Intrinsic dipole–dipole excitonic coupling in GaN quantum dots: application to quantum information processing

We propose to use GaN quantum dots as building blocks of a solid state quantum bit. The existence of a strong built in electric field induced by the spontaneous polarization and by the piezoelectricity is exploited to entangle the states in coupled quantum dots without external fields. The electro-optical response of the coupled GaN quantum dots is investigated theoretically by means of a realistic description of Coulomb-correlated few-electron states, obtained via a direct-diagonalization approach. We show that the built-in electric field in nitrides induces intrinsic dipole–dipole coupling of the order of some milli-electron-volt and thus allows the implementation of quantum information processing. As an example we will implement the quantum XOR gate. Quantum operations are achieved by a sequence of femtosecond multicolor laser pulses.