Quantum-mechanical model for ultrahigh-order harmonic generation in the moderately relativistic regime - art. no. 011403

A quantum theory of ultrahigh-order harmonic generation is presented that g eneralizes the Lewenstein model into the relativistic regime. Various effec ts appear in the harmonic spectrum: a multiplateau structure in the weakly relativistic case: for stronger fields, the interference pattern familiar f rom the nonrelativistic case disappears, the height of the plateau decrease s towards high harmonic orders, and the cutoff is lower compared to the non relativistic case. All of these features are explained in terms of relativi stic quantum trajectories.