  A novel approach for the control of exciton-exciton Coulomb coupling in
semiconductor macroatoms/molecules is proposed. We show that by applying
properly tailored external fields, we can induce ---or significantly
reinforce--- excitonic dipoles, which in turn allows to control and magnify
intra- as well as inter-dot few-exciton effects. Such dipole-dipole interaction
mechanism will be accounted for within a simple analytical model, which is
found to be in good agreement with fully three-dimensional calculations. The
proposed approach may play an important role for the design and realization of
fully-optical quantum gates as well as ultrafast optical switches.
