Electromagnetic Duality and the Electric Memory Effect

TL;DR

This paper explores the structure of large gauge transformations in quantum electrodynamics, revealing an ISO(2) algebra that unifies electric and magnetic symmetries and connects to electromagnetic memory effects.

Contribution

It identifies the dual gauge symmetry at null infinity as part of the ISO(2) algebra, linking electric and magnetic aspects of electromagnetic memory.

Findings

Large gauge transformations form an ISO(2) algebra.

Residual gauge symmetry and dual gauge symmetry correspond to the algebra's generators.

Electric Aharonov-Bohm effect measures electromagnetic memory from large gauge transformations.

Abstract

We study large gauge transformations for soft photons in quantum electrodynamics which, together with the helicity operator, form an ISO(2) algebra. We show that the two non-compact generators of the ISO(2) algebra correspond respectively to the residual gauge symmetry and its electromagnetic dual gauge symmetry that emerge at null infinity. The former is helicity universal (electric in nature) while the latter is helicity distinguishing (magnetic in nature). Thus, the conventional large gauge transformation is electric in nature, and is naturally associated with a scalar potential. We suggest that the electric Aharonov-Bohm effect is a direct measure for the electromagnetic memory arising from large gauge transformations.