# Spin polarization of electrons by ultraintense lasers

## TL;DR

This paper demonstrates that ultraintense laser interactions can rapidly induce high degrees of electron spin polarization through the Sokolov-Ternov effect, occurring in less than 10 femtoseconds at intensities above 10^{23} W/cm^2.

## Contribution

It introduces the possibility of achieving ultrafast electron spin polarization using high-intensity lasers, extending the understanding of spin dynamics in extreme fields.

## Key findings

- Spin polarization can reach 70%-90% in less than 10 fs.
- High intensity lasers can induce rapid spin flip transitions.
- The Sokolov-Ternov effect is effective in laser-matter interactions at extreme intensities.

## Abstract

In a strong magnetic field, ultra-relativistic electrons or positrons undergo spin flip transitions as they radiate, preferentially spin polarizing in one direction -- the Sokolov-Ternov effect. Here we show that this effect could occur very rapidly (in less than 10 fs) in high intensity ($I\gtrsim10^{23}$ W/cm$^{2}$) laser-matter interactions, resulting in a high degree of electron spin polarization (70%-90%).