Double Resonance Strategy for Interferometric Detection of Axions

TL;DR

This work addresses the challenge of detecting axion dark matter in the tens-of-gigahertz mass range by introducing a double-resonant interferometric detector. The approach uses a microwave resonator to transduce the axion-induced field into a resonantly enhanced electric field, which is then read out as an optical phase shift via a high-finesse Fabry–Pérot cavity with multiple passes through an electro-optic medium. The two-stage transduction enables substantial coherent amplification while maintaining tunability across axion masses, with explicit SNR scaling tied to the axion coherence time. Sensitivity estimates suggest reach into the KSVZ and DFSZ QCD axion bands under realistic magnetic fields, laser powers, and integration times, highlighting a complementary optical-path route to existing power-based searches and outlining practical engineering challenges for realization.

Abstract

We propose a double-resonant interferometric strategy for axion dark matter detection that combines microwave circuit resonance with Fabry--Pérot optical enhancement. In a strong magnetic field, axion--photon mixing induces a weak oscillating electric field, which is first amplified by a resonant circuit and then transduced into an optical phase shift via the electro-optic effect. Multiple coherent optical passes through the electro-optic medium accumulate this phase shift, enabling interferometric readout using mature optical techniques. We present the basic operating principle, discuss material requirements, and estimate the achievable sensitivity. For representative parameters, the projected reach extends into the parameter space of well-motivated QCD axion models.

Figures (1)

• Figure 1: Projected sensitivity of experiment with $\text{SNR}=1$ and a $10 \text{ T}$ magnet, $10 \text{ W}$ laser, and integration times of (a) $100\sec$ (b) $1\sec$.