Axion Signal Search Using Hybrid Nuclear-Electronic Spin Systems

TL;DR

This paper proposes a hybrid nuclear-electronic spin system for axion detection, leveraging hyperfine interactions to enhance sensitivity and distinguish dark matter signals from backgrounds, outperforming traditional methods in certain energy ranges.

Contribution

Introduction of a hybrid sensor architecture that transduces nuclear precession into electron-spin readout, improving axion search sensitivity over existing nuclear detection techniques.

Findings

Projected to outperform direct nuclear detection by over an order of magnitude.

Achieves 5 sigma sensitivity to axion-nucleon couplings within one year.

Preserves modulation signatures for dark matter signal identification.

Abstract

Conventional nuclear magnetic resonance searches for the galactic axion wind lose sensitivity at low frequencies due to the unfavourable scaling of inductive readout. Here, we propose a hybrid architecture where the hyperfine interaction transduces axion-driven nuclear precession into a high-bandwidth electron-spin readout channel. We demonstrate analytically that this dispersive upconversion preserves the specific sidereal and annual modulation signatures required to distinguish dark matter signals from instrumental backgrounds. When instantiated in a silicon ${ }^{209} \text{Bi}$ donor platform, the hybrid sensor is projected to outperform direct nuclear detection by more than an order of magnitude over the $10^{-16}-10^{-6} \text{eV}$ wide mass range. With collective enhancement, the design reaches a $5 \sigma$ sensitivity to DFSZ axion-nucleon couplings within one year, establishing hyperfine-mediated sensing as a competitive path for compact, solid-state dark matter searches.