Photon Angular Momentum and Zero-Point Oscillations

TL;DR

This paper explores how zero-point oscillations in quantum dipole sources contribute to the angular momentum of single-photon radiation, revealing phenomena unexplained by classical electrodynamics.

Contribution

It demonstrates that zero-point oscillations are responsible for the angular momentum in photon radiation from a dipole, providing a quantum explanation for a classical anomaly.

Findings

Zero-point oscillations account for photon angular momentum.

Classical electrodynamics cannot explain this angular momentum.

Quantum effects are essential for understanding radiation from localized sources.

Abstract

Radiation from a localized, oscillating charge distribution can have angular momentum that cannot be explained in classical electrodynamics. We consider the simplest example -- electric dipole radiation of a single photon -- and show that this angular momentum is attributable to zero-point oscillations in unexcited states of the dipole source.