  Detailed theoretical studies of the electronic structure of
(InGa)(AsSb)/GaAs/GaP quantum dots are presented. This system is unique since
it exhibits concurrently direct and indirect transitions both in real and
momentum space and is attractive for applications in quantum information
technology, showing advantages as compared to the widely studied (In,Ga)As/GaAs
dots. We proceed from the inspection of the confinement potentials for ${\bf
k}\neq 0$ and ${\bf k}= 0$ conduction and ${\bf k}= 0$ valence bands, through
the formulation of ${\bf k}\cdot{\bf p}$ calculations for ${\bf k}$-indirect
transitions, up to the excitonic structure of $\Gamma$-transitions. Throughout
this process we compare the results obtained for dots on both GaP and GaAs
substrates enabling us to make a direct comparison to the (In,Ga)As/GaAs
quantum dot system. We also discuss the realization of quantum gates.
