A Strongly Perturbed Quantum System: H-Atom in Intense Laser Field

The hydrogen atom provides one of the simplest real systems in nature which can be used to investigate the non-perturbative quantum dynamics in intense laser fields over a great range of the perturbation strengths. Such studies are useful in developing our intuitions about the behaviour of quantum systems in domains where the conventional ideas developed primarily from our knowledge of weak perturbations can no longer be used reliably. In the domain of strong perturbations new phenomena arise which are not observed otherwise.Recently significant progress has been made both experimentally and theoretically in this respect by studying the response of atoms in intense lasers. Prominent among the new effects observed are the so-called above threshold ionization or (ATI)1, above threshold detachment (ATD)2–4, and high harmonic generation5,6.