An ultrashort half-cycle pulse (HCP) is a fast (<1 ps) unipolar pulse, followed by a much longer ( 100 ps) and weaker unipolar pulse of opposite polarity. We show that such pulses can be utilized to localize, within femtoseconds, and control, for picoseconds, the electronic motion in a Al_xGa_1–xAs based symmetric double quantum well. The results are obtained by (i) deriving analytically for a model system the type of HCPs that lead to a fast and sustainable localization of a desirable final electron state and (ii) by solving numerically exactly the time-dependent Schrödinger equation for the quantum-well structure in the presence of the HCPs