Mainz 2026 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 44: Laser Technology and Applications
Q 44.8: Talk
Thursday, March 5, 2026, 12:45–13:00, P 2
Probing Vacuum Magnetic Dichroism with Precision Interferometry — •Aaron Spector1 and Laura Roberts2 — 1Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany — 2Max-Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut) and Leibniz Universität Hannover, Hannover, Germany
An exciting new frontier in the search for physics beyond the standard model is emerging as experiments are using precision interferometry to probe the vacuum magnetic dichroism effect. Here, light propagating through a vacuum could experience additional polarization dependent optical losses in the presence of a magnetic field as some of its energy is transferred to hypothetical fields such as axion-like-particles, millicharged fermions, and dark matter ``chameleons.'' In this talk, we propose a new method to test this effect by continuously characterizing the complex reflectivity of an optical cavity for polarization states aligned parallel and perpendicular to a modulated external magnetic field. Using this technique, it could be possible to disentangle the changes of conventional loss channels in an optical cavity, such as scattering and absorption at the mirror coatings, from sources induced by new physics interacting with the magnetic field. I will also discuss the discovery prospects of a setup utilizing the ALPS II infrastructure (24 HERA dipole magnets each providing 5.3 T magnetic fields for a length of 8.8 m) along with a 246 m long cavity and give a status report of a prototype setup implemented on a 19 m long cavity.
Keywords: Laser Interferometry; Vacuum Magnetic Dichroism; Axions; Physics Beyond the Standard Model; Vacuum Magnetic Birefringence