Harnessing quantum materials for magnetic field sensing

Advanced research into quantum materials has allowed us to harness quantum effects on well-known materials and introduce properties which provide sensing abilities far beyond what has been possible previously.

Professor Heike Ebendorff-Heidepriem and her team are working on using diamonds with quantum properties, embedded in more conventional glass fibres, to very precisely sense changes in magnetic fields.

Heike explains "Glass fibre networks are used all over the world to carry information as they allow signals to go in one end, travel great distances without being impacted by external environments, and be accurately detected and interpreted at the other end."

"We are working on an interdisciplinary project, with collaborators at RMIT, University of Melbourne, UniSA and Defence, which marries the capabilities of glass fibres with the magnetic field sensing abilities of specially adapted diamonds. If you alter diamond by incorporating nitrogen atoms and vacancies (spaces where the carbon atoms have been removed) in the diamond’s structure, it can fluoresce red light when illuminated with green light. As the brightness of the fluorescence changes with varying magnetic field strengths, glass fibres with embedded diamond can be used for magnetic field sensing."

"This method of detection is so sensitive, it can measure small changes even against the ever-present background magnetic field of the Earth and can identify the presence and movement of large metal objects even when placed underwater or underground."

"The tricky part is putting the adapted diamond inside the glass fibre as if you heat the diamond too much it can damage the sensing properties. We have developed a process whereby it can be embedded into the glass before it is ‘stretched’ out into a fibre, allowing the diamond and its properties to survive the process whilst keeping the optical properties of the fibre accurate and consistent."

"Next, we will look at improving how we analyse the fluorescence to achieve higher levels of sensitivity and determining which type of glass is most robust under real world conditions. We will also look at whether there are differences in accuracy depending on where in the fibre the diamond is situated and whether operation changes the properties of the defect in the diamond which we are relying on for sensing."

Glass fibres embedded with diamonds in this way can be used to develop underwater fibre networks which can detect marine vessels in areas such as ports, or underground networks which can be used in contested spaces to detect vehicle movements. They also have potentially exciting applications in bio-medical thermometry and imaging.