PhD Projects

We would love to hear from you if you are interested in a PhD position. Please get in touch and we can discuss options. Further details of possible opportunities are given below:

The operation of a modern design of a solar cell consists of three stages: light absorption, movement of electronic excitation, and charge separation. We recently showed that the rate of the first of these, light absorption, can be markedly improved in a symmetric ring of molecules by exploiting quantum interference [1]. In this project you will consider both light absorption and exciton transport, and probe the extent to which quantum mechanical models can be used to improve the operation of solar cells. You will go beyond idealised designs to look at realistic quantum systems. You will focus on systems that are available for immediate testing in the laboratories of collaborators - for example, semiconductor quantum dots or organic molecules.

You will work to understand how these systems interact with their environments, and model the combination as open quantum systems. This will be done using a variety of simple and more sophisticated techniques, as it becomes clear which approximations can be made. The final aim of the project will be to propose an experiment in which a clear signature of enhanced light absorption could be seen.

[1] Superabsorption of light via quantum engineering, K. D. B. Higgins, S. C. Benjamin, T. M. Stace, G. J. Milburn, B. W. Lovett and E. M. Gauger, Nature Communications 5 4705 (2014)

  

Recent experiments on photosynthetic complexes reveal the possible presence of quantum coherence between excitations on different parts of the protein complexes involved. It has been conjectured that these quantum correlations may lead to enhanced energy transfer, and thus to more efficient solar cells.

In this project, you will explore the interplay of quantum and classical mechanisms for moving electronic energy around networks of molecules. On the one hand, quantum correlations can lead to constructive interference between different parts of the network, leading to a faster transport of energy. On the other hand, such correlations may lead to destructive interference, and cause excitations to get stuck. Classical hopping may relieve this problem. You will predict the optimal balance of classical and quantum processes that lead to the highest rate of energy extraction from the network. You may need to explore the role of length scale, network topology, and use thermodynamic concepts to address this problem.

The project will be in collaboration with theorists at the University of Oxford, and may be tested in the laboratories of collaborators both in St Andrews, and at the Universities of Oxford and Cambridge.

  

Quantum computing has undergone something of a revolution in recent years. From being a technology that only a few thought might be ever be realized, a small scale computing device is now a realistic target in the next five years. This has been driven by remarkable recent progress in both theory and experiment. In particular, it is now established that the coherence time of single qubits in solid state systems is many orders of magnitude longer than that required to execute a simple logic gate. The timing is now perfect to develop a detailed blueprint for how to scale up from one to many qubits. In particular, we must gain a detailed understanding of how to describe a system of several coupled qubits interacting with a common environment. In this situation, many of the more straightforward approximate approaches to modelling open quantum systems fail. You will therefore exploit more sophisticated, and accurate, methods, such as those based on Feynman’s path integral formulation of quantum mechanics, to make predictions about the dynamics of quantum registers.

  

Post-doctoral positions

While we do not have any positions available at present, Brendon is happy to advise with applications for fellowships. Some relevant links are below. Other schemes exist, particularly international.

Royal Society Dorothy Hodgkin Fellowship

The Royal Commission for the Exhibition of 1851 Fellowships

Royal Society Newton International Fellowships

Leverhulme Trust Early Career Fellowships

Marie-Sklodowska-Curie Fellowships

Royal Society University Research Fellowship