Quantum diamond microscopy with optimized magnetic field sensitivity and sub-ms temporal resolution.

Quantum diamond magnetometers using lock-in detection have successfully detected weak bio-magnetic fields from neurons, a live mammalian muscle, and a live mouse heart. This opens up the possibility of quantum diamond magnetometers visualizing microscopic distributions of the bio-magnetic fields. Here, we demonstrate a lock-in-based widefield quantum diamond microscopy, achieving a mean volume-normalized per-pixel sensitivity of 43.9 nT μ m 1.5 / H z 0.5 . We optimize the sensitivity by implementing a double resonance with hyperfine driving and magnetic field alignment along the ⟨ 001 ⟩ orientation of the diamond. Additionally, we show that sub-ms temporal resolution (∼ 0.4 ms) can be achieved while keeping the per-pixel sensitivity at a few tens of nanotesla per second using quantum diamond microscopy. This lock-in-based diamond quantum microscopy could be a step forward in mapping functional activity in neuronal networks in micrometer spatial resolution. [ABSTRACT FROM AUTHOR]