Space-to-Ground Integrated Quantum Networks (SIQN)

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.