High-temperature lithium atomic magnetometry by symmetric hyperfine coherent population trapping resonances

A glass lithium vapor cell is an atomic sensor operating at high temperature. The longitudinal magnetic-field strength is measured by coherent population trapping (CPT) in ground-state hyperfine levels. Two linearly polarized light beams are polarized orthogonally to each other. The difference of optical frequencies is tuned to generate a dark state. Additionally, a few light modes of equidistant frequency spacing are generated by modulating the difference frequency. The symmetry of the light modes and the energy levels enables simultaneous measurement of the hyperfine splitting frequency of the ground state and the magnetic-field strength. Tuning the optical frequency difference to the central CPT resonance, a sensitivity of 15 pT/root Hz is achieved. The time response and the sensitivity of the CPT magnetometry are studied by changing the cell temperature, the laser power, the frequency separation of the light modes, and the Zeeman frequency. (C) 2021 Optical Society of America

Automated summary

The article discusses a glass lithium vapor cell atomic sensor operating at high temperatures using coherent population trapping (CPT) to measure magnetic-field strength in hyperfine levels. By tuning the difference of optical frequencies to generate a dark state, simultaneous measurement of hyperfine splitting frequency and magnetic-field strength is achieved. The CPT magnetometry's time response and sensitivity were studied by varying parameters like cell temperature, laser power, frequency separation of light modes, and Zeeman frequency.