Axion Detection with Precision Frequency Metrology

TL;DR

This paper proposes a novel axion detection method using precision frequency and phase measurements in cavity resonators, offering a potentially sensitive, tabletop alternative to cryogenic experiments by leveraging mode coupling and phase sensitivity.

Contribution

It introduces a new detection technique based on frequency metrology and mode coupling, expanding axion search methods beyond traditional thermal fluctuation limits.

Findings

Demonstrates linear mode-mode coupling mediated by axions in dual mode cavities.

Calculates axion signal-to-phase spectral density for different detection schemes.

Shows the approach can achieve sensitivity comparable to cryogenic experiments without cryogenic cooling.

Abstract

We investigate a new class of galactic halo axion detection techniques based on precision frequency and phase metrology. Employing equations of axion electrodynamics, it is demonstrated how a dual mode cavity exhibits linear mode-mode coupling mediated by the axion upconversion and axion downconversion processes. The approach demonstrates phase sensitivity with an ability to detect axion phase with respect to externally pumped signals. Axion signal to phase spectral density conversion is calculated for open and closed loop detection schemes. The fundamental limits of the proposed approach come from the precision of frequency and environment control electronics, rather than fundamental thermal fluctuations allowing for table-top experiments approaching state-of-the-art cryogenic axion searches in sensitivity. Practical realisations are considered, including a TE-TM mode pair in a cylindrical cavity resonator and two orthogonally polarised modes in a Fabry-P{\'e}rot cavity.