Electromagnetic duality anomaly in accelerating waveguides

TL;DR

This paper demonstrates that quantum effects in accelerating waveguides break classical electromagnetic duality symmetry, leading to spontaneous photon pair creation and helicity imbalance, which could be experimentally observed.

Contribution

It reveals a quantum duality anomaly in accelerating waveguides, showing vacuum excitation and helicity imbalance due to acceleration-induced symmetry breaking.

Findings

Photon pairs are spontaneously generated from the vacuum.

Helicity imbalance occurs due to acceleration.

Classical duality symmetry is broken quantum mechanically.

Abstract

The classical symmetry of the source-free Maxwell equations under electric-magnetic duality rotations leads to a conserved Noether charge, corresponding to the circular polarization of light. We show that, in quantum field theory, the vacuum expectation value of this charge is no longer time-independent inside a long, cylindrical waveguide undergoing both linear and rotational acceleration from rest. Specifically, photon pairs are spontaneously excited from the quantum vacuum by the accelerated background, while the helical motion induces an imbalance in the number of right- and left-handed modes produced. This photon helicity non-conservation reflects a genuine quantum effect that breaks the classical duality symmetry. The model considered paves the way for experimental studies.