Non-perturbative QED Model with Dressed States to Tackle HHG in Ultrashort Intense Laser Pulses

TL;DR

This paper develops a non-perturbative QED model using dressed states to analyze high harmonic generation in ultrashort intense laser pulses, revealing new insights and verifying the presence of weak even-order harmonics.

Contribution

It introduces a generalized dressed state QED model for HHG in multi-mode fields, providing an analytical formula with intuitive interpretation and new perspectives.

Findings

Verification of weak even-order harmonic photons

Analytical formula for HHG in ultrashort pulses

New perspective on HHG mechanisms

Abstract

A generalization of non-perturbative QED model for high harmonic generation is developed for the multi-mode optical field case. By introducing classical-field-dressed quantized Volkov states analytically, a formula to calculate HHG for hydrogen-like atom in ultrashort intense laser pulse is obtained, which has a simple intuitive interpretation. The dressed state QED model indicates a new perspective to understand HHG, for example, the presence of the weak even-order harmonic photons, which has been verified by both theoretical analysis and numerical computation. Long wavelength approximation and strong field approximation are involved in the development of the formalism.