For many years, quantum mechanics has been a curiosity at the heart of physics. Its development was essential to many of the key breakthroughs of 20th century science, but it is famous for counter-intuitive features; the superposition illustrated by Schrödinger's cat; and the quantum entanglement responsible for Einstein's "spooky action at a distance". Quantum Technologies are based on the idea that the "weirdness" of quantum mechanics also presents a technological opportunity. Since quantum mechanical systems behave in a fundamentally different way to large-scale systems, if this behaviour could be controlled and exploited it could be utilised for fundamentally new technologies. Ideas for using quantum effects to enhancing computation, cryptography and sensing emerged in the 1980s, but the level of technology required to exploit them was out of reach. Quantum effects were only observed in systems at either very tiny scales (at the level of atoms and molecules) or very cold temperatures (a fraction of a degree above absolute zero). Many of the key quantum mechanical effects predicted many years ago were only confirmed in the laboratory in the 21st century. For example, a decisive demonstration of Einstein's spooky action at a distance was first achieved in 2015. With such rapid experimental progress in the last decade, we have reached a turning point, and quantum effects previously confined to university laboratories are now being demonstrated in commercially fabricated chips and devices. Quantum Technologies could have a profound impact on our economy and society; Quantum computers that can perform computations beyond the capabilities of the most powerful supercomputer; microscopic sensing devices with unprecedented sensitivity; communications whose security is guaranteed by the laws of physics. These technologies could be hugely transformative, with potential impacts in health-care, finance, defence, aerospace, energy and transport. While the past 30 years of quantum technology research have been largely confined to universities, the delivery of practical quantum technologies over the next 5-10 years will be defined by achievements in industrial labs and industry-academic partnerships. For this industry to develop, it will be essential that there is a workforce who can lead it. This workforce requires skills that no previous industry has utilised, combining a deep understanding of the quantum physics underlying the technologies as well as the engineering, computer science and transferrable skills to exploit them. The aim of our Centre for Doctoral Training is to train the leaders of this new industry. They will be taught advanced technical topics in physics, engineering, and computer science, alongside essential broader skills in communication and entrepreneurship. They will undertake world-class original research leading to a PhD. Throughout their studies they will be trained by, and collaborate with a network of partner organisations including world-leading companies and important national government laboratories. The graduates of our Centre for Doctoral Training will be quantum technologists, helping to create and develop this potentially revolutionary 21st-century industry in the UK.

Quantum computation has just entered a new era, that of Noisy Intermediate-Scale Quantum (NISQ) technologies in which quantum processors are able to perform calculations beyond the capabilities of the world's greatest supercomputers. This remarkable achievement sets an important milestone in quantum computing (QC) and brings focus towards the ultimate goal of the QC roadmap: building a fault-tolerant quantum machine. A machine with sufficient error-free computing resources to run quantum algorithms with the potential to radically transform society. Algorithms that will help us better forecast weather and financial markets, speed up searches in unsorted databases, essential for the Big Data era, and most importantly, accelerate the pace of discovery of new materials and medicines, so relevant for the times we live in. The most promising routes to fault-tolerant QC will require quantum error correction (QEC) to enable accurate computing despite the intrinsically noisy nature of the individual quantum bits constituting the machine. The idea is based on distributing the logical information over a number of physical qubits. As long as the physical qubits satisfy a maximum error rate (1% for the most forgiving method, the surface code) fault-tolerance can be achieved. The exact physical qubit overhead (per logical qubit) depends on the error rate but considering state-of-the-art qubit fidelities, it will likely be a figure in excess of a hundred. QEC is then expected to take the number of required physical qubits to many thousands for economically significant algorithms and to many millions for some of the more demanding quantum computing applications. Scaling is hence a generic scientific and technological challenge. Building qubits based on the spin degree of freedom of individual electrons in silicon nanodevices offers numerous advantages over competing technologies such as the scalability of the most compact solid-state approach and the extensive industrial infrastructure of silicon transistor technology devoted to fabricating multi-billion-element integrated circuits. Besides, silicon electron spin