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arXiv:2601.06816

Axion Signal Search Using Hybrid Nuclear-Electronic Spin Systems

Xiangjun Tan, Zhanning Wang

quant-phhep-exhep-phSubmitted Jan 11, 2026• Announced Jan 13, 2026• Revised Mar 21, 2026 (v2)
v1 · Jan 11, 2026v2 · Mar 21, 2026v3 · Sep 23, 2026
arXivHTMLPDF

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 $5 σ$ sensitivity to DFSZ axion-nucleon couplings within one year, establishing hyperfine-mediated sensing as a competitive path for compact, solid-state dark matter searches.

Journal reference
Phys. Rev. D 114, L051902 Published 8 September, 2026
DOI
10.1103/4rbk-zmxk

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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 209Bi{ }^{209} \text{Bi}209Bi donor platform, the hybrid sensor is projected to outperform direct nuclear detection by more than an order of magnitude over the 10−16−10−6eV10^{-16}-10^{-6} \text{eV}10−16−10−6eV wide mass range. With collective enhancement, the design reaches a 5σ5 σ5σ sensitivity to DFSZ axion-nucleon couplings within one year, establishing hyperfine-mediated sensing as a competitive path for compact, solid-state dark matter searches.
Axions are a compelling dark matter candidate suggested by theories beyond the Standard Model. The predicted axion-electron coupling and the resulting pseudomagnetic field allow for laboratory axion searches. Here we report an experimental axion search via a superconductor-spin hybrid magnetometer. A state-of-the-art broadband magnetometer with a sensitivity of sub-100 aT/Hz1/2^{1/2}1/2 at tens of kHz has been realized by coupling a ferrite spin sensor to a readout system based on a superconducting quantum interference device. The most stringent terrestrial constraints on the axion-electron coupling have been established in the frequency range 5$\sim$60 kHz. In the future, an improvement on the constraints of more than 4 orders of magnitude is foreseeable through arrays of superconductor-spin hybrid magnetometers with optimized designs. This work demonstrates the potential of superconductor-spin hybrid magnetometers in high-precision magnetic field sensing and the study of fundamental physics.
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Ultralight bosonic dark matter with masses in the meV range, corresponding to terahertz (THz) Compton frequencies, remains largely unexplored due to the difficulty of achieving both efficient signal conversion and single-photon-sensitive detection at THz frequencies. We propose a hybrid detection architecture that integrates a dielectric haloscope, Rydberg-atom transducer, and superconducting nanowire single-photon detection within a unified cryogenic platform operating at ≲1 K\lesssim 1\,\text{K}≲1K. The dielectric haloscope converts dark matter into THz photons via phase-matched resonant enhancement, achieving form factors C∼0.4C \sim 0.4C∼0.4 and loaded quality factors QL∼104Q_L \sim 10^4QL​∼104. A cold 87^{87}87Rb ensemble then coherently up-converts the THz signal to the optical domain through six-wave mixing among Rydberg states. The intrinsic directionality and narrow bandwidth (Δνatomic∼1 MHzΔν_{\mathrm{atomic}} \sim 1\,\text{MHz}Δνatomic​∼1MHz) of this process provide extra suppression of isotropic thermal backgrounds. With 10 days of integration at 0.3 K0.3\,\text{K}0.3K, we project sensitivity to the axion-photon coupling gaγγ∼10−13 GeV−1g_{aγγ} \sim 10^{-13}\,\mathrm{GeV}^{-1}gaγγ​∼10−13GeV−1 at ma∼0.4 meVm_a \sim 0.4\,\text{meV}ma​∼0.4meV, reaching the QCD axion band and opening the THz window for searches of both axion and dark photon dark matter.
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