Paper detail

Annual-modulation fingerprint of the axion wind induced sideband triplet in quantum dot spin qubit sensors

We propose a phase-coherent, narrowband magnetometer for searching couplings between axions or axion-like particles (ALPs) and electron spins, using gate-defined silicon quantum-dot spin qubits. With repeated Ramsey echo sequences and dispersive readout, the qubit precession response can be tracked with sub-Hz spectral resolution. The accessible axion mass window is determined using a series of filtering protocols that take into account sensing noise, including readout errors and $1/f$ noise. We demonstrate clear evidence of sidereal modulation of the signal due to Earth's rotation, while Earth's orbital motion produces an annual amplitude envelope that generates sidebands at fixed frequency spacing $\pm Ω_\oplus$ around the sidereal component. For axion masses between $1$-$10~μ{\rm eV}$, the proposed method covers axion-electron coupling strengths $g_{ae}$ ranging from $10^{-14}$ to $10^{-10}$. Including both daily and annual modulation patterns in the likelihood analysis enhances the rejection of stationary or instrumental noise. Our results indicate that spin-qubit magnetometry can achieve sensitivities approaching those suggested by astrophysical considerations, providing a complementary, laboratory-based probe of axion-electron interactions. Although we focus on silicon spin-qubit architectures, the approach is broadly applicable to spin-based quantum sensors.