qubits are one of the most coherent systems in nature, characteristic that has enabled demonstrating all the operational steps - initialization, control and readout - with sufficient level of precision for fault-tolerant computing. However, most of the results achieved so far come from devices fabricated in academic cleanrooms with relatively low level of reproducibility and in one- or two-qubit processors at best [Huang et al. Nature 569, 532]. But the recent demonstration of a single hole spin qubit [Maurand et al Nat Commun 7 13575] and electron spin control and readout in devices fabricated in a 300 mm complementary metal-oxide-semiconductor (CMOS) platform open an opportunity to trigger a transition from lab-based proof-of-principle experiments to manufacturing qubits at scale [Gonzalez-Zalba et al, Physics World (2019)]. In the project SiFT, I will build on my pioneering work on CMOS-based quantum computing [Nat Commun 6 6084, Nat Elect 2 236, Nat Nano 14 437] to demonstrate, for the first time, all the necessary steps to run the surface code. I will target a two-dimensional qubit lattices where arbitrary quantum errors could be detected and corrected making clusters of qubits more reliable that the individual constituents. My quantum circuit designs will be manufactured in experimental and commercial silicon foundries that use very large-scale integration processes. The project will be the steppingstone towards building in the UK a large-scale silicon-based quantum processor with sufficient error-free computational resources to make an impact on society. It will help take QC beyond NISQ into the fault-tolerant era where the computational promises of QC can be fully exploited.

The EPSRC Quantum Computing and Simulation Hub will enable the UK to be internationally leading in Quantum Computing and Simulation. It will drive progress toward practical quantum computers and usher in the era where they will have revolutionary impact on real-world challenges in a range of multidisciplinary themes including discovery of novel drugs and new materials, through to quantum-enhanced machine learning, information security and even carbon reduction through optimised resource usage. The Hub will bring together leading quantum research teams across 17 universities, into a collaboration with more than 25 national and international commercial, governmental and academic entities. It will address critical research challenges, and work with partners to accelerate the development of quantum computing in the UK. It will foster a generation of UK-based scientists and engineers equipped with the new skill sets needed to make the UK into a global centre for innovation as the quantum sector emerges. The Hub will engage with government and citizens so that there is a wide appreciation of the potential of this transformative technology, and a broad understanding of the issues in its adoption. Hub research will focus on the hardware and software that will be needed for future quantum computers and simulators. In hardware we will advance a range of different platforms, encompassing simulation, near term quantum computers, and longer term fully scalable machines. In software the Hub will develop fundamental techniques, algorithms, new applications and means to verify the correct operation of any future machine. Hardware and software research will be closely integrated in order to provide a full-stack capability for future machines, enabled by the broad expertise of our partners. We will also study the architecture of these machines, and develop emulation techniques to accelerate their development. Success will require close engagement with a wide range of commercial and government organisations. Our initial partners include finance (OSI), suppliers (Gooch & Housego, Oxford Instruments, E6), integrators and developers (OQC, QM, CQC, QxBranch, D-Wave), users from industry (Rolls-Royce, Johnson Matthey, GSK, BT, BP, TrakM8, Airbus, QinetiQ) and government (DSTL, NCSC), and other research institutions (NPL, ATI, Heilbronn, Fraunhofer). We will build on this strong network using Industry Days, Hackathons and targeted workshops, authoritative reports, and collaborative projects funded through the Hub and partners. Communications and engagement with the community through a range of outreach events across the partnership will inform wider society of the potential for quantum computing, and we will interact with policy makers within government to ensure that the potential benefits to the UK can be realised. The Hub will train researchers and PhD students in a wide range of skills, including entrepreneurship, intellectual property and commercialisation. This will help deliver the skilled workforce that will be required for the emerging quantum economy. We will work with our partners to deliver specific training for industry, targeting technical, commercial and executive audiences, to ensure the results of the Hub and their commercial and scientific opportunities are understood. The Hub will deliver demonstrations, new algorithms and techniques, spinout technologies, and contribute to a skilled workforce. It will also engage with potential users, the forthcoming National Centre for Quantum Computing, the global QC community, policy makers and the wider public to ensure the UK is a leader in this transformative new capability.