# Controlling electron spin dynamics in bichromatic Kapitza-Dirac scattering by the laser field polarization

## TL;DR

This paper investigates how the polarization of bichromatic laser fields influences electron spin dynamics during Kapitza-Dirac scattering, revealing conditions for spin control and filtering.

## Contribution

It provides analytical and numerical analysis of spin-dependent scattering probabilities under various laser polarization geometries, highlighting new spin manipulation techniques.

## Key findings

- Spin dynamics are suppressed at low intensities with circular polarization.
- Strong spin effects occur at low intensities with mixed polarization modes.
- A polarization configuration acts as a spin filter for electrons.

## Abstract

Spin-dependent Kapitza-Dirac scattering of electron beams from counterpropagating bichromatic laser waves in various polarization geometries is studied. The corresponding scattering probabilities are obtained by analytical and numerical solutions of the time-dependent Dirac equation, assuming a field frequency ratio of 2. When the fundamental field mode is circular-polarized, we show that spin dynamics are generally suppressed at low intensities, but can become distinct at high intensities. Conversely, when a linearly or elliptically polarized fundamental mode is combined with a second harmonic of circular polarization, strong spin effects arise already at low field intensities. In particular, a polarization configuration is identified which acts as a spin filter for free electrons.