Heterodyne broadband detection of axion dark matter

Asher Berlin,Kevin Zhou,Raffaele Tito D’Agnolo,Sebastian A R Ellis

doi:10.1103/physrevd.104.l111701

Abstract

We propose a new broadband search strategy for ultralight axion dark matter that interacts with electromagnetism. An oscillating axion field induces transitions between two quasi-degenerate resonant modes of a superconducting cavity. In two broadband runs optimized for high and low masses, this setup can probe unexplored parameter space for axion-like particles covering fifteen orders of magnitude in mass, including astrophysically long-ranged fuzzy dark matter.

Highlights

Evidence for dark matter (DM) has been accumulating for almost 90 years [1] and its microscopic nature remains one of the most important open questions in physics
We have proposed a heterodyne approach to search for ultralight axion dark matter through its coupling to electromagnetism, which applies recent developments in the manufacturing and control of SRF cavities
Our setup is sensitive to much lighter axions, including the entire allowed mass range for fuzzy dark matter, ma ≥ Oð10−21Þ eV [69,70,71,72,73,74], thereby complementing ultralight axion searches that use nonelectromagnetic couplings [75,76,77,78]

Summary

INTRODUCTION

Evidence for dark matter (DM) has been accumulating for almost 90 years [1] and its microscopic nature remains one of the most important open questions in physics. Compared to a static-field LC circuit of comparable volume and noise, the signal-to-noise ratio of this “heterodyne” approach is parametrically enhanced by ω1=ma It benefits from the very large intrinsic quality factors Qint ≳ 2 × 1011 achievable in SRF cavities [46,47], which far exceed the quality factors achievable in staticfield detectors targeting small axion masses. This broadband approach is sensitive to a wide range of axion masses without the need to scan over frequency splittings. We will show parametric estimates that illustrate its potential; detailed calculations of signal and noise are given in Ref. [39] and the Supplemental Material [49]

DETECTION STRATEGY

OVERVIEW OF SIGNAL AND NOISE

DISCUSSION