Magnetometry has been widely used in geological surveys, and it’s been one of the most successfully demonstrated methods for unexploded ordnance (UXO) detection and discrimination. The objective of this project is to transform the existing magnetometry technology by using a quantum sensor array as a vector magnetometer with improved sensitivity, thus enabling highly sensitive and airborne detection of underwater UXO detection. The quantum magnetometer with a pulsed control and sensing scheme will be isolated from operational noise, thus enabling UXO detections on versatile platforms such as an unmanned aerial vehicle (UAV) for high throughput surveys. This project will improve the technical readiness level of the quantum vector magnetometer from an experimentally validated level 4 to potentially level 6 for a prototype demonstration in a relevant environment. This will allow the project team to develop further a transitioning stage for actual deployment and mission operations.

The innovative quantum vector magnetometer is based on negatively charged nitrogen-vacancy centers; a unique type of color center formed by permanent atomic-level defects in a diamond. The project team will demonstrate the capability of mapping Earth field anomalies caused by UXOs acting as magnetic dipoles, and the project team will also evaluate its ability to sense electromagnetic induction (EMI) responses from metal objects. The project team will first optimize an existing highly sensitive quantum vector magnetometer in the laboratory and integrate it onto a circuit board with microwave antennas and a radio frequency signal chain. The project team will then apply an optimized microwave control sequence to enhance the sensitivity further and isolate it from vibrational noises. The project team will further integrate the optical and microwave components into a compact form factor for testing and validation. In the end, the project team anticipates having a highly sensitive but compact device with a high dynamic range capable of integration with a larger platform such as a UAV for high throughput surveys.

The sensitive vector magnetometer will allow high throughput air-borne magnetic field survey, imaging, and discrimination of underwater UXO without interference from water absorption and distortions, and vibrational noises. The further work will extend their use in EMI detections of magnetic susceptibility as well because of their high operating bandwidth. The project team can foresee that the sensor they are working on will be capable of multimodal underwater identifications including sensing modes in terms of field gradience, temperature, radio/audio signals, and chemicals, thus having a broad impact on Department of Defense missions. The results from this work will greatly expand the capability to cost-effectively characterize munition response sites with shortened flight times and to help integrate various advanced technologies into a compact platform.