  We use photoluminescence spectroscopy to investigate the ground state of
single self-assembled InGaAs lateral quantum dot molecules. We apply a voltage
along the growth direction that allows us to control the total charge occupancy
of the quantum dot molecule. Using a combination of computational modeling and
experimental analysis, we assign the observed discrete spectral lines to
specific charge distributions. We explain the dynamic processes that lead to
these charge configurations through electrical injection and optical
generation. Our systemic analysis provides evidence of inter-dot tunneling of
electrons as predicted in previous theoretical work.
