Towards quantum-enhanced flow sensing using nitrogen-vacancy (NV) centers in diamond

Nitrogen-vacancy (NV) centers have garnered significant interest in the past decade as a versatile platform for quantum-based sensing. These vacancies are point defects within a diamond lattice whose electron spin-states are highly sensitive to external perturbations such as temperature, strain, magnetic fields, and electric fields. NV center-based sensors measure the changes in the spin-states in either an individual or ensemble of NV centers to deduce information about the parameter of interest. Changes in the spin-states are most often observed using the photoluminescence generated by electronic state transitions in the form of optically detected magnetic resonance (ODMR). Because the spin-state can be manipulated and read at room temperature, NV center-based diagnostics are becoming an increasingly accessible option for nanoscale sensing. Despite the rapid development and proliferation of NV center-based sensing protocols, these measurement capabilities have yet to be fully adopted by the fluid mechanics community. Here, we present our recent progress towards implementing a nanoscale magnetometry and thermometry system using a continuous-wave ODMR and discuss the outlook for applying this form of sensing to problems in fluid mechanics.