Dark Matter Detection through Rydberg Atom Transducer

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 lesssim 1 K. The dielectric haloscope converts dark matter into THz photons via phase-matched resonant enhancement, achieving form factors C sim 0.4 and loaded quality factors Q_L sim 10⁴. A cold 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 $Δν_atomic sim 1 MHz$ of this process provide extra suppression of isotropic thermal backgrounds. With 10 days of integration at 0.3 K, we project sensitivity to the axion-photon coupling g_aγγ sim 10^-13 GeV^-1 at m_a sim 0.4 meV, reaching the QCD axion band and opening the THz window for searches of both axion and dark photon dark matter.