Extended coherent exciton states in quantum dot arrays

Resonant energy transfer is a mechanism for excitation exchange in quantum dot arrays. We explore this process by calculating the coupling strength, and by studying the detailed dynamics of extended coherent exciton states created in an array of quantum dots. Estimates of the Forster coupling V-F are obtained from a microscopic description of the exciton levels in the quantum dot. We present results for different materials (CdS, CdSe, GaAs, and InP) as function of dot features. V-F shows a nonmonotonic variation with a maximum value that depends on the specific dot sizes, material parameters, and dot separation. Analysis of coupled quantum dots using the time evolution of the density matrix when the Forster channel is open shows that a coherent coupling appears in different regimes. Realistic parameters, used throughout the study of the dynamics, suggest the practical realization of these phenomena in actual systems.