Magnetic field detection using faraday effect

Abstract

A magnetometer is provided for detecting a magnetic field of strength B using the Faraday effect. The magnetometer includes a photon emitter, a first polarizer, a prism, a second polarizer, a detector and an analyzer. The emitter projects an emitted light beam substantially parallel to the magnetic field and having wavelength λ. The prism has an interface surface and is composed of a Faraday medium having Verdet value V. The emitted light beam passes through the first polarizer and then the prism, exiting from the interface surface making an incident angle θto normal of the surface and then refracting into a secondary medium as first and second circularly polarized light beams that are separated by a small angular divergence δ. These polarized light beams have average refraction angle θ to the normal and pass through a post-selection polarizer before the detector measures a weak value Aof a photon having 'which path' operator  associated with the polarized light beams. The magnetic field strength is determined as The parameters include nas index of refraction of the secondary medium, and ε as amplification factor. The pointer rotation angle Acan be expressed as in which θand θare respectively right- and left-polarized refraction angles with the average refraction angle such that The pointer rotation angle Acan be approximated as A≈δ/2ε when 0<ε<<1. A method is provided incorporating operations described for the magnetometer.