Multipass cell SERF atomic magnetometer based on parallel plate configuration.

We introduce a novel, to the best of our knowledge, compact multipass cell design for spin-exchange relaxation-free (SERF) atomic magnetometers, replacing conventional reflective cavities with a dual-parallel plate configuration. This adjustable planar reflector setup achieves precise control of reflection optical paths and dramatically enhances signal response, resolving the complexity of cavity design and volume increase caused by multiple reflectors in existing schemes, while having high-temperature adaptability and minimizing size and complexity. Additionally, combined with a flat-top light pump to boost atomic polarization uniformity, our system achieves 1 fT/Hz^½ sensitivity, delivering 260% improvement in signal and 200% in sensitivity over conventional designs. This streamlined, high-temperature-compatible architecture marks a significant step toward scalable, next-generation quantum sensors that unite exceptional sensitivity with practical miniaturization.