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Abstract
Over the past several decades, quantum information science research has proven its importance to the development of quantum computing. Research groups around the world are working towards the highly ambitious technological goal of building a quantum computer, which would dramatically improve computational power for particular tasks.
This Ph. D dissertation focuses on the development of quantum computers based on the single-electron spin bound to a phosphorus atom, implanted deterministically in silicon. It begins with the transport spectroscopy of a phosphorus atom in silicon using a double-gated nanoscale field-effect-transistor. Here, we resolved the transitions corresponding to two charge states successively occupied by spin-down and spin-up electrons. The charging energies and the Landé g-factors were consistent with expectations for donors in gated nanostructures.
Next, we demonstrated single-shot readout of an electron spin in silicon using the spin to charge conversion technique. The architecture used here consisted of a silicon quantum dot as a charge sensor nearby the implanted donor. The device exhibited a spin lifetime of ~6 seconds at a magnetic field of 1.5 Tesla and a spin readout fidelity better than 90 per cent.
The next challenge is to demonstrate coherent control of the electron spin to enable qubit state initialisation and manipulation for quantum computing. A chapter is devoted to the comparison of local and global electron spin resonance experiments in which the electron spin can be controlled by introducing an oscillating magnetic field created using a microwave frequency signal.
Quantum information research promises more than just computing. It has also helped develop the field at quantum metrology, in which current and charge can be measured with higher precision than is otherwise possible. Towards the end of this report a chapter is dedicated to the progress in using our silicon quantum dot nanostructures as a test-bed for a current source suitable for the requirements of current metrology. In this experiment we observed the charge induced by single-electron transfer with a relative error in the order of 1/1000.