Observation of low-lying excitations of electrons in coupled quantum   dots
  Tunneling excitations of electrons in dry-etched modulation-doped AlGaAs/GaAs coupled quantum dots (QDs) are probed by resonant inelastic light scattering. A sequence of intra- and intershell excitations are found at energies determined by the interplay between the QD confinement energy $\hbar \omega_0$ and the tunneling gap $\Delta_{SAS}$, the splitting between the symmetric and anti-symmetric delocalized single particle molecular states. The narrow line-widths displayed by electronic excitations in these nanostructures indicate promising venues for the spectroscopic investigation of entanglement of electron states in these artificial molecules. 
Cesar Pascual Garcia, Sokratis Kalliakos, Vittorio Pellegrini, Aron   Pinczuck, Brian S. Dennis, Loren N. Pfeiffer, Ken W. West