Peking University and Mainz Demonstrate a Levitated Magnet Magnetometer at 32 Femtotesla per √Hz and Room Temperature in Science, the Signal Class of Undersea Magnetic Anomaly Detection

Physicists at Peking University and Johannes Gutenberg University Mainz published a levitated magnet magnetometer in Science whose preprint reports 32 ± 3 femtotesla per root hertz at approximately 305 Hz, at room temperature inside a four-layer cylindrical magnetic enclosure, without cryogenics. Earth-strength background-field tolerance does not establish unshielded sensitivity. The response FWHM is approximately 0.025 Hz, with sensitivity of approximately 1 nT/√Hz below 15 Hz. We read the physics against magnetic anomaly detection of submarines, from the P-3 tail stinger to the Strategic Capabilities Office's throwaway sensor drone, and set out what stands between a quiet optical bench and a sonobuoy-launched sensor, including suitable low-frequency performance or demonstrated signal modulation.