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 105 that will be operated in a vacuum environment, significantly enhancing the sensitivity. It is projected to reach the DFSZ theoretical line with photon-axion coupling sensitivities down to gaγγ≃3.7×10−14GeV−1 for axion masses up to 380 μeV.
@article{arxiv.2509.16725,
title = {Broadband interferometry-based searches for photon-axion conversion in vacuum},
author = {Josep Maria Batllori and Dieter Horns and Marios Maroudas},
journal= {arXiv preprint arXiv:2509.16725},
year = {2026}
}