Research Context: The internet has become an indispensable tool in today's society. However, data transfer over this network is fundamentally insecure. Security of data and protection against identity theft and cyber-attacks is of crucial importance for our current and future society. These security concerns are addressed with the invention of a quantum internet - a network based on encoding and transmitting information as quantum bits - as the principles of quantum physics ensure total and fundamental secure communication. Quantum networks are the missing key technology, however, a major roadblock remains to be overcome: scalability. Building quantum networks relies on generating large numbers of individual quantum objects (in this case photons - single quanta of light) and performing controlled interactions between them. However, the fragile nature of quantum objects means that successfully preparing even one happens by chance - like a coin toss. Adding more quantum objects to a network is like adding more coins to toss - the overall chance of getting all heads reduces greatly, and so a large-scale quantum network has never been achieved. I will address this crucial issue with a quantum optical memory - a device that can store and recall photons on demand enabling one to synchronise the successful "coin tosses" across the network. The overall aim is to build and exploit a high-performance light-matter quantum network. Aims/Objectives: To achieve this aim, I will utilise my expertise in quantum light-matter interactions to build an ultrafast, high-efficiency, low-noise quantum memory at wavelengths already used in the telecoms industry. I will utilise two complementary platforms with miniaturisation capability important for scale - warm alkali vapours and cryogenically cooled rare-earth ions in solids - together with quantum memory protocols that I have pioneered, to deliver a quantum memory performance at an unprecedented level. With this device, I will demonstrate a hybridised quantum light-matter interface with the storage and on-demand recall of photons ensuring that the quantum properties of the light are preserved. This demonstration forms the key technology for the basis of the network, where I will now use two quantum memories to efficiently interface and store photons from disparate quantum sources at remote locations - a two-node network. I will then scale this light-matter network to allow for the control of multiple memories and photons to enact quantum communication tasks for the first-time. Potential Applications: In the same way the invention of the transistor led to rapid advances in computation and communications, revolutionising the 20th century, quantum networks are the underpinning technology that have the potential to bring significant change and long-term social-economic impact in the 21st century. A high-performance light-matter quantum network will bring inherently secure communication, more accurate global clock synchronization for enhanced GPS accuracy, and could even allow extending the baselines of telescopes for improved observations. Networks of quantum objects can form quantum computers that are powerful enough to solve problems that current computers cannot, with the potential to impact methods of research in the healthcare, pharmaceutical and green energy sectors. Efficient simulation and optimised computation using quantum networks could provide benefits in epidemiology and genetic research, cut costs in medication design to treat new diseases, and help improve artificial light-harvesting devices for alternative energy sources, with many more useful applications likely to be discovered in the coming decades. In the shorter term, my project will aid in training the next generation of quantum scientists and generate valuable IP to be exploited by spinout companies, further forwarding the emergent quantum technologies industry in the UK.

The primary objective of the QC2 CDT is to train the upcoming generation of pioneering researchers, entrepreneurs, and business leaders who will contribute to positioning the UK as a global leader in the quantum-enabled economy by 2033. The UK government and industry have demonstrated their commitment by investing £1 billion in the National Quantum Technologies Programme (NQTP) since 2014. In its March 2023 National Quantum Strategy document, the UK government reaffirmed its dedication to quantum technologies, pledging £2.5 billion in funding over the next decade. This commitment includes the establishment of the UKRI National Quantum Computing Centre (NQCC). The fields of quantum computation and quantum communications are at a pivotal juncture, as the next decade will determine whether the long-anticipated technological advancements can be realized in practical, commercially-viable applications. With a wide-ranging spectrum of research group activities at UCL, the QC2 CDT is uniquely situated to offer comprehensive training across all levels of the quantum computation and quantum communications system stacks. This encompasses advanced algorithms and quantum error-correcting codes, the full range of qubit hardware platforms, quantum communications, quantum network architectures, and quantum simulation. The QC2 CDT has been co-developed through a partnership between UCL and a network of UK and international partners. This network encompasses major global technology giants such as IBM, Amazon Web Services and Toshiba, as well as leading suppliers of quantum engineering systems like Keysight, Bluefors, Oxford Instruments and Zurich Instruments. We also have end-users of quantum technologies, including BT, Thales, NPL, and NQCC, in addition to a diverse group of UK and international SMEs operating in both quantum hardware (IQM, NuQuantum, Quantum Motion, SeeQC, Pasqal, Oxford Ionics, Universal Quantum, Oxford Quantum Circuits and Quandela) and quantum software (Quantinuum, Phase Craft and River Lane). Our partners will deliver key components of the training programme. Notably, BT will deliver training in quantum comms theory and experiments, IBM will teach quantum programming, and Quantum Motion will lead a training experiment on semiconductor qubits. Furthermore, 17 of our partners will co-sponsor and co-supervise PhD projects in collaboration with UCL academics, ensuring a strong alignment between the research outcomes of the CDT and the critical research objectives of the UK quantum economy. In total the cash and in-kind contributions from our partners exceed £9.1 million, including £2.944 million cash contribution to support 46 co-sponsored PhD studentships. QC2 will provide an extensive cohort-based training programme. Our students will specialize in advanced research topics while maintaining awareness of the overarching system requirements for these technologies. Central to this programme is its commitment to interdisciplinary collaboration, which is evident in the composition of the leadership and supervisory team. This team draws expertise from various UCL departments, including Chemistry, Electronics and Electrical Engineering, Computer Science, and Physics, as well as the London Centre for Nanotechnology (LCN). QC2 will deliver transferable skills training to its students, including written and oral presentation skills, fostering an entrepreneurial mindset, and imparting techniques to maximize the impact of research outcomes. Additionally, the programme is committed to taking into consideration the broader societal implications of the research. This is achieved by promoting best practices in responsible innovation, diversity and inclusion, and environmental impact.

