Quantum technologies (QT) are new, disruptive information technologies that can outperform their conventional counterparts, in communications, sensing, imaging and computing. The UK has already invested significantly in a national programme for QT, to develop and exploit these technologies, and is now investing further to stimulate new UK industry and generate a supply of appropriately skilled technologists across the range of QT sectors. All QT exploit the various quantum properties of light or matter in some way. Our work is in the communications sector, and is based on the fundamental effect that measuring or detecting quantum light signals irreversibly disturbs them. This effect is built into Nature, and will not go away even when technologies (quantum or conventional) are improved in the future. The fundamental disturbance of transmitted quantum light signals enables secure communications, as folk intercepting signals when they are not supposed to (so-called eavesdroppers) will always get caught. This means Alice and Bob can use quantum light signals to set up secure shared data, or keys, which they can then use for a range of secure communications and transactions - this is quantum key distribution (QKD). The irreversible disturbance of light can also be used to generate random numbers - another very important ingredient for secure communications, cryptology, simulation and modelling. In the modern world where communications are so ubiquitous and important, there is increasing demand for new secure methods. Technologies and methods widely used today will be vulnerable to emergent quantum computing technologies, so encrypted information being sent around today which has a long security shelf-life will be at risk in the future. New "quantum safe" methods that are not vulnerable to any future QT have to be developed. So QKD and new mathematical encryption must be made practical and cost effective, and soon. The grand vision of the Quantum Communications Hub is therefore to pursue quantum communications at all distance scales, to offer a range of applications and services and the potential for integration with existing infrastructure. Very short distance communications require free space connections for flexibility. Examples include between a phone or other handheld device and a terminal, or between numerous devices and a fixed receiver in a room. The Hub will be engineering these "many-to-one" technologies to enhance practicality and real-world operation. Longer distance conventional communications - at city, metropolitan and inter-city scales - already use optical fibres, and quantum communications have to leverage and complement this. The Hub has already established the UK's first quantum network, the UKQN. We will be extending and enhancing the UKQN, adding function and capability, and introducing new QKD technologies - using quantum light analogous to that used in conventional communications, or using entanglement working towards even longer distance fibre communications. The very longest distance communications - intercontinental and across oceans - require satellites. The Hub will therefore work on a new programme developing ground to satellite QKD links. Commercial QKD technologies for all distance scales will require miniaturisation, for size, weight and power savings, and to enable mass manufacture. The Hub will therefore address key engineering for on-chip operation and integration. Although widely applicable, key-sharing does not provide a solution for all secure communication scenarios. The Hub will therefore research other new quantum protocols, and the incorporation of QKD into wider security solutions. Given the changing landscape worldwide, it is becoming increasingly important for the UK to establish national capability, both in quantum communication technologies and their key components such as light sources and detectors. The Hub has assembled an excellent team to deliver this capability.

Quantum Technology is based on quantum phenomena that govern physics on an atomic scale, enabling key breakthroughs that enhance the performance of classical devices and allow for entirely new applications in communications technology, imaging and sensing, and computation. Quantum networks will provide secure communication on a global scale, quantum sensors will revolutionise measurements in fields such as geology and biomedical imaging, and quantum computers will efficiently solve problems that are intractable even on the best future supercomputers. The economic and societal benefit will be decisive, impacting a wide range of industries and markets, including engineering, medicine, finance, defence, aerospace, energy and transport. Consequently, Quantum Technologies are being prioritised worldwide through large-scale national or trans-national initiatives, and a healthy national industrial Quantum Technology ecosystem has emerged including supply chain, business start-ups, and commercial end users. Our Centre for Doctoral Training in Applied Quantum Technologies (CDT-AQT) will address the national need to train cohorts of future quantum scientists and engineers for this emerging industry. The training program is a partnership between the Universities of Strathclyde, Glasgow and Heriot-Watt. In collaboration with more than 30 UK industry partners, CDT-AQT will offer advanced training in broad aspects of Quantum Technology, from technical underpinnings to applications in the three key areas of Quantum Measurement and Sensing, Quantum Computing and Simulation, and Quantum Communications. Our programme is designed to create a diverse community of responsible future leaders who will tackle scientific and engineering challenges in the emerging industrial landscape, bring innovative ideas to market, and work towards securing the UK's competitiveness in one of the most advanced and promising areas of the high-tech industry. The quality of our training provision is ensured by our supervisors' world-class research backgrounds, well-resourced research environments at the host institutions, and access to national strategic facilities. Industry engagement in co-creation and co-supervision is seen as crucial in equipping our students with the transferable skills needed to translate fundamental quantum physics into practical quantum technologies for research, industry, and society. To benefit the wider community immediately, we will make Quantum Technologies accessible to the general public through dedicated outreach activities, in which our students will showcase their research and exhibit at University Open Days, schools, science centres and science festivals.

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.

Single-photon counting - the ability to faithfully capture the single quantum of light - is a critical capability for a wide range of new low-light sensing applications and a host of emerging photonic quantum technologies. This proposed Programme Grant aims to significantly expand the operational region of single-photon detectors well beyond silicon's 1000nm wavelength limit into the short-wave infrared (SWIR) region of wavelengths between 1400nm to 3000nm, and part of the mid-wave infrared (MWIR) region between 3000nm and 5000nm. By scaling up SWIR and MWIR semiconductor and superconductor single-photon detectors to large area focal plane arrays, we will produce revolutionary new cameras with picosecond timing resolution which can be used, for example, to see though fog in automotive lidar scenarios, as well as allowing imaging and sensing in new applications in environmental monitoring, healthcare, and security and defence. The project will involve the design and fabrication of innovative new detector platforms of Ge-on-Si and III-V semiconductor detectors. The detectors are capable of single-photon sensitivity in the SWIR and MWIR regions, and will be fabricated in detector array format. We will also examine superconducting nanowires to expand their operation into the MWIR regions and fabricate arrayed detector configurations. A key part of the project is to integrate these arrayed detector technologies with read-out circuitry capable of rapid, low latency delivery of single-photon data. In addition, we will utilise micro-optic technology to optimise detection efficiency and demonstrate multiple wavelength filtering. The cameras will be designed for use in a range of applications areas, including lidar, where the time-of-flight of the return photons can be used for the measurement of distance. In arrayed detector format, we will make cameras from which we will demonstrate three-dimensional imaging at long distance, where the sensitivity and time-resolution will enhance imaging through dense fog and other obscurants. We will demonstrate our detector technologies in quantum cryptography applications, where encryption keys can be shared between two users. By sending data encoded in single-photons it is possible for the sender and receiver to share a secure, random key known only to them. The most critical component in this form of quantum communication is the single-photon detector - we will demonstrate the use of our detectors both in optical fibre and free-space quantum key distribution scenarios. Other emerging applications in spectroscopy and biophotonics will be demonstrated.