High Precision Ellipsometry: Limits on Magnetically Induced Faraday Rotation from Polarized ³He Atoms and Beyond

Faraday rotation is a powerful tool in a large variety of physics applications. Most prominently, Faraday rotation can be used in precision magnetometry. This talk will focus on our results on detecting gyromagnetic Faraday rotation on a dense, hyperpolarized ³He gas target. Theoretical calculations predict the rotations of linearly polarized light due to the magnetization of spin-1/2 particles on the order of 10⁻⁷ radians for such targets. A sensitive apparatus consisting of a polarized 3He target and a multipass cavity was constructed achieving a sensitivity for the detection of optical rotations on the order of 10⁻⁸ radians. Although the expected results are well above the sensitivity for the given experimental conditions, no nuclear-spin-induced rotation was observed. The present status and new applications will discussed.