Speaker
Description
Atomic magnetometers with magneto-optical signals based on Zeeman effect can achieve high sensitivity and accuracy in low magnetic fields, where the Zeeman effect is linear. In magnetic fields that exceed the Earth’s magnetic field (~0.5 G), the nonlinear Zeeman (NLZ) effect introduces errors in magnetic field measurements. The NLZ effect does not affect $^{87}$Rb ground-state sublevels with total angular momentum $F_g=2$ and magnetic quantum number $m_{F_g}=±2$ even at high magnetic field values. Acosta et al. [1] created coherences between these two sublevels by modulating the frequency of an exciting laser at twice the Larmor frequency, creating hexadecapole $(Δm_F=±4)$ and quadrupole $(Δm_F=±2)$ moment in the angular momentum distribution of the $^{87}$Rb atoms. To eliminate the quadrupole moment, which exhibits NLZ effect, the laser modulation’s phase is shifted by π to destroy the quadrupole moment in such a way as to retain the hexadecapole moment. This specially prepared state was observed by measuring magnetic-field-dependent rotation of a linearly polarized laser beam that passes through the rubidium vapour. We plan to adapt this technique to measure the hexadecapole moment influence on fluorescence signals and study the effect of relaxation on the signal amplitudes using a theoretical model. We will report on the progress of theoretical modelling and describe the experimental setup.
We thank the Latvian Council of Science for support under Project No. Lzp-2023/1-0173 “Novel approach to improving accuracy and sensitivity of atomic Rb magnetometers”.
[1] V. M. Acosta et al., Opt. Express, 16, 11423 (2008)
