Space-Variant Polarization Distribution Mitigates AC-Stark Shifts in a SERF Atomic Magnetometer

Emerging biomagnetic imaging requires compact optical pumping magnetometer (OPM) arrays that enable high spatial resolution with remarkable sensitivity. In such devices, atomic pumping fundamentally depends on conventional optical systems, yet realizing diverse pumping modalities persists as a critical challenge─particularly in integrated applications. In this study, a space-variant polarization distribution (SPD) pumping source is achieved and integrated with an atomic magnetometer for the first time. Our method enables modification of optical polarization within a 3 × 3 × 3 mm^{3 87}Rb micro-vapor cell to spatially separate the atomic pumping and detection regions, resulting in a 56% mean (75% maximum) reduction in the AC Stark effect compared with the conventional scheme. Experiment results demonstrate a 20.1 fT/Hz^1/2 sensitivity and a 52 Hz bandwidth with a dynamic response range of ±3 nT, which is comparable to the state-of-the-art chip-scale OPMs. By leveraging the SPD pumping method, various atomic devices with a diffusion-pumping scheme are able to achieve chip integration, which further paves the way for the development of high-spatial-resolution biomagnetism imaging and portable atomic sensing applications.