NV centres in diamond for magnetic field quantum sensing

Nitrogen-Vacancy (NV) centres in diamond have been shown to possess a quantised energy structure that allows for a number of macroscopic parameters to be measured with a high level of sensitivity. The process of sensing magnetic fields can be achieved through the behaviour of the NV centre’s electron spin triplet states using the separation of field-dependent and independent states, inferred by applying a microwave frequency to drive transitions. Observation of the states is achieved through optical pumping and stimulated emission, where the intensity of the fluorescent emission and frequency of the applied microwaves relates to the magnitude of the magnetic field the NV centre experiences. The optical method of sensing can be facilitated using optical fibres in which NV diamond particles are embedded between the core and outer fibre layers, leading to a robust platform for further practical applications with strong resistance to external interference.