  We investigate theoretically the slowdown of optical pulses due to
quantum-coherence effects in InGaAs-based quantum dots and quantum dot
molecules. Simple models for the electronic structure of quantum dots and, in
particular, quantum-dot molecules are described and calibrated using numerical
simulations. It is shown how these models can be used to design optimized
quantum-dot molecules for quantum coherence applications. The wave functions
and energies obtained from the optimizations are used as input for a
microscopic calculation of the quantum-dot material dynamics including carrier
scattering and polarization dephasing. The achievable group velocity slowdown
in quantum-coherence V schemes consisting of quantum-dot molecule states is
shown to be substantially higher than what is achievable from similar
transitions in typical InGaAs-based single quantum dots.
