High-sensitivity nanoscale quantum sensors based on a diamond micro-resonator

Abstract Nitrogen-vacancy centers have demonstrated significant potential as quantum magnetometers for nanoscale phenomena and sensitive field detection, attributed to their exceptional spin coherence at room temperature. However, it is challenging to achieve solid-state magnetometers that can simultaneously possess high spatial resolution and high field sensitivity. Here we demonstrate nanoscale quantum sensing with high field sensitivity by using on-chip diamond micro-ring resonators. The ring resonator enables the efficient use of photons by confining them in a nanoscale region, enabling the magnetic sensitivity of 1.0 μT/√Hz on a photonic chip with a measurement contrast of theoretical limit. We also show that the proposed on-chip approach can improve the sensitivity via efficient light extraction with photonic waveguide coupling. Our work provides a pathway toward the development of chip-scale packaged sensing devices that can detect various nanoscale physical quantities for fundamental science, chemistry, and medical applications.