High-order harmonic generation from an atom in a disordered environment

TL;DR

This paper uses 1D simulations to explore how disordered environments affect high-order harmonic generation in atoms, revealing a transition from quantum to classical behavior due to decoherence.

Contribution

It introduces a novel analysis of high-order harmonic generation in atoms within disordered environments using open quantum system models.

Findings

Local dephasing causes global decoherence of the photoelectron wavepacket.

Decoherence leads to localization around classical unstable periodic orbits.

Quantum scars emerge dynamically in the time-dependent photoelectron dynamics.

Abstract

Using one-dimensional simulations analyzed through the lens of open quantum systems, we study the photoelectron's strong-field dynamics from an atom surrounded by a scattering environment stochastically structured. We theoretically investigate high-order harmonic generation from this situation. We show that local dephasing of the photoelectron wavepacket induced by elastic scattering leads to global decoherence. This drives a transition from quantum to classical behavior, as witnessed by the photoelectron probability density localizing around specific trajectories of the classical analog system: unstable periodic orbits. This phenomenon mirrors quantum scars traditionally observed in the eigenfunctions of time-independent systems, such as quantum billiards. Here, it emerges in-situ within a time-dependent framework, manifesting directly in the real-time dynamics from the ground state rather than solely through spectral analysis.