Field-of-View-Breaking Localization of Magnetic Source Using Quantum Sensor

The localization and tracking of tiny magnetic source hold great potential for applications in the fields of medical and scientific research. However, cross-order-of-magnitude localization using millimeter sensor is an open problem. In this article, we proposed a precise localization method for the tiny magnetic source that breaks through the limited field-of-view of the optical quantum sensor imaging. The position of the magnetic source is uniquely resolved by the construction of a magnetic gradient tensor (MGT) based on the vector magnetic field (2.7
$\times $
2.7 mm, pixel size:
$3.45~\mu \text{m}$
) obtained by nitrogen-vacancy (NV) color centers in a diamond. A 3 mm diameter magnetic source is accurately located within a spatial range of 5 cm with a mean error of 8%. In addition, the limitations and influencing factors of the NV-MGT localization method are theoretically discussed. The results provide insight into the localization of tiny magnetic sources and extend the application of quantum sensor.