Defect engineering in diamond for magnetic field mapping and gradiometry

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Nitrogen-vacancy defects in diamond have generated enormous interest in recent years for their highly coherent spin properties and convenient optical interface. Magnetometry using the electron spin in an ensemble of NV- defect has been shown to be capable of detecting fields of <1 pT Hz-1/2 such that their use as quantum field sensors is generating significant industrial interest. Companies known to be building commercial magnetometry systems with NV centres include Bosch (navigation systems), and several organisations are developing NV-based magnetic imaging systems with ~10nm resolution for biological and physical sciences. NV centres can be produced by generation of vacancies followed by thermal annealing to allow the vacancies to diffuse in the crystal and 'bind' with a substitutional nitrogen atom. In the past two years we have shown that laser processing of materials using adaptive aberration correction provides a highly controlled means of generating vacancies in a desired position in the crystal. Upon subsequent annealing the vacancies diffuse ~100 nm such that NV centres are produced with high probability in the desired location. Success probability of single NV generation in current experiments is around 30%. With iterative processing it should be possible to produce regular 3D grids of single NV centres for advanced magnetometry applications.The Project: The student will develop controlled 3D arrays of single NV centres using laser processing in Martin Booth's group in the department of Engineering. Samples will be characterised using photoluminescence spectroscopy and optically detected magnetic resonance in Jason Smith's group in the Department of Materials. Samples with cubic arrays of NV centres will be targeted. We will measure the electron spin coherence times of the NV centres to assess their suitability for magnetometry. The best samples will be used to demonstrate 3D magnetic field mapping and gradiometry.The student will benefit from working within two groups involved in the NQIT Hub and will receive extensive training in laser processing, defect characterisation and magnetometry. They will work with NQIT postdocs Patrick Salter (Engineering) and Sam Johnson (Materials). They will gain in-depth training in diamond by attending modules of the Centre for Doctoral Training in Diamond Science and Technology. We will arrange close interaction between the student and Element Six to optimise the materials towards user applications. The project falls under the theme of Quantum Technologies.