Enhanced Rydberg-Atom Superheterodyne Detection of Hidden-Photon Dark Matter on Chips

Although hidden-photon dark matter with masses above ${10}^{-4}\mathrm{e}\mathrm{V}$ is well motivated by inflationary production, it remains largely unexplored by terrestrial experiments. Through kinetic mixing, hidden photons induce a weak oscillating electric field above $10\mathrm{G}\mathrm{H}\mathrm{z}$. We propose to amplify this signal using a compact high-frequency distributed cavity and detect it with chip-scale Rydberg-atom superheterodyne spectroscopy. Combining resonant enhancement, large dipole moments of Rydberg atoms, and long-term stable integration, this approach can probe hidden-photon dark matter in the mass range $5\times {10}^{-5}\text{–}7\times {10}^{-4}\mathrm{e}\mathrm{V}$ with sensitivities $3$–$4$ orders of magnitude beyond existing limits.