Atomic ‘Scars’ Reveal How Quantum Systems Become Classical

Simon His and colleagues at the Sorbonne University have demonstrated how disorder fundamentally alters the behaviour of electrons ejected from atoms during high-order harmonic generation. Their one-dimensional simulations reveal that scattering from a disordered environment causes a shift from quantum to classical behaviour in photoelectron dynamics, evidenced by the localisation of probability density around unstable periodic orbits. This process, mirroring the phenomenon of quantum scars, uniquely occurs within a time-dependent framework, directly observable in real-time dynamics and offering new insights into strong-field physics. Simulations demonstrate a transition from quantum to classical behaviour in photoelectrons, with harmonic peak intensities reducing by…