The ehrenfest theorem and quantitative predictions of hhg based on the three-step model

Abstract

A primary challenge in high-harmonic generation (HHG) experiments is the optimization of the photon yield. To address this challenge, quantitative theoretical modeling of the single-atom response as well as propagation effects is needed. It has been shown that the three-step model (TSM) [1] gives an excellent qualitative description of the single-atom response to an intense laser pulse [2]. The structure of the spectrum and in particular the cutoff frequency are predicted correctly. However, so far there was only poor agreement between the photon yield predicted by the TSM and by direct numerical solutions of the Schrödinger equation (NSE). In fact, there is a discrepancy of about an order of magnitude in the radiation amplitude, which translates to a two orders of magnitude discrepancy in the photon yield. Moreover, the discrepancy is not constant over the spectrum. In other words, the TSM spectrum is also distorted in its shape. © 2007 Springer-Verlag New York.