Space-time resolved simulation of femtosecond nonlinear light-matter interactions using a holistic quantum atomic model: Application to near-threshold harmonics

TL;DR

This paper presents a novel, efficient computational method for simulating femtosecond light-matter interactions in gases, capturing quantum effects like high-harmonic generation with significantly reduced computational cost.

Contribution

The authors develop a holistic quantum atomic model using a delta-function potential for full 3D space-time femtosecond pulse simulations, enabling efficient and accurate quantum effect incorporation.

Findings

Successfully simulated near-threshold harmonic generation in Xenon.

Achieved over 100-fold reduction in computation time.

Provided qualitative comparison with experimental EUV generation data.

Abstract

We introduce a new computational approach for femtosecond pulse propagation in the transparency region of gases that permits full resolution in three space dimensions plus time while fully incorporating quantum coherent effects such as high-harmonic generation and strong-field ionization in a holistic fashion. This is achieved by utilizing a one-dimensional model atom with a delta-function potential which allows for a closed-form solution for the nonlinear optical response due to ground-state to continuum transitions. It side-steps evaluation of the wave function, and offers more than one hundred-fold reduction in computation time in comparison to direct solution of the atomic Schr\"odinger equation. To illustrate the capability of our new computational approach, we apply it to the example of near-threshold harmonic generation in Xenon, and we also present a qualitative comparison between our model and results from an in-house experiment on extreme ultraviolet generation in a femtosecond enhancement cavity.