All-Optical Wide-Field Magnetometry with Van Der Waals Quantum Sensor

Negatively charged boron vacancy $V_B^-$ centers in hexagonal boron nitride (h-BN) have attracted wide-range interests owing to their van der Waals lattice and their potentials for in-situ quantum sensing. Here we propose and experimentally demonstrate an all-optical strategy for wide-field magnetometry based on V_B^- centers. This strategy exploits the magnetically sensitive ground-state level anti-crossing (GSLAC) of V_B^- centers, which induces a strong electron spin transition between m_S = 0 and m_S = -1 states, enabling microwave-free magnetic field measurement. By monitoring the shift of GSLAC feature, the external magnetic field can be precisely determined. Using this technique, we demonstrate all-optical wide-field imaging of near-field DC magnetic field distribution from current-carrying circuits over an area of around 42 times 21 μm². An estimated photon shot-noise-limited sensitivity of 67.1 μT/sqrt{Hz} is achieved for a single pixel, which is an approximately threefold improvement over the ODMR method, along with a spatial resolution of about 1 μm per pixel. Our approach expands the applicability of V_B^- centers in quantum sensing, paving the way for robust and convenient magnetometry under extreme conditions.