Phase-gradient metasurface enables atomic spin chirality detection for elliptically polarized laser-pumped atomic magnetometer

The powerful light field manipulation capability of metasurfaces offers a novel development perspective for the quantum precision measurement. By applying the phase-gradient metasurface (PGM) to atomic magnetometers (AMs), we have proposed and experimentally demonstrated a new type of compact single-beam elliptically polarized atomic magnetometers (EPAMs). Employing the fabricated chiral beam splitter PGM with high cross-polarization transmittance, a new atomic spin chirality detection method was devised, enabling the ultra-high sensitivity for extremely weak magnetic field measurement and achieving a high sensitivity of 2.67 pT/Hz^1/2 under an external magnetic field of approximately 10,000 nT. The new AMs combine the pumping and probing polarized light, achieving a compact design. The fabricated PGM has a size of only 3 mm × 3 mm × 0.7 mm, which is beneficial for the miniaturization and integration of AMs. This work effectively expands the application of metasurfaces in the field of quantum precision measurement, and also provides a new viewpoint for the design and development of high-sensitivity and miniaturized AMs.