Exploiting first-generation quantum computers

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Context [note, this Context text has been used in prior JeS descriptions]: Prof Benjamin's group (qtechtheory.org) has an ongoing theory project which uses a combination of analytic techniques together with conventional supercomputers to predict the behaviour of 1st generation quantum computers including their limitations and flaws. The aim is to find applications for these powerful but imperfect systems. 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: qubits may be individual atoms, or nanostructures in diamond, superconducting loops, or even conventional silicon chips redesigned to host qubits. 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 first generation 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. The focus of this theory project is on understanding the capabilities of 1st generation quantum computers including their limitations and flaws. One key goal of the project 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 may include exploring the adjacent goal of improving "quantum error mitigation" which are protocols that enable quantum computers to behave in a more stable and useful manner for multiple applications. Additionally, although the focus of the project is on early quantum computers, another goal within scope will be to explore the anticipated transition from 1st generation machines to later (more mature) generations through the concept of 'fault tolerance'. The research will include both analytic "pen and paper" theory as well as numerical modelling using conventional computers to simulate quantum machines; for the latter goal the group has the QuEST family of software packages that allow efficient simulation to the extent possible. As increasingly useful quantum prototype hardware becomes available online, it is likely that these systems (which have hitherto been too small and imperfect to be useful) will also be used.Resources available to the project include the Oxford ARC (Advanced Research Computing) facility and specifically the ~£0.5M cluster of compute and GPU nodes that have been acquired as part of the QCS National Quantum Hub. Primary support will come from Prof. Simon Benjamin (Oxford) and the host group includes 14 individuals working in related areas including 4 postdocs and research fellows associated with the group.