Electron matter waves with internal torque

Abstract Investigating or controlling angular momentum in atoms or subatomic structures requires torque on femtosecond and picometre scales, far below the capabilities of laser light. Here we report electron beams with an ultrafast internal torque. We first intersect the electron beam with chiral laser light to create discrete energy sidebands by multiple helical photon absorptions, leading to a correlation between orbital angular momentum and kinetic energy. Then, we use the dispersion of these partial waves due to the electron’s rest mass to convert each electron into a wavefunction with internal torque. The local chirality within an electron matter wave changes from left-handed into achiral towards right-handed within femtosecond times. Such electron matter waves might facilitate research on angular momentum and chirality on atomic and subatomic scales.