Strong-field photoionization by circularly polarized light

TL;DR

This paper shows that strong-field ionization with circularly polarized light can be understood as an adiabatic process in a rotating frame, revealing a conservation law for the electron's energy in rotationally invariant potentials.

Contribution

It introduces a classical-quantum correspondence that uncovers a new conservation law in strong-field ionization beyond the standard approximation.

Findings

Energy conservation in the rotating frame for tunneling electrons

Adiabatic behavior of ionization under circular polarization

Classical-quantum correspondence confirms the conservation law

Abstract

We demonstrate that strong-field ionization of atoms driven by circularly polarized light becomes an adiabatic process when described in the frame rotating with the laser field. As a direct consequence, a conservation law emerges: in the rotating frame the energy of the tunneling electron is conserved for rotationally invariant potentials. This conservation law, arising from a classical picture, is retrieved through a proper classical-quantum correspondence when considering the full quantum system, beyond the Strong Field Approximation.