Utility of near- and long-term quantum computers

Context: Many research groups around the world are getting close to realizing the first generation of a profoundly powerful new class of technology: quantum computers. Building such a machine means learning to control qubits (quantum bits). Different approaches are being tried, with qubits embodied as individual atoms, or nanostructures in solid state structures, or superconducting loops. But all have one thing in common: the control we can achieve is far lower than the control we have over bits in conventional computers. The early generations of quantum computers will therefore be imperfect, by comparison to our reliable conventional technologies, but they will still have the potentially to be vastly more powerful. Methods such as error mitigation and the powerful and general approach of quantum error correction can suppress errors to the level that complex algorithms become possible. These ideas are best understood within the context of the physical architectures and hardware-level operations that a given technology provides. 

Project: This theory project will use both analytic techniques and conventional supercomputers to understand the behaviour of both early- and late-generation quantum computers, including their limitations and flaws. Key themes within the project will be drawn from the following areas (a typical project will involve more than one theme, but not all of the following). A current focus in the group is to identify applications, such as novel materials and chemistry discovery, which may be able to run successfully on relatively near-term quantum computers despite their imperfections. Other foci include designing error correction protocols to optimally use specific kinds of architecture (for example, ion traps versus superconducting arrays), and efficient 'decoders' i.e. the classical software that monitors a quantum computing and deduces the nature of errors as they occur.  A final theme is the development of simulation software that can efficiently model small quantum devices, or larger devices within approximations.

In the UK there is a high level of government support for such efforts, for example through the "National Quantum Strategy Missions" and the National Quantum Computing Centre at Harwell near Oxford. This project therefore falls within the EPSRC quantum technologies research area.

Resources available to the project include the Oxford ARC (Advanced Research Computing) facility and there are collaboration opportunities with the numerous experimental efforts in Oxford which span multiple departments and quantum modalities (ionic, atomic, superconducting and semiconductor). Primary support will come from Prof. Simon Benjamin (Oxford) and the host group includes 10 individuals working in related areas. The groups of  Professor Balint Koczor in Oxford’s Maths Institute and Dr Zhenyu Cai's theory team in Engineering will also be collaborating, and those two team leaders are potential cosupervisors on this project.