Scattering of a twisted electron wavepacket by a finite laser pulse

TL;DR

This paper investigates how a twisted electron wavepacket interacts with a finite laser pulse, revealing quantum distortions in its structure and angular momentum that persist after the interaction.

Contribution

It introduces a realistic finite-size model for the electron and laser pulse, and analyzes the resulting quantum dynamics and distortions of the wavepacket.

Findings

Wavepacket motion can be approximated by classical trajectories.

Quantum effects distort the wavepacket's ring structure.

Angular momentum uncertainties increase after interaction.

Abstract

The behavior of a twisted electron colliding with a linearly polarized laser pulse is investigated within relativistic quantum mechanics. In order to better fit the real experimental conditions, we introduce a Gaussian spatial profile for the initial electron state as well as an envelope function for the laser pulse, so the both interacting objects have a finite size along the laser propagation direction. For this setup we analyze the dynamics of various observable quantities regarding the electron state: the probability density, angular momentum, and mean values of the spatial coordinates. It is shown that the motion of a twisted wavepacket can be accurately described by averaging over classical trajectories with various directions of the transverse momentum component. On the other hand, full quantum simulations demonstrate that the ring structure of the wavepacket in the transverse plane can be significantly distorted leading to large uncertainties in the total angular momentum of the electron. This effect remains after the interaction once the laser pulse has a nonzero electric-field area.