Atomic Magnetometry\nUsing a Metasurface Polarizing\nBeamsplitter in Silicon-on-Sapphire

We demonstrate atomic magnetometry using a metasurface\npolarizing\nbeamsplitter fabricated on a silicon-on-sapphire (SOS) platform. The\nmetasurface splits a beam that is near-resonant with the rubidium\natoms (795 nm) into orthogonal linear polarizations, enabling the\nmeasurement of magnetically sensitive circular birefringence in rubidium\nvapor through balanced polarimetry. We incorporated the metasurface\ninto an atomic magnetometer based on nonlinear magneto-optical rotation\nand measured subnanotesla sensitivity, which is limited by low-frequency\ntechnical noise and transmission loss through the metasurface. To\nour knowledge, this work represents the first demonstration of SOS\nnanophotonics for atom-based sensing and paves the way for highly\nintegrated, miniaturized atomic sensors with enhanced sensitivity\nand portability.