Technological advances have led to the availability of electronic devices like laptops, mobile devices and global positioning systems. In order to increase performance, modern technology has followed the path of miniaturising the components to reduce the overall size of commercial devices. Following this trend, we have now reached the point where matter can be controlled at the smallest scale: the single atom. It is in this new realm of physics that unconventional effects take place: when we deal with structures composed of just a few atoms or when we manipulate single electronic charges, the physics follows rules described by quantum mechanics. A completely new range of effects take place and devices with novel functionalities can be created: the quantum information revolution seems to be within reach. A very exciting research field focuses on the study of nanostructures, entities whose dimensions are of the order of 0.000000001m. Such small structures can be used for controlling single particles of light: single photons. Conventional light sources emit a large number of photons in a wide angular range and are mainly used for lighting and imaging. The ability to control light at the single-photon level is technologically challenging but tremendously interesting. If we can store information encoded on single photons, we can transfer it at the speed of light with a guaranteed secure communication. Single-photon emitters also find applications in imaging and medical sensing. Unfortunately, many single-photon sources operate at very low temperatures, which require the use of liquid helium, which is expensive and inconvenient for real-world applications. A material called Gallium Nitride (GaN) offers opportunities to overcome these limitations. GaN is a semiconductor crystal, and defects in that crystal can act as single-photon emitters, as can indium gallium nitride (InGaN) nanostructures embedded in a GaN matrix. Such nanostructures can emit single photons at room temperature, across a very wide range of wavelengths. However, incorporating these emitters into practical devices is very challenging. They tend to form at random locations in the crystal, which makes it hard to ensure that a device contains an optimally-positioned single emitter and that the light is emitted in the desired direction with high efficiency, as required for applications. In this project, we will develop technologies which allow us to control where an emitter forms, and integrate those site-controlled emitters with structures which extract the light from the device efficiently and channel it in a desired direction. We will create devices where the light extraction structures are integrated with the electrical injection of charge carriers into the emitter. That means that we will be able to use an applied voltage to either drive the single-photon emission or to alter the wavelength (or colour) of the emitted photon. The approach we will take to improving light extraction uses technologies that are easily incorporated into a standard manufacturing routine. We will put mirror-like structures underneath the single-photon emitters; above them, on the crystal surface, we will place tiny rings of metal, which can act like a lens, directing the light into the application system. In addition to being relatively easy to manufacture, relative to other possible technologies, this approach has additional advantages: it avoids etching the GaN crystal, which can damage device performance, and it also places less stringent requirements on achieving a very specific wavelength from the single-photon emitter. The metallic ring also doubles up as a contact for electrical injection. Overall, this provides a scalable, robust route to creating a new quantum technology - which addresses UK government priorities for advanced materials and manufacturing, and represents a crucial step forward in the implementation of quantum emitters in real-life devices.

The critical importance of capabilities for semiconductor research in the UK is recognised as part of a national strategy, as stressed in the recent BEIS Report 'The semiconductor industry in the UK'. Particular strength in research is centred around a number of cleanroom facilities located at academic institutuions. The University of Southampton hosts a range of cutting-edge nanofabrication tools which enable a range of research activities in electronic and photonic devices. Fabrication of semiconductor devices and circuits becomes cost effective when processed on a large wafer. However, process efficiency can only be achieved if an ultra-high-resolution scanning electron microscope (SEM) with material characterisation system is available to provide high throughput feedback results to improve fabrication and facilitate novel process development. Manually operated SEMs are a common imaging tool for characterisation used in academic research but automated in-line imaging of wafers throughout a process flow is required to achieve fast imaging and shorten inspection time from fabrication processes. The aim of the proposal is to acquire an ultra-high-resolution SEM (UHR-SEM) capable of material characterisation for wafers up to 200 mm in diameter at the University of Southampton. As device feature sizes are reduced, dimension and performance variations across the wafer become an issue which must be mitigated at the early stage of the fabrication. Therefore, the proposed UHR-SEM will be unique within the UK academic landscape since it will perform automated in-line imaging and analysis of entire wafers up to 200 mm in diameter at sub-nm resolution. The system will also have a low landing voltage on samples to reduce surface damage during imaging of delicate devices and patterned resists, as well as a good depth of focus for the inspection of thick multi-stack materials. The UHR-SEM will address the main challenges in large wafer imaging such as generating relevant surface metrology information at nanoscale dimensions and creating a detailed map showing various material parameters such as chemical composition and defect distribution.

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.

