@article{13553, keywords = {Frequency measurement, Laser beams, Modulation techniques, Optical fields, Squeezed states, Zeeman effect}, author = {Christopher Kiehl and Thanmay Menon and Svenja Knappe and Tobias Thiele and Cindy Regal}, title = {Accurate vector optically pumped magnetometer with microwave-driven Rabi frequency measurements}, abstract = {

Robust calibration of vector optically pumped magnetometers (OPMs) is a nontrivial task, but increasingly important for applications requiring high-accuracy such as magnetic navigation, geophysics research, and space exploration. Here, we showcase a vector OPM that utilizes Rabi oscillations driven between the hyperfine manifolds of 87Rb to measure the direction of a DC magnetic field against the polarization ellipse structure of a microwave field. By relying solely on atomic measurements—free-induction decay (FID) signals and Rabi measurements across multiple atomic transitions—this sensor can detect drift in the microwave vector reference and compensate for systematic shifts caused by off-resonant driving, nonlinear Zeeman (NLZ) effects, and buffer gas collisions. To facilitate deadzone-free operation, we also introduce a Rabi measurement that utilizes dressed-state resonances that appear during simultaneous Larmor precession and Rabi driving (SPaR). These measurements, performed within a microfabricated vapor cell platform, achieve an average vector accuracy of 0.46 mrad and vector sensitivities down to 11µrad/Hz for geomagnetic field strengths near 50 µT. This performance surpasses the challenging 1-deg (17 mrad) accuracy threshold of several contemporary OPM methods utilizing atomic vapors with an electromagnetic vector reference.

}, year = {2025}, journal = {Optica}, volume = {12}, number = {1}, pages = {77-87}, month = {2025-01}, publisher = {Optica Publishing Group}, url = {https://opg.optica.org/optica/abstract.cfm?URI=optica-12-1-77}, doi = {10.1364/OPTICA.542502}, }