Multi-frequency composite pulse sequences for sensitivity enhancement in hexagonal boron nitride quantum sensor

Abstract A negatively charged boron vacancy ( V B − ) in hexagonal boron nitride (hBN) has recently started to be used as a magnetic sensor. However, V B − has magnetic resonance spectra broadened by hyperfine interactions, which decreases the signal contrast and thus degrades the magnetic field sensitivity. Here we propose multi-frequency composite pulse sequences to enhance the contrast of the measurement signal in the Rabi oscillation. We demonstrate that the sequence using five microwave frequencies enhances the signal contrast, improving the sensitivity by a factor of 2.3 compared to the conventional sequence.