Ultrafast build-up of polarization in mesoscopic rings

Subjecting a non-interacting mesoscopic ring (MR) to a linearly polarized half-cycle electromagnetic pulse results in a non-uniform, non-equilibrium coherent population of electronic states. A post-pulse charge polarization of the ring is then created within few picoseconds and sustains for times determined by the relaxation time scale. These conclusions are the results of a theoretical analysis of the electronic quantum dynamics of a MR subjected to unipolar pulses. Methods to trace experimentally the charge polarization build-up are suggested.