UPconversion Loop Oscillator Axion Detection experiment: A precision frequency interferometric axion dark matter search with a Cylindrical Microwave Cavity

TL;DR

This paper presents a novel room-temperature interferometric axion detection method using a cylindrical microwave cavity, achieving competitive exclusion limits for low-mass axions by upconverting axion-photon interactions into microwave signals.

Contribution

The work introduces a phase-sensitive, dual-mode microwave cavity technique for axion detection, enabling sensitivity to low-mass axions below 1 μeV with potential for improved limits at cryogenic temperatures.

Findings

Excluded axion couplings between 7.44 - 19.38 neV and 74.4 - 74.5 μeV.

Achieved exclusion limits after 2.5 hours measurement.

Proposed cryogenic implementation could enhance sensitivity.

Abstract

First experimental results from a room-temperature table-top phase-sensitive axion haloscope experiment are presented. The technique exploits the axion-photon coupling between two photonic resonator-oscillators excited in a single cavity, allowing low-mass axions to be upconverted to microwave frequencies, acting as a source of frequency modulation on the microwave carriers. This new pathway to axion detection has certain advantages over the traditional haloscope method, particularly in targeting axions below 1 $\mu$eV (240 MHz) in energy where high volume magnets are necessary. At the heart of the dual-mode oscillator, a tunable cylindrical microwave cavity supports a pair of orthogonally polarized modes ($\text{TM}_{\text{0,2,0}}$ and $\text{TE}_{\text{0,1,1}}$), which, in general, enables simultaneous sensitivity to axions with masses corresponding to the sum and difference of the microwave frequencies. The results place axion exclusion limits between 7.44 - 19.38 neV, excluding a minimal coupling strength above $3\times 10^{-3}$ 1/GeV, and between 74.4 - 74.5 $\mu$eV, excluding a minimal coupling strength above $10^{-2}$ 1/GeV, after a measurement period of two and a half hours. We show that a state-of-the-art frequency-stabilized cryogenic implementation of this technique may achieve competitive limits in a large range of axion-space.