  We optically probe the spectrum of ground and excited state transitions of an
individual, electrically tunable self-assembled quantum dot molecule.
Photocurrent absorption measurements show that the spatially direct neutral
exciton transitions in the upper and lower dots are energetically separated by
only ~2 meV. Excited state transitions ~8-16 meV to higher energy exhibit
pronounced anticrossings as the electric field is tuned due to the formation of
hybridized electron states. We show that the observed excited state transitions
occur between these hybridized electronic states and different hole states in
the upper dot. By simultaneously pumping two different excited states with two
laser fields we demonstrate a strong (88% on-off contrast) laser induced
switching of the optical response. The results represent an electrically
tunable, discrete coupled quantum system with a conditional optical response.
