Quantum dot-quantum dot interactions mediated by a metal nanoparticle: Towards a fully quantum model

We study the interactions between two semiconductor quantum dots (SQDs) coupled to a metal nanoparticle using different approximations. In particular, we identify and address issues in modeling the system using a semiclassical approach. We find that a semiclassical approach to model the coupling between the SQDs can lead to unstable, oscillatory, and chaotic behavior in a strong SQD-SQD coupling regime. This nonlinear behavior is shown to be due to a breaking of the identical particle symmetry. Additionally, we see that this chaotic behavior is closely related to the type of decoherence present in the system, specifically, whether the decoherence is collective or noncollective between the two SQDs. This provides insight into proper accounting of these important, but often neglected, interactions. When the system is modeled using a more quantum mechanical approach, this chaotic regime is absent. Finally, we compare the two models on a system with a strong plasmon-mediated interaction between the SQDs and a weak direct interaction between them. In this case, we find that while the results of the two models are similar, dipole blockade and the level splitting of the single-exciton states in the quantum model give rise to nontrivial differences between the two models. DOI: 10.1103/PhysRevB.87.125423