Quantum-classical correspondence in circularly polarized high harmonic generation

TL;DR

This paper demonstrates that high harmonic generation with circularly polarized lasers can be used to explore quantum-classical correspondence, revealing specific spectral features linked to classical orbits in strong field physics.

Contribution

It introduces a numerical approach showing how HHG spectra with circular polarization reflect underlying classical recollision dynamics and quantum states.

Findings

Narrow harmonic radiation strip observed in spectra.

Presence of a gap of missing harmonics in the lower spectrum.

HHG emission tends to lock to circular polarization in certain spectral regions.

Abstract

Using numerical simulations, we show that atomic high order harmonic generation, HHG, with a circularly polarized laser field offers an ideal framework for quantum-classical correspondence in strong field physics. With an appropriate initialization of the system, corresponding to a superposition of ground and excited state(s), simulated HHG spectra display a narrow strip of strong harmonic radiation preceded by a gap of missing harmonics in the lower part of the spectrum. In specific regions of the spectra, HHG tends to lock to circularly polarized harmonic emission. All these properties are shown to be closely related to a set of key classical periodic orbits that organize the recollision dynamics in an intense, circularly polarized field.