Optically Probing Spin and Charge Interactions in an Tunable Artificial   Molecule
  We optically probe and electrically control a single artificial molecule containing a well defined number of electrons. Charge and spin dependent inter-dot quantum couplings are probed optically by adding a single electron-hole pair and detecting the emission from negatively charged exciton states. Coulomb and Pauli blockade effects are directly observed and hybridization and electrostatic charging energies are independently measured. The inter-dot quantum coupling is confirmed to be mediated predominantly by electron tunneling. Our results are in excellent accord with calculations that provide a complete picture of negative excitons and few electron states in quantum dot molecules. 
H. J. Krenner, E. C. Clark, T. Nakaoka, M. Bichler, C. Scheurer, G.   Abstreiter, J. J. Finley