Searching for Ultra-Light Axions with Twisted Cavity Resonators of Anyon Rotational Symmetry with Bulk Modes of Non-Zero Helicity

Zoom link - see email to CDM member from ciaran.ohare@sydney.edu.au

Abstract
Möbius-ring resonators stem from a well-studied and fascinating geometrical structure which features a one-sided topology; the Möbius strip, and have been shown to exhibit fermion rotational symmetry with respect to a ring resonator with no twist (which exhibits boson rotational symmetry) [1]. A new type of electromagnetic resonator is discussed, appearing as twisted hollow structures using equilateral triangular cross-sections, leading to the realisation of a cavity with anyon rotational symmetry. Unlike all previous cavity resonators, the anyon resonator permits the existence of bulk resonant modes that exhibit non-zero electromagnetic helicity in vacuo, with non zero overlap of the electric and magnetic mode eigenvectors, integrated over the cavity volume. In the up-conversion limit, we show that these non-zero helical modes couple naturally to ultralight dark matter axions within the bandwidth of the resonator by adding amplitude modulated sidebands through the axion-photon chiral anomaly. Thus, we show a sensitive ultra-light dark matter experiment may be realised by implementing such a resonator in an ultra-stable oscillator configuration and searching for signals in the Fourier spectrum of amplitude fluctuations. This removes the typical requirement for an external magnetic field and therefore permits the use of superconducting materials to reduce surface losses and enhance sensitivity to axions.