Resonance fluorescence spectrum of a p-doped quantum dot coupled to a metallic nanoparticle

Abstract

The resonance fluorescence spectrum (RFS) of a hybrid system consisting of a p-doped semiconductor quantum dot (QD) coupled to a metallic nanoparticle (MNP) is analyzed. The quantum dot is described as a four-level atomlike system using the density matrix formalism. The lower levels are Zeeman-split hole spin states and the upper levels correspond to positively charged excitons containing a spin-up, spin-down hole pair and a spin electron. A linearly polarized laser field drives two of the optical transitions of the QD and produces localized surface plasmons in the nanoparticle, which act back upon the QD. The frequencies of these localized plasmons are very different along the two principal axes of the nanoparticle, thus producing an anisotropic modification of the spontaneous emission rates of the allowed optical transitions, which is accompanied by very minor local field corrections. This manifests into dramatic modifications in the RFS of the hybrid system in contrast to the one obtained for the isolated QD. The RFS is analyzed as a function of the nanoparticle's aspect ratio, the external magnetic field applied in the Voigt geometry, and the Rabi frequency of the driving field. It is shown that the spin of the QD is imprinted onto certain sidebands of the RFS, and that the signal at these sidebands can be optimized by engineering the shape of the MNP.