Thermal effects in solid state quantum computing

Research aim: Examine thermal effects that lead to noise, decoherence and errors in solid-state quantum bits (qubits).

The rapid development of quantum computing has seen a variety of different proposals on how to construct a quantum computer. Examples include trapped ions, photonic and neutral atoms, to name a few. However, these proposals differ widely in their implementation, and come with unique merits and limitations. Solid state, particularly, semiconducting qubits have also been proposed, and demonstrated, as a method of building quantum computers. Crucially, this implementation has the distinct advantage of the possibility to be manufactured at a large scale, and with existing CMOS (Complementary Metal Oxide Semiconductor) techniques. As well as offering other desired properties, such as long dephasing/relaxation times and high-fidelity single qubit gate operations. Nevertheless, semiconducting qubits are still susceptible to noise and decoherence. Therefore limiting their ability to perform quantum computations involving large numbers of gates etc. Generally, it is known that thermal effects play a contributing factor in generating noise and decoherence in quantum computers.

In addition to these developments, is the emergence of quantum thermodynamics as a nascent area of research. Dealing precisely with the study of thermal effects at a quantum scale. As well as more fundamental questions regarding the definition of classical thermodynamical quantities at a small scale.

The objective of this project is to characterise and explore thermal effects that lead to noise, decoherence and errors in semiconducting qubits. Find ways of mitigating them, and explore the possibility of using such effects constructively for performing quantum computations. The novelty of this project lies in these objectives and the application of quantum thermodynamics as a method for studying them, in semiconducting qubits. By understanding and controlling thermal effects, the operational temperature of semiconductor qubits may be increased. A major step required for building a scalable quantum computer. Additionally, the accuracy of quantum computations may be improved.

This project falls within the EPSRC quantum technologies theme.

A collaboration with IST Austria provides us with some of the required semiconducting quantum devices used for experiments. This is in addition to collaborations within Oxford providing knowledge and expertise regarding the broader area of quantum technologies.