Hannover 2003 – wissenschaftliches Programm

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A: Atomphysik

A 11: Postersitzung 1

A 11.35: Poster

Dienstag, 25. März 2003, 16:00–18:30, Poster

Controlling quantum coherence with ultrashort half-cycle laser pulses — •Alex Matos-Abiague and Jamal Berakdar — Max-Planck Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle

We investigate the quantum coherence and the coherent suppression of tunneling of an electron driven by a train of unidirectional ultrashort half-cycle laser pulses in a double quantum well. For Gaussian-like shape pulses the time-dependent Schrödinger equation is numerically solved. It is shown that there exist ranges of parameters in which although the use of cw laser fields can not suppress the tunnelling, dynamical localization can be induced by employing a train of unidirectional ultrashort half-cycle pulses. When the time-periodic unidirectional half-cycle pulses are applied, an initially trapped electron maintains, in general, its localization. For certain values of the pulse parameters, however, the quantum tunnelling is coherently restored. A simplified analytical model that can reproduce the main features of the numerical calculations is also presented. The analytical model provides simple relations for determining the values of the pulse parameters that optimize the localization and delocalization processes.