Broadband interferometry-based searches for photon-axion conversion in vacuum

Abstract: A novel experiment is introduced to detect photon-axion conversion independent of the dark-matter hypothesis in a broad mass-range called WISP Interferometer (WINTER). The setup consists of a free-space Mach-Zehnder-type interferometer incorporating an external magnetic field and vacuum in one of the arms, where photon-axion mixing occurs via the Primakoff effect and is detected through changes in amplitude. The expected axion-induced signal is then modulated by polarization changes. The experiment is designed to integrate a Fabry-P\'erot cavity with a finesse of $10<sup>{5}$ that will be operated in a vacuum environment, significantly enhancing the sensitivity. The setup is sensitive to photon-axion coupling strengths values $g_{a\gamma\gamma}\gtrsim 5.5\times10<sup>{-15}$ $\text{GeV}<sup>{-1}$ for axion masses up to 84.8 $\mu$eV