Axion electrodynamics without Witten effect in metamaterials

Abstract

Artificial media provide a unique playground to test fundamental theories, allowing one to probe the laws of electromagnetism in the presence of hypothetical axions. While some materials are known to realize this physics, here we propose the nonlocal extension of axion electrodynamics. Compared to the usual axion case, the suggested metamaterial features similar optical properties including Kerr and Faraday rotation. However, the external sources in this structure do not induce dyon charges, eliminating the well-celebrated Witten effect. We put forward the design of such a nonreciprocal nonlocal metamaterial and discuss its potential applications.