Applications of squeezed light span quantum technologies, including sensing, communications and computing. Integrated photonics provides scale-up, miniaturisation and increased robustness of optical devices, and various material platforms are being explored for photonic technologies that harness quantum phenomena, including squeezed light. This is due to the phase stability provided for phase sensitive quantum photonic components, such as homodyne detection. However, there is currently no approach to integrate squeezed light generation and quantum light detection into one chip. This project will engineer a scalable and manufacturable integrated photonics platform that generates, manipulates and measures squeezed quantum states of light in one monolithic chip architecture - silicon nitride nano-photonics. This will simplify assembly, miniaturise footprint, and enhance robustness of components for: quantum sensing, quantum communications and continuous variables quantum computing.

The project Software Enabling Early Quantum Advantage (SEEQA, pronounced 'seeker') is a joint effort by Oxford, UCL, and Bristol, supported by multiple UK quantum startup companies and NQCC. The aim is to make the era of "quantum advantage" arrive sooner! "Advantage" means having real working quantum computers that can perform tasks that are either impossible, or prohibitively slow or expensive, by any conventional means. We'll know this era has arrived when we can solve otherwise-infeasible tasks in areas such as chemistry and materials discovery or in solving complicated resource allocation problems with near-zero waste. Although quantum computers have long promised this kind of advantage, it has not yet been realised. There are many reasons -- partly it is just that the prototype hardware needs more time to mature. But progress needs to be made in the practical theory to support quantum computing, to 'lower the bar' that the hardware needs to be able to reach. This is what SEEQA will do, in three main themes: 1. Figuring out how best to use state-of-the-art conventional computing power to help early quantum computers. There are two main ways: First, the conventional computers can actually help run the task that the quantum computer is performing. The task gets broken up into lots of small quantum computations, and the conventional computer gets all the results and puts them together to decide what to do next. The other way a conventional computer can help is by monitoring the quantum processor for errors: there is some detective work to do in order to infer the nature of the errors from the evidence that comes from monitoring, and a conventional computer needs to do this -- it's called decoding. 2. Coming up with new ways in which to handle or suppress errors. As mentioned, quantum computers (especially the early ones) suffer from 'noise' which means little imperfections in everything that is done. If not handled, the resulting errors will lead to useless outputs. There are many ideas for fighting errors, but SEEQA will address new possibilities. In particular, SEEQA will investigate the interface between two major approaches to find new solutions: The approaches are called Quantum Error Mitigation (QEM), which suppresses error damage, and Quantum Error Correction (QEC) which can totally fix errors but is currently very expensive in terms of number of components needed. Also, SEEQA will explore and advance some of the more recent and sophisticated ideas for handling measurement errors -- if you can't trust the output of the quantum computer you are very limited! 3. Finally, SEEQA will focus on the interrelationship between the architecture or protocol we would like to perform, and the available hardware architecture (including noise sources and other imperfections, the 'topology' which means the question of which qubits can directly 'see' other qubits, and so on). Although quite a bit is known about this, there remain a great many questions within the two themes (a) "what algorithms can run well on my architecture?", and (b) "what architectures can my algorithm run on?" Underpinning all this theoretical research, it will be vital to be able to test things out. The SEEQA project will have two kinds of provision: First, very efficient software that runs on conventional computers to 'pretend' to be quantum computers - exactly simulating them using the well-known laws of quantum physics. However it will only ever be possible to work with small emulated quantum computers because the quantum state is so complex. So it is vital that SEEQA also has access to real prototype quantum processors -- and as many as possible because they are various types. Fortunately SEEQA has multiple letters of support, offering resources approaching £500k, from pioneering UK hardware companies that have working quantum prototypes right now. They will make available their experts and their devices to SEEQA in order to help us to succeed.

