Electric field control of exciton states in quantum dot molecules

Semiconductor nanostructures have attracted considerable interest during the recent years in view of the potential application in quantum information processing. In particular, quantum dots have been suggested to fulfill an essential requirement for quantum computation: controllable interaction that couples two quantum dot qubits. Previous experiments on two vertically aligned quantum dots have demonstrated the formation of coupled exciton states. We show that this coupling between two In0.60Ga0.40As/GaAs quantum dots can be tuned by an electric field applied along the molecule axis. This controllable coupling in such a relatively simple configuration could be implemented in a solid-state-based quantum device.