Electronic coupling of vertically coupled quantum dots: Magnetic and electric field effects

In this work, we consider two vertically coupled Ga0.68In0.32As quantum dots embedded in GaAs. The influence of the Jots with different sizes on the energy levels is analyzed, as well as magnetic and electric field effects. We use a square-well potential to model the confinement of electrons in the self-assembled quantum dots. Including the long-range Coulomb interaction, we calculate the spin exchange energy using the Hund-Milliken technique. We determine the magnetization, including the Zeeman splitting which causes a singlet-triplet crossing. The crossing can be reversed by applying an in-plane electric field. The application of an in-plane electric field facilitates the tuning of spin energies and wave-functions. As an especially interesting situation, switching of the spin coupling arises between dots of different sizes and separations. This switching is important for logic gates in quantum computation.