Fig. 1. Schematic of the dual-beam magnetometer. λ/2, half-wave plate; BS, beam splitter; PBS, polarization beam splitter; PD, photodetector.

Fig. 2. Experimental setup of the dual-beam SERF magnetometer for alkali-atom density measurement and control based on light absorption. DA, differential amplifier; DAQ, data acquisition; TIA, transimpedance amplifier; BS, beam splitter; PBS, polarization beam splitter; PD, photodetector; λ/2, half-wave plate; λ/4, quarter-wave plate.

Fig. 3. Comparison between measured values and theoretical values from saturated vapor pressure formula.

Fig. 4. Relationship between the measurement sensitivity of alkali-atom density and the light-frequency detuning Δν.

Fig. 5. Fitting result of the comparative experiments at different temperatures and light intensities.

Fig. 6. Variations of the alkali-atom density and temperature over time.