However, access to silicon prototyping facilities remains a challenge in the UK due to the high cost of both equipment and the cleanroom facilities that are required to house the equipment. Furthermore, there is often a disconnect in communication between industry and academia, resulting in some industrial challenges remaining unsolved, and support, training, and networking opportunities for academics to engage with commercialisation activities isn't widespread. The C-PIC host institutions comprising University of Southampton, University of Glasgow and the Science and Technologies Facilities Council (STFC), together with 105 partners at proposal stage, will overcome these challenges by uniting leading UK entrepreneurs and researchers, together with a network of support to streamline the route to commercialisation, translating a wide range of technologies from research labs into industry, underpinned by the C-PIC silicon photonics prototyping foundry. Applications will cover data centre communications; sensing for healthcare, the environment & defence; quantum technologies; artificial intelligence; LiDAR; and more. We will deliver our vision by fulfilling these objectives: Translate a wide range of silicon photonics technologies from research labs into industry, supporting the creation of new companies & jobs, and subsequently social & economic impact. Interconnect the UK silicon photonics ecosystem, acting as the front door to UK expertise, including by launching an online Knowledge Hub. Fund a broad range of Innovation projects supporting industrial-academic collaborations aimed at solving real world industry problems, with the overarching goal of demonstrating high potential solutions in a variety of application areas. Embed equality, diversity, and inclusion best practice into everything we do. Deliver the world's only open source, fully flexible silicon photonics prototyping foundry based on industry-like technology, facilitating straightforward scale-up to commercial viability. Support entrepreneurs in their journey to commercialisation by facilitating networks with venture capitalists, mentors, training, and recruitment. Represent the interests of the community at large with policy makers and the public, becoming an internationally renowned Centre able to secure overseas investment and international partners. Act as a convening body for the field in the UK, becoming a hub of skills, knowledge, and networking opportunities, with regular events aimed at ensuring possibilities for advancing the field and delivering impact are fully exploited. Increase the number of skilled staff working in impact generating roles in the field of silicon photonics via a range of training events and company growth, whilst routinely seeking additional funding to expand training offerings.

Silicon photonics is the manipulation of light (photons) in silicon-based substrates, analogous to electronics, which is the manipulation of electrons. The development cycle of a silicon photonics device consists of three stages: design, fabrication, and characterisation. Whilst design and characterisation can readily be done by research groups around the country, the fabrication of silicon photonics devices, circuits and systems requires large scale investments and capital equipment such as cleanrooms, lithography, etching equipment etc. Based at the Universities of Southampton and Glasgow, CORNERSTONE 2.5 will provide world-leading fabrication capability to silicon photonics researchers and the wider science community. Whilst silicon photonics is the focus of CORNERSTONE 2.5, it will also support other technologies that utilise similar fabrication processes, such as MEMS or microfluidics, and the integration of light sources with silicon photonics integrated circuits, as well as supporting any research area that requires high-resolution lithography. The new specialised capabilities available to researchers to support emerging applications in silicon photonics are: 1) quantum photonics based on silicon-on-insulator (SOI) wafers; 2) programmable photonics; 3) all-silicon photodetection; 4) high efficiency grating couplers for low energy, power sensitive systems; 5) enhanced sensing platforms; and 6) light source integration to the silicon nitride platform. Access will be facilitated via a multi-project-wafer (MPW) mechanism whereby multiple users' designs will be fabricated in parallel on the same wafer. This is enabled by the 8" wafer-scale processing capability centred around a deep-UV projection lithography scanner installed at the University of Southampton. The value of CORNERSTONE 2.5 to researchers who wish to use it is enhanced by a network of supporting companies, each providing significant expertise and added value to users. Supporting companies include process-design-kit (PDK) software specialists (Luceda Photonics), reticle suppliers (Compugraphics, Photronics), packaging facilities (Tyndall National Institute, Bay Photonics, Alter Technologies), a mass production silicon photonics foundry (CompoundTek), an epitaxy partner for germanium-on-silicon growth (IQE), fabrication processing support (Oxford Instruments), an MPW broker (EUROPRACTICE), a III-V die supplier (Sivers Semiconductors) and promotion and outreach partners (Photonics Leadership Group, EPIC, CSA Catapult, CPI, Anchored In). Access to the new capabilities will be free-of-charge to UK academics in months 13-18 of the project, and 75% subsidised by the grant in months 19-24. During the 2-year project, we will also canvas UK demand for the capability to continue to operate as an EPSRC National Research Facility, and if so, to establish a Statement of Need.