Atomic Physics2026-03-091 minarXiv:2603.08594expressA Compass That Hears AtomsMagnetic fields are invisible, but they can be heard. Rubidium atoms inside a glass cell respond to them like strings to a bow: radio waves make them oscillate between energy states.Thanmay S. Menon·Dawson P. Hewatt·Christopher Kiehl·Michaela Ellmeier·Svenja Knappe·Cindy A. RegalHendrik LorentzJames Clerk MaxwellFritz Zwickymagnetic fieldNMR spectroscopypolarimetryradarradio astronomy👍👎☆SimplePopularAdvanced