Eur. Phys. J. B (2017) 90: 91
https://doi.org/10.1140/epjb/e2017-70741-4

Regular Article

Optimization of the ionization time of an atom with tailored laser pulses: a theoretical study

¹ Institut Lumière Matière, UMR 5306 Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne Cedex, France
² ARAID Foundation, Edificio CEEI, María Luna 1, 50018 Zaragoza, Spain
³ Institute for Biocomputation and Physics of Complex Systems of the University of Zaragoza, Mariano Esquillor s/n, 50018 Zaragoza, Spain
⁴ Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06099 Halle, Germany

^a e-mail: acastro@bifi.es

Received: 20 December 2016
Published online: 17 May 2017

Abstract

How fast can a laser pulse ionize an atom? We address this question by considering pulses that carry a fixed time-integrated energy per-area, and finding those that achieve the double requirement of maximizing the ionization that they induce, while having the shortest duration. We formulate this double-objective quantum optimal control problem by making use of the Pareto approach to multi-objective optimization, and the differential evolution genetic algorithm. The goal is to find out how a precise time-profiling of ultra-fast, large-bandwidth pulses may speed up the ionization process. We work on a simple one-dimensional model of hydrogen-like atoms (the Pöschl-Teller potential) that allows to tune the number of bound states that play a role in the ionization dynamics. We show how the detailed shape of the pulse accelerates the ionization, and how the presence or absence of bound states influences the velocity of the process.