Coulomb-corrected strong-field quantum trajectories beyond dipole approximation

TL;DR

This paper extends the Coulomb-corrected strong-field approximation beyond the dipole approximation to accurately predict non-dipole effects in photoelectron spectra, revealing counterintuitive momentum shifts due to interplay of Lorentz and Coulomb forces.

Contribution

It introduces a semi-analytical method that treats magnetic and Coulomb forces perturbatively, accurately capturing non-dipole effects in strong-field ionization beyond the dipole approximation.

Findings

Reproduces full numerical solutions of electron dynamics.

Predicts momentum shifts against laser propagation direction.

Highlights interplay of Lorentz and Coulomb forces in electron trajectories.

Abstract

Non-dipole effects in strong-field photoelectron momentum spectra have been revealed experimentally [C.T.L. Smeenk et al., Phys. Rev. Lett. 106, 193002 (2011); A. Ludwig et al., Phys. Rev. Lett. 113, 243001 (2014)]. For certain laser parameters and photoelectron momenta the spectra were found to be shifted against the laser propagation direction whereas one would naively assume that the radiation pressure due to the $\vec{v}\times\vec{B}$-force pushes electrons always in propagation direction. Only the interplay between Lorentz and Coulomb force may give rise to such counterintuitive dynamics. In this work, we calculate the momentum-dependent shift in and against the propagation direction by extending the quantum trajectory-based Coulomb-corrected strong-field approximation beyond the dipole approximation. A semi-analytical treatment where both magnetic and Coulomb force are treated perturbatively but simultaneously reproduces the results from the full numerical solution of the equations of motion.