A miniaturized atomic magnetometer enabled by cascaded metasurfaces

Driven by increasing demand for portable magnetic field detection in multiple application scenarios, optically pumped atomic magnetometers (OPAMs) are rapidly advancing toward smaller, portable designs, with the single-beam elliptically polarized architecture offering inherent compactness due to its simplified optical path. However, traditional implementations that use bulky multiple waveplates for polarization conversion fundamentally hinder system miniaturization. This study proposes and experimentally validates a new scheme for a chip-scale integrated OPAM. The scheme is based on a ³⁹K atom system with an Mx-mode, single-beam configuration. Its core innovation lies in employing a polarization-independent cascaded metasurface to replace the traditional multi-component polarization optics system with a monolithic device. Experiments demonstrate that this scheme, under a 10,000 nT magnetic field, maintains a sensitivity comparable to that of a commercial waveplate-based system (approximately 8.36pT/Hz^1/2 in the 70–90 Hz band) while achieving a reduction in the core optical module volume of over 60% and keeping polarization control accuracy within 3%. This work successfully verifies the feasibility of the metasurface-based approach for realizing miniaturized, manual-alignment-free optical pumping, thereby paving the way for and laying a key technical foundation for the eventual realization of fully chip-integrated, field-deployable quantum magnetometers.