GaN quantum dot based quantum information/computation processing

In this paper we propose to use GaN quantum dots (QDs) as building blocks for solid state quantum computing devices. The existence of a strong built-in electric field induced by the spontaneous polarization and by the piezoelectricity is exploited to entangle few-exciton states in coupled QDs without the use of external fields. The analysis of the electro-optical response of the coupled GaN QDs is based on a realistic-i.e. fully tri-dimensional-description of Coulomb-correlated few-electron states, obtained via a direct-diagonalization approach. The combined effect of the built-in electric field and ultrafast sequences of multicolor laser pulses in the few-carrier regime is investigated. We show how the built-in field induces intrinsic dipole-dipole coupling and thus allows the implementation of quantum information processing. As an example we will implement basic quantum information gates and we will demonstrate that our implementation scheme is compatible with a subpicosecond operation timescale, i.e. with timescales much lower than the decoherence time of the system. (C) 2002 Elsevier Science Ltd. All rights reserved.