Disorder around an atom makes quantum electrons behave classically

When a hydrogen-like atom sits inside a disordered, scattering environment and is hit with an intense laser, the photoelectron gradually loses its quantum coherence and starts hugging specific classical trajectories — unstable periodic orbits. This is quantum scarring, a phenomenon usually spotted in static billiard-like systems, but here it emerges live in the real-time wavepacket dynamics. The result links open-system decoherence to a striking quantum-to-classical crossover that leaves a clear fingerprint in high-harmonic emission spectra.