Application Description

Ensembles of nitrogen vacancy (NV) centers in diamond make useful sensors of DC and AC magnetic fields, thanks to their ability to perform sensitive, wide field-of-view magnetic imaging at ambient conditions. By using different techniques, experimentalists can use NV centers to sense frequencies from DC up to several GHz with bandwidths of up to roughly 100 kHz. The key figure of merit for this application is the sensitivity, which specifies the weakest field strength that can be detected with a signal-to-noise ratio (SNR) of unity in a given bandwidth. Compared to single NV centers, ensembles comprising N different NV centers in the sensing volume benefit from a √N improvement to the sensitivity, allowing them to reach sensitivities at the level of pT/√Hz.

Furthermore, ensembles of NV centers can be used for wide-field magnetic imaging at room temperature. As NV centers have four possible orientations within the diamond crystal, ensembles can even be used for vector magnetometry. Sensing with NV centers typically relies on optical detection: the strong signals generated by ensembles of NV centers make it possible to use photodiodes instead of the more expensive and cumbersome avalanche photodiodes. The ambient operating conditions and high sensitivities of ensembles of NV centers, alongside their wide frequency range and strong signals, thus make them a powerful tool for magnetometry and other types of sensing.