Local dynamics in high-order-harmonic generation using Bohmian trajectories

Abstract

We investigate high-order-harmonic generation from a Bohmian-mechanical perspective and find that the innermost part of the core, represented by a single Bohmian trajectory, leads to the main contributions to the high-harmonic spectra. Using time-frequency analysis, we associate this central Bohmian trajectory to an ensemble of unbound classical trajectories leaving and returning to the core, in agreement with the three-step model. In the Bohmian scenario, this physical picture builds up nonlocally near the core via the quantum mechanical phase of the wave function. This implies that the flow of the wave function far from the core alters the central Bohmian trajectory. We also show how this phase degrades in time for the peripheral Bohmian trajectories as they leave the core region.