Influence of geometric configuration on non-Markovian dynamics and quantum speed limits in a quantum emitter’s spontaneous emission near a multilayer plasmonic nanosphere

Abstract In this study, we investigate a hybrid system consisting of a Quantum Emitter (QE) positioned in close proximity to a spherical, Multilayer plasmonic nanostructure (PNS). Our primary focus is on the QE’s spontaneous emission dynamics. Employing the dyadic Green tensor, we systematically analyze the influence of different geometries and materials on the system’s behavior, with specific emphasis on the Quantum Speed Limit (QSL) and non-Markovian dynamics. Key geometrical parameters explored include the shell thickness of Core/Shell nanostructure (CSNS), core radius, the nanosphere radius, and the QE-PNS spatial separation distance. Both Silver and Gold, two noble metals, are considered for the nanosphere and shell materials. Our findings show that as the QE-PNS separation distance increases, spontaneous emission dynamics shifts from non-Markovian to Markovian regime. Non-Markovian measures exhibit a rapid increase when the QE is positioned near the PNS, causing a reduction in the QSL, making it shorter than the system’s evolution time. Larger-radius nanospheres sustain non-Markovian dynamics over longer distances, and CSNSs with larger core radii exhibit non-Markovian behavior over extended distances. In addition to the geometrical parameters, the material of the plasmonic subsystem has a crucial influence on the dynamics. So both Gold and Silver shells induce significant Non-Markovian dynamics.