As cheap, powerful GPS jammers proliferate, a look at some alternatives to GPS, including using supersensitive, quantum-based magnetic sensors (Christopher Mims/Wall Street Journal)

Christopher Mims / Wall Street Journal: As cheap, powerful GPS jammers proliferate, a look at some alternatives to GPS, including using supersensitive, quantum-based magnetic sensors   —  The proliferation of cheap, powerful GPS jammers has airline operators, shipping firms and militaries alike scrambling for navigation alternatives