Quantum technology will revolutionise many aspects of life and bring enormous benefits to the economy and society. The Centre for Doctoral Training in Quantum Informatics (QI CDT) will provide advanced training in the structure, behaviour, and interaction of quantum hardware, software, and applications. The training programme spans computer sciences, mathematics, physics, and engineering, and will enable the use of quantum technology in a way that is integrable, interoperable, and impactful, rather than developing the hardware itself. The training programme targets three research challenges with a strong focus on end user impact: (i) quantum service architecture concerns how to design quantum networks and devices most usefully; (ii) scalable quantum software is about feasible application at scale of quantum technology and its integration with other software; and (iii) quantum application analysis investigates how quantum technology can be used most advantageously to solve end user problems. The QI CDT will offer 75+ PhD students an intensive 4-year training and research programme that equips them with the skills needed to tackle the research challenges of quantum informatics. This new generation will be able to integrate quantum hardware with high-performance computing, design effective quantum software, and apply this in a societally meaningful way. The QI CDT brings together a coalition with national reach including over 65 academic experts in quantum informatics from five universities - the University of Edinburgh, the University of Oxford, University College London, Heriot-Watt University, and the University of Strathclyde - and three public sector partners - the National Quantum Computing Centre, the National Physical Laboratory, and the Hartree Centre. A network of over 30 industry partners, diverse in size and domain expertise, and 9 leading international universities, give students the best basis for meaningful and collaborative research. A strong focus on cohort-based training will make QI CDT students into a diverse network of future leaders in Quantum Informatics in the UK.

o achieve this vision, we will address major global research challenges towards the establishment of the "quantum internet" —?globally interlinked quantum networks which connect quantum nodes via quantum channels co-existing with classical telecom networks. These research challenges include: low-noise quantum memories with long storage time; connecting quantum processors at all distance scales; long-haul and high-rate quantum communication links; large-scale entanglement networks with agile routing capabilities compatible with - and embedded in - classical telecommunicatons networks; cost-effective scalability, standardisation, verification and certification. By delivering technologies and techniques to our industrial innovation partners, the IQN Hub will enable UK academia, national laboratories, industry, and end-users to be at the forefront of the quantum networking revolution. The Hub will utilise experience in the use of photonic entanglement for quantum key distribution (QKD) alongside state-of-the art quantum memory research from existing EPSRC Quantum Technology Hubs and other projects to form a formidable consortium tackling the identified challenges. We will research critical component technology, which will underpin the future national supply chain, and we will make steps towards global QKD and the intercontinental distribution of entanglement via satellites. This will utilise the Hub Network's in-orbit demonstrator due to be launched in late 2024, as well as collaboration with upcoming international missions. With the National Quantum Computing Centre (NQCC), we will explore applications towards quantum advantage demonstrations such as secure access to the quantum cloud, achievable only through entanglement networks. Hub partner National Physical Laboratory (NPL) working with our academic partners and the National Cyber Security Centre (NCSC) will ensure that our efforts are compatible with emerging quantum regulatory standards and post-quantum cybersecurity to bolster national security. We will foster synergies with competing international efforts through healthy exchange with our global partners. The Hub's strong industrial partner base will facilitate knowledge exchange and new venture creation. Achieving the IQN Hub's vision will provide a secure distributed and entanglement-enabled quantum communication infrastructure for UK end-users. Industry, government stakeholders and the public will be able to secure data in transit, in storage and in computation, exploiting unique quantum resources and functionalities. We will use a hybrid approach with existing classical cyber-security standards, including novel emerging post-quantum algorithms as well as hardware security modules. We will showcase our ambition with target use-cases that have emerged as barriers for industry, after years of investigation within the current EPSRC QT Hubs as well as other international efforts. These barriers include security and integrity of: (1) device authentication, identification, attestation, verification; (2) distributed and cloud computing; (3) detection, measurement, sensing, synchronisation. We will demonstrate novel applications as well as identify novel figures of merit (such as resilience, accuracy, sustainability, communication complexity, cost, integrity, etc.) beyond security enhancement alone to ensure the national quantum entanglement network can be fully exploited by our stakeholders and our technology can be rapidly translated into a commercial setting.

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.