Quantum communications provides a way to guarantee security of encrypted data transmissions across networks, based on fundamental physical laws. Unlike conventional cryptography, quantum communications are immune to future advances in computing power and mathematics, making quantum communication networks an important part of keeping our most precious and private data safe in the information age. This project aims to address a missing piece of the solution, and build and demonstrate a low error quantum network node compatible with established point-to-point link quantum encryption systems. This is vital to extend the utility of dedicated links to flexible networks, and the quantum internet. Our approach will be based on development of newly emerging semiconductor telecom quantum LED technology, which shares roots with conventional opto-electronics. Our research plan will develop enhanced LED designs that will revolutionise performance, including high frequency operation. Finally, we will begin field testing of our systems, distributing quantum-entangled LED light over installed optical fibre infrastructure.

The quantum theory elaborated in the 20th century revolutionised the way we describe the world at the atomic scale. It told us that light is made up of particles (or “quanta”) called photons. Recently it has been realised that encoding information on individual photons could revolutionise current IT systems by creating properties that are otherwise impossible. For example it can allow fundamentally secure communication networks, imaging and ranging systems with resolution beyond that possible with ordinary light and ultra-powerful quantum computers. The key component for all these applications is a generator of individual photons. This project is developing sources of individual photons, as well as pairs of photons with ‘entangled’ properties. The photon source is based on a semiconductor device, similar to that found in LED lighting, traffic lights or TV remotes. As these sources can be manufactured cheaply in large numbers, it will allow us to take these exciting new quantum technologies out of the lab and into everyday life.

The quantum theory elaborated in the 20th century revolutionised the way we describe the world at the atomic scale. It told us that phenomena and measurements made on single particles can be completely unpredictable. Recently it has been realised that these effects could be very useful for generating the random numbers and secret keys that are needed in the cryptographic applications that protect IT systems and networks. This project is developing chip-based technologies for generating random numbers and keys and integrating them into demonstrator systems for secure communications. As these devices can be manufactured cheaply in large numbers, it will allow us to take these innovative new quantum technologies out of the lab and into everyday life.

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.

Data is fast becoming the underlying driver of the global economy. Securing the transmission of data as it is routed around the world is therefore of utmost importance. Today we use classical cryptography protocols, such as RSA and AES, to secure a wide range of sensitive data including financial data, health records, commercial secrets, and sensitive governmental and defence information. However, this data is at threat from attacks by quantum computers. As the resource of quantum computers grows, their ability to break traditional cryptographic protocols becomes ever more likely. Quantum cryptographic methods such as quantum key distribution (QKD) are, by nature, resistant to these attacks and they can secure our data now and into the future. A typical link between two users that is secured by QKD is serviced by fibre-optics and is limited in distance to approximately 175 km. This is because the inherent losses of fibre-optic cables means that above these distances there is too little signal to perform the QKD protocol. To overcome this limit, we can use free-space links, which can have much lower losses per unit distance. Recently, there has been a push toward performing QKD that is intermediated by satellites in low-Earth orbit. This type of satellite-to-ground QKD can break the distance limit and allow for secure communication between users separated by intercontinental distances. Current implementations of satellite QKD (SQKD) suffer from impracticalities arising from slow clock rates and the requirement of large telescopes to provide enough encryption material to service even a single ground node. In this project we will develop technology for high-rate SQKD and integrate this technology to ground networks enabling secure communication across the globe. The hardware and software developed will overcome current limitations by operating in real-time and at gigahertz (1 billion Hz) clock rates. Furthermore, software to share quantum keys between ground nodes serviced by SQKD will be developed to seamlessly secure data transfer around the world.