We have studied the excitonic absorption of single In(Ga)As self-assembled
quantum dots by photoluminenscence excitation spectroscopy. We find that th
e absorption spectrum varies drastically with the symmetry of the dot struc
tures: the lower the symmetry is, the more complicated is the structure of
the excitonic absorption. For dots of high symmetry we demonstrate that the
mixing of quantum configurations by two-body interactions in the electron-
hole complex leads to distinct absorption spectra controlled by the number
of confined electronic shells.