Matos Abiague, A. S., Berakdar, J.

We study the charge dynamics in a double quantum well and in ballistic mesoscopic rings driven by half-cycle pulses. It is shown that such pulses can be utilized to localize, within femtoseconds, and control, for picoseconds, the electronic motion in a Ga_1-xAl_xAs based double quantum well. To identify the pulse parameters that appropriate for an efficient control process we developed a simplified analytical model and corroborated the results by performing full numerical calculations. We also show that when a thin ballistic mesoscopic ring is subjected to a linearly polarized HCP a post-pulse (and therefore field-free) polarization is induced in the ring. The non-equilibrium post-pulse polarization oscillated in the ring as long as the coherence is preserved and decays on a time scale determined by the relaxation time.

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