  We study the efficiency of modulated laser pulses to produce efficient and
fast charge localization transitions in a two-electron double quantum dot. We
use a configuration interaction method to calculate the electronic structure of
a quantum dot model within the effective mass approximation. The interaction
with the electric field of the laser is considered within the dipole
approximation and optimal control theory is applied to design high-fidelity
ultrafast pulses in pristine samples. We assessed the influence of the presence
of Coulomb charged impurities on the efficiency and speed of the pulses. A
protocol based on a two-step optimization is proposed for preserving both
advantages of the original pulse. The processes affecting the charge
localization is explained from the dipole transitions of the lowest lying
two-electron states, as described by a discrete model with an effective
electron-electron interaction.
