [1, 2]. Here we explore the influence of the latter, larger-scale effect, on the coupling of various emitters with canonical plasmonic nanostructures.