Ultrafast control of electronic motion in semiconductor nano and mesoscopic structures

摘要

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-x)Ak_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 oscillates in the ring as long as the coherence is preserved and decays on a time scale determined by the relaxation time.