Quantum stereomagnetometry with a dual-core photonic-crystal fiber

A monolithic dual-core photonic crystal fiber (PCF) probe employing an integrated nitrogen-vacancy diamond microcrystal and microwave transmission line is shown to enable highly sensitive dual-channel vectorial magnetic field measurements by means of optical detection of magnetic resonances with both fiber cores. Reliable detection of microscale spatial magnetic-field variations on the order of 10 μT is demonstrated with a PCF probe possessing a core-to-core separation of 6 μm. Such a fiber probe is shown to provide a powerful tool for three-dimensional vectorial mapping of weak magnetic fields emanating from spatially localized objects.