Local optical absorption by confined excitons in single and coupled quantum dots

We investigate optical near-field spectra of single and coupled semiconductor quantum dots. An enhanced role for the Coulomb correlations is predicted, and it is shown that the spectra depend crucially on the spatial resolution of the local probe. The intensity of certain optical peaks as a function of the resolution exhibits an unexpected non-monotonic behavior, which is identified as a fingerprint of Coulomb interactions in zero-dimensional nanostructures.