Search for invisible axion dark matter of mass m$_a=43~\mu$eV with the QUAX--$a\gamma$ experiment

TL;DR

The QUAX--aγ experiment searches for galactic axion dark matter around 43 μeV using a cooled high-Q cavity and quantum-limited amplifiers, setting new limits on axion-photon coupling.

Contribution

This work demonstrates a sensitive haloscope setup capable of probing axion-photon coupling at the QCD axion mass scale with quantum-limited amplification.

Findings

Set a new upper limit on axion-photon coupling: g_{aγγ}<0.639×10^{-13} GeV^{-1}

Achieved quantum-limited noise performance with Josephson parametric amplifier

Successfully operated a high-Q cavity haloscope at 43 μeV mass range

Abstract

A haloscope of the QUAX--$a\gamma$ experiment composed of an oxygen-free high thermal conductivity-Cu cavity inside an 8.1 T magnet and cooled to $\sim200$ mK is put in operation for the search of galactic axion with mass $m_a\simeq43~\mu\text{eV}$. The power emitted by the resonant cavity is amplified with a Josephson parametric amplifier whose noise fluctuations are at the standard quantum limit. With the data collected in about 1 h at the cavity frequency $\nu_c=10.40176$ GHz, the experiment reaches the sensitivity necessary for the detection of galactic QCD-axion, setting the $90\%$ confidence level limit to the axion-photon coupling $g_{a\gamma\gamma}<0.639\times10^{-13}$ GeV$^{-1}$.