Quantum Operations and Imaging Using Highly Coherent Scanning Probe Spins

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Optically active spin-defects, such as the nitrogen vacancy (NV) centre in diamond, can be used as powerful tools for quantum sensing, magnetic field imaging and quantum computation.By incorporating NV centres at the tip of solid-state scanning probes, NV centres have been used as sensitive magnetic field sensors with nanoscale spatial resolution. The NV centre can then be scanned over the surface of a magnetic sample and the consequent interaction between the NV centre and the magnetic field can be measured using optical light and resonant microwaves. As well as quantum sensing and imaging, NV centres on scanning tips can be used for the real-isation of surface-code quantum computation. Scalable quantum computing architectures require the quantum interaction between two or more quantum bits (qubits) to be highly correlated, i.e. the realisation of quantum entanglement. The movable probe would allow the NV centre in the tip to couple near-surface qubits in the sample, entangling them and allowing for the implementation of local quantum operations.This project will make use of a new operational state-of-the-art scanning and imaging instrument available to us in the London Centre of Nanotechnology. Initially this instrument will be used to image interesting samples to biology and condensed matter physics, such as novel magnetic materials and spin-labelled biological molecules. The stability of near-surface NV centres, as well as possibly silicon carbide defects, will be investigated and the fabrication technique willbe optimised to create defects with superior spin properties. This instrument can also be used to start introductory work on achieving spin-spin coupling and entanglement between donor spins in a material using a movable probe spin.