This project aims to use photonic quantum simulators to investigate key open questions in particle physics involving, separately, neutrinos and mesons. The project will tackle the existence of 'sterile' flavours of neutrino, how flavour oscillations are modified by neutrino interactions, and neutral B-meson oscillations (between themselves and their antiparticle) that violate CP symmetry by a greater degree than allowed by the Standard Model. Photonics is a versatile platform for simulating fermionic and anyonic statistics, and non-Hermitian Hamiltonians. Quantum photonics experiments have progressed to the point where >100 photons can be generated, coherently manipulated, and detected. Leveraging the mature fabrication capabilities of the telecoms and microelectronics industries has allowed ~1000 optical components to be co-integrated into a single photonic quantum processor. In this project we aim to use the reconfigurability afforded by photonics to map complex systems studied in particle physics into the controllable and well understood platform of quantum photonics. Such analogue quantum simulators, where there is a one-to-one mapping between the dynamics of both systems, have been shown to be a promising avenue to useful but specific quantum computation without a fault tolerant quantum computer. Bristol University hosts an esteemed group in particle physics with longstanding links to the LHCb and CERN; the university also hosts extensive and world leading expertise and infrastructure in photonic quantum technologies. This project aims to foster interdisciplinary research, bringing the benefits of quantum computing and simulation to the high energy and particle physics community. Our ambition is for new fundamental physics to be discovered by UK particle physics researchers through modelling carried out on UK quantum computing and simulation technologies.

Quantum information science and technologies (QIST) are uniquely placed to disrupt and transform sectors across the board. Quantum technologies, by exploiting the distinctive phenomena of quantum physics, can perform functions fundamentally unachievable by technologies based solely upon classical physics. For example, when applied to computing, calculations and operations that would take the best supercomputers hundreds of years to complete could be resolved within seconds using quantum computers; as another example, QIST can also be used in sensing and imaging to obtain enhanced precision in a variety of measurements ranging from gas concentrations to gravitational waves, supporting established industries in sectors like manufacturing, energy and healthcare. Furthermore, the application of quantum technologies will have significant implications within communications and security given their ability to break traditional encryption methods used to protect data within financial transactions or military communications while at the same time offering a range of novel, secure solutions largely compatible with the existing infrastructures. The potential of quantum technologies is well demonstrated through its significant financial and strategic backing globally. Restricted to academic environments up until the start of the last decade, the worldwide investment into quantum initiatives has now reached $33 billion, with significant contributions made across China, the US, and Europe. In the UK, the strategic importance of quantum technologies is clear: with a strategic commitment of £2.5 billion over the next decade, EPSRC has listed Quantum Technologies a mission-inspired research priority and the Department for Science Innovation and Technology have named quantum technologies as one of their seven technology families within the UK's Innovation Strategy. It is clear that, around the world, quantum technologies are flourishing. While the technological potential and national importance of QIST to the UK is undeniable, a key challenge to realising our ambitions in this area is the ability to develop a quantum workforce of capable physicists, engineers, computer scientists, and mathematicians with both the requisite expertise in quantum information science and expertise in the technologies that will realise it. In addition, the leaders of the UK's quantum future must possess critical professional skills: they must be excellent communicators, leaders, entrepreneurs, and project managers. To meet this key ambition and its resultant needs, the programme offered by the Quantum Information Science and Technologies Centre for Doctoral Training (QIST CDT) is uniquely positioned to deliver the diversity of skills and experience needed to supply the UK with internationally renowned QIST leaders across policy, innovation, research, entrepreneurship, and science communication. QIST CDT students will receive academic training delivered by world-recognised top educators and researchers; undertake industrially-relevant training modules co-delivered with industry partners; gain hands-on experience within world-leading quantum research laboratories; receive one-to-one entrepreneurial mentorship; undergo intellectual property and science policy training; undertake on-site industry placements; and complete multi-faceted cohort projects designed to develop multidisciplinary teamwork. This combination of world-class academic research training, which can be undertaken in a vast array of quantum-technology-relevant sectors, with bespoke instruction in professional skills driven by the needs of current and future quantum industry, will produce graduates with a drive to make a difference in Quantum Technologies and the skills to make that happen.

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.