Quantum plasmonics with multi-emitters: application to stimulated Raman adiabatic passage

We construct a mode-selective effective model describing the interaction of the localised surface plasmon polaritons (LSPs) supported by a spherical metal nanoparticle (MNP) with N quantum emitters (QEs) in an arbitrary geometric arrangement. Simplifying previously presented procedures, we develop a formulation in which the field response in the presence of the MNP can be decomposed into orthogonal modes, expanding the Green tensor of the system in the spherical vector harmonics basis and using the generalized global Löwdin orthogonalization algorithm. We investigate the possibility of using the LSPs as mediators of an efficient control of population transfer between two QEs. We show that a Stimulated Raman Adiabatic Passage (STIRAP) configuration allows such a transfer via a decoherence-free dark state for a specific range of angular distances between the QEs, when they are located very close to the MNP. The transfer is otherwise blocked. We explain this blockade by the destructive superposition of all the plasmonic modes.