Stokes polarimetry and magnetometry using a thermal Rb vapour in the Voigt geometry with large magnetic field

Abstract

We present investigations of magneto-optical phenomena using a Rb thermal vapour in large magnetic fields. At this point, in the hyperfine Paschen-Back regime, optical transitions can be separated by more than their Doppler-broadened linewidth, providing a high level of control over the atomic system and a simpler theoretical model for studying atom-light-magnetic field interactions. In this context, we study the spectra of Rb at magnetic fields of T and T in the Voigt geometry. In both cases we find excellent agreement between experimental and theoretical absorption spectra. With the T field we also study polarisation changes induced in the light by the atoms subject to a large magnetic field. Using this approach, we consider the practical applications of our system as a vector magnetometer. We present a scheme that eliminates most sources of systematic errors in the measurement of the field strength by using pairs of transitions that cancel excited-state terms in the energy shifts. Finally, we extend the concepts and ideas investigated to an application in precision thermometry. We discuss how good understanding of the spectra and the magnetic field strength potentially allow detection of small differences in different spectral features, which could then be traced to the effect of the Boltzmann factor, , on the atomic populations.