Optimal control of attosecond pulse synthesis from high-order harmonic generation

Numerical solutions of the time-dependent Schrödinger equation for a three-dimensional H atom and an efficient genetic algorithm are used to optimize short intense excitation laser pulses in order to generate high-order harmonics from which we synthesize single attosecond pulses. It is shown that chirping of excitation pulses at intensities $\sim {10}^{14}\mathrm{W}∕{\text{cm}}^2$ and duration of up to $\sim 16\text{fs}$ can lead to synthesis of single attosecond pulses. The optimal excitation pulses and the phases of the generated harmonics are compared with the nonoptimized ones, showing thus the usefulness of genetic algorithm schemes in the search of optimal conditions for synthesizing single attosecond pulses.