Probing millicharged dark matter with magnetometer coupled to circuit

Abstract

We present a novel approach to detect millicharged dark matter (mDM) by using a high-sensitivity magnetometer coupled with resonant and broadband readout circuits. In an external magnetic field, the interaction between mDM and the photon field introduces an effective current corresponding to the mDM’s annihilation into photons that produces a faint oscillating magnetic field signal, with a frequency uniquely determined by twice the mDM mass. By calculating the expected signal for two experimental configurations—toroidal and solenoidal magnetic fields, we show the potential to explore the uncharted regions of mDM parameter space. Our analysis establishes unprecedented constraints on the mDM coupling constant across the mass range of 1 × 10⁻¹² to 6 × 10⁻⁸ eV, surpassing existing experimental limits by up to 12 orders of magnitude at most.