Local absorption spectra of artificial atoms and molecules

We investigate theoretically the spatial dependence of the linear absorption spectra of single and coupled semiconductor quantum dots, where the strong three-dimensional quantum confinement leads to an overall enhancement of Coulomb interaction and, in turn, to a pronounced renormalization of the excitonic properties. We show that---because of such Coulomb correlations and the spatial interference of the exciton wave functions---unexpected spectral features appear whose intensity depends on spatial resolution in a highly nonmonotonic way when the spatial resolution is comparable with the excitonic Bohr radius. We finally discuss how the optical near-field properties of double quantum dots are affected by their coupling.