Dead-zone-free single-beam atomic magnetometer based on free-induction-decay of Rb atoms.

This article focuses on the development of a dead-zone-free free-induction-decay (FID) atomic magnetometer using rubidium-87 (^87Rb) atoms. By employing a single laser beam with equal linear and circular polarization components and modulating its intensity at a low duty cycle (~20%), the researchers achieved synchronous optical pumping at both the Larmor frequency (Ω_L) and its second harmonic (2Ω_L), enabling detection of magnetic fields from all directions without dead zones. The magnetometer demonstrated a sensitivity ranging from 3.2 to 8.4 picotesla per root hertz (pT/√Hz) across all spatial orientations, with a simple experimental setup that does not require lock-in detection. This approach offers potential for miniaturized atomic magnetometers applicable in fields such as geomagnetic sensing and biomedical imaging.