Using noise to enhance quantum computation

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There are several difference models of quantum computing, including the circuit model using quantum gates, measurement based quantum computing, adiabatic quantum computing, and quantum walks. All of the theory behind these models assumes ideal noiseless operations. However, in all practical quantum hardware, interactions with the environment are unavoidable, and it is a major engineering challenge to reduce the noise, and mitigate the unwanted effects. This project takes a different approach, supported by theory showing that noise can sometimes be useful in computation. Quantum annealing is one example where cooling to very low temperatures helps to find the ground state. Quantum walks with controlled amounts of noise also retain their useful quantum properties. This project will investigate both quantum walks and quantum annealing, to characterise how and when - and how much - noise is helpful. By understanding how this works to perform useful computation, the aim is to apply the principles to other quantum computing models, and hence make use of the noise to compute, where possible. Both theoretical and computational methods will be used to model the quantum computer and noise, and the models will be tested using real quantum computers, available through the National Quantum Computing Centre, and in collaboration with experimentalists at Strathclyde.