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Controllable interactions that couple quantum dots are a key requirement in the search for scalable solid state implementations for quantum information technology. From optical studies of excitons and corresponding calculations, we demonstrate that an electric field on vertically coupled pairs of In(0.6)Ga(0.4)As/GaAs quantum dots controls the mixing of the exciton states on the two dots and also provides controllable coupling between carriers in the dots.

Self-organized InAs quantum dashes grown on In0.53Ga0.23Al0.24As∕InP have been investigated by chemically sensitive scanning transmission electron microscopy. The quantum dashes, which consist of pure InAs, exhibit a triangular cross section. Most important, the quantum dash size depends linearly on the nominal InAs layer thickness and can be varied by a factor of 3 without changing the height∕width ratio. Thus, the emission wavelength can be controlled between 1.37 and 1.9μm without modifying shape and composition of the quantum dashes by adjusting a single growth parameter.

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