Architectures and algorithms for near-future quantum computing

Background:
Quantum computation could profoundly outperform conventional computers for certain tasks, which may include prediction of chemical reactions and materials properties (thus accelerating the process of research and discovery) as well as optimization and machine learning task of great interest to industry. Many research groups around the world are therefore working towards one of the most ambitious goals humankind has ever embarked upon: realizing a real, working quantum computer. Several different physical systems, spanning much of modern physics, are being developed for this task-ranging from single particles of light to superconducting circuits-and it is not yet clear which, if any, will ultimately prove successful. But these approaches have one thing in common: the control we can achieve is far lower than the control we have over bits in conventional computers. The first generation of quantum computers will therefore be imperfect, by comparison to our reliable conventional technologies, but they will still have the potential to be vastly more powerful.

Aims:
This project is thus aimed to investigate the possible tasks that can be successfully performed even in the presence of small errors, as 1st generation quantum computers will have imperfect qubits. Our methodology will follow the approaches recently established both by Oxford (e.g. Scientific Reports volume 6, article 32940 and Phys. Rev. X volume 7, 021050) and various other groups worldwide (for one example, J. Chem. Theory Comput volume 12, 3097). This work suggests that that indeed small errors are not a "show stopper" and thus we should be able to put first generation quantum computers to work on useful tasks. The project will focus on problems that are considered natural to solve on near-term quantum computers, such as optimisation problems and chemistry simulations. Once the student is familiar with the state of the art quantum and classical methods, they will design new algorithmic protocols to solve these problems more effectively. This may include algorithms that are more resilient to errors, or that are more efficient than the existing methods. This will be achieved through a combination of 'pen-and-paper' calculations, classical numerical simulations (using Oxford's QuEST simulation package), and potentially experiments on existing quantum hardware (e.g. IBM's 20 qubit quantum computer). There is scope for the work to be either hardware specific (e.g. focused on Oxford's light-matter quantum computer), or hardware agnostic.

Resources:
It is expected that access to high performance computing will be an important part of the project, since powerful conventional computers can be used to simulate small quantum computers and predict their behavior (until we indeed have real quantum computers to operate on). For this purpose fortunately Oxford has a dedicated £800k facility and we also have potential access to the ARCHER national computing facility.

EPSRC alignment:
The work is very well aligned with at least two of the current EPSRC themes, namely
- Information and communication technologies (ICT), and
- Quantum technologies.
As explained above, the work is aimed at identifying the early practical uses of quantum technology, and is therefore potentially of high impact both within the scientific community and in the commercial spheres (nationally and internationally). While there is no industrial sponsor for this specific studentship, there are industrial sponsors for other students in the host group (e.g. QinetiQ Ltd and Quantum Motion Technologies Ltd).