Microwave cavity searches for low-frequency axion dark matter

TL;DR

This paper proposes a superconducting cavity experiment using oscillating magnetic fields to improve low-frequency axion dark matter detection sensitivity, overcoming geometric suppression present in static field methods.

Contribution

It introduces a novel experimental approach employing GHz superconducting cavities with oscillating fields to enhance axion detection capabilities.

Findings

Potential to surpass static field methods in certain regimes

Analysis of cavity geometries to optimize signal power

Consideration of background noise impacts

Abstract

For low-mass (frequency $\ll$ GHz) axions, dark matter detection experiments searching for an axion-photon-photon coupling generally have suppressed sensitivity, if they use a static background magnetic field. This geometric suppression can be alleviated by using a high-frequency oscillating background field. Here, we present a high-level sketch of such an experiment, using superconducting cavities at $\sim$ GHz frequencies. We discuss the physical limits on signal power arising from cavity properties, and point out cavity geometries that could circumvent some of these limitations. We also consider how backgrounds, including vibrational noise and drive signal leakage, might impact sensitivity. While practical microwave field strengths are significantly below attainable static magnetic fields, the lack of geometric suppression, and higher quality factors, may allow superconducting cavity experiments to be competitive in some regimes.