Imperfect quantum technology: Exploiting 1st generation computers

This theory project will use both analytic techniques and conventional supercomputers to predict the behaviour of 1st generation quantum computers including their limitations and flaws. A current focus is to identify applications, such as novel materials and chemistry discovery, which may be able to run successfully on a near-term quantum computer despite its imperfections. This is a timely topic: If we are to make use of the computers that emerge in the next few years (such as Google's "quantum supremacy" device) we need to map the detailed architectures and error models to the desired application through error mitigation protocols. This project therefore falls within the EPSRC quantum technologies research area.

Precursor research to this project is described in the online manuscripts at the arxiv.org site as follows: arXiv:1808.03623, arXiv:1807.04973, arXiv:1807.02467, arXiv:1806.05707, arXiv:1804.03023, and arXiv:1802.08032. The novel techniques here include the "imaginary time variational technique" which the host group has pioneered. This is a method according to which the (more conventional) gradient vector for an energy-landscape-descent problem is adjusted to allow for the relationship between the parameter space and the problem space, i.e. Hilbert space. Prior work has indicated that this method, while seeming at first to be more computationally costly, is in fact more efficient since it is less prone to local minimum traps and related issues. The new project would be a continuation of this work, and would involve both analytic and numerical research and liaising with various experimental group within and outside of Oxford. A primary early focus will be on error mitigation, as per e.g. arXiv:1807.02467. Both the "extrapolation" and the "quasi-probability" technique will be investigated, initially with a view to assessing the impact of non-Markovian errors i.e. errors which are correlated in time, or space, or both. This is a crucial issue since such errors are common in reality but often overlooked in prior theoretical studies.

Resources available to the project include the Oxford ARC (Advanced Research Computing) facility and specifically the ~£1M cluster of compute and GPU nodes that have been acquired as part of the NQIT hub and will be acquired as part of the new Hub in Quantum Computing and Simulation. Primary support will come from Prof. Simon Benjamin (Oxford) and the host group includes 10 individuals working in related areas including postdoc Dr Balint Koczor at Oxford.

There is no specific industry commitment for this project, but BP (who have supported a 1-year PDRA in the area) have indicated that they would be interested in opportunities to provide support to student(s) working on a project such as this. Also it is likely that the project will involve use of IBM's prototype hardware, which group members have privileged access to due to Oxford's membership of the IBM-Q organisation.