Magnetic field imaging by hBN quantum sensor nanoarray

Placing a sensor close to the target at the nano-level is a central challenge in quantum sensing. We demonstrate magnetic field imaging with a boron vacancy (⁠ $V B −$⁠) defects array in hexagonal boron nitride with a few 10 nm thickness. $V B −$ sensor spots with a size of (100 nm)² are arranged periodically with nanoscale accuracy using a helium ion microscope and attached tightly to a gold wire. The sensor array allows us to visualize the magnetic field induced by the current in the straight micro wire with a high spatial resolution. Each sensor exhibits a practical sensitivity of $73.6 μ T / Hz 0.5$⁠, suitable for quantum materials research. Our technique of arranging $V B −$ quantum sensors periodically and tightly on measurement targets will maximize their potential.