Induced Quantized Spin Current in Vacuum

TL;DR

This paper predicts a fundamental quantum electrodynamics effect where an external electromagnetic field induces a spin-polarized vacuum, resulting in a measurable vacuum spin current, with an experimental proposal involving liquid crystals.

Contribution

It introduces the concept of a vacuum spin current induced by an electromagnetic field and proposes an experimental method to detect it.

Findings

Vacuum becomes spin polarized under EM field

Prediction of a measurable vacuum spin current

Proposal for detecting spin torque via liquid crystal twist

Abstract

We uncover a fundamental effect of the QED vacuum in an external electromagnetic (EM) field. We show that the quantized vacuum of electrons is spin polarized by the EM field and manifests as a vacuum spin current. An experiment is proposed to measure the spin torque exerted by the spin current by measuring the twisted angle of the director axis of a nematic liquid crystal.