Demonstration of an interferometric technique for measuring vacuum magnetic birefringence with an optical cavity

Vacuum magnetic birefringence (VMB) is an effect predicted by quantum electrodynamics, in which the vacuum behaves as a non-linear optical medium and exhibit a birefringence in the presence of a magnetic field. In this work, an interferometric scheme is introduced to measure this effect for the first time by sensing the changes in the frequencies of fields stabilized to the resonances of an optical cavity. Results are presented from a prototype setup with this novel sensing technique implemented on a 19 m test cavity without a magnetic field. We propose using this scheme for a measurement of VMB with a 245 m long optical cavity and a string of 24 superconducting magnets, arranged for the ALPS II experiment. In this manuscript we examine potential sources of noise in the prototype, and project these results in terms of the sensitivity of the full-scale experiment.