Quantum Network Steering

Over the last decade, quantum networks have grown as one of the top candidates to greatly enhance secure processing, communication and computation of information. They exploit entanglement (distributed by photons) to establish correlations between distant systems that are stronger than possible with classical physics. These strong quantum correlations can boost technologies beyond classical limits: they provide a quantum advantage. However, common theoretical approaches to quantum networks suffer from the trade-off between quantum advantages, experimental demands, and security. A first approach is to fully-trust the implementation of network devices, i.e., to assume no defects or malicious behaviour. While optimally providing quantum advantages, this approach is vulnerable to malfunctioning or unnoticed hacking, rendering it insecure for applications. The second approach fully-distrusts the devices and assumes they are subjected to hacking attacks. While providing the highest-level of security, this approach is currently too demanding to practically implement it, rendering it unrealistic for near-term technologies. QNETS will overcome this challenge through the concept of quantum steering. In a steering approach, the network is composed of both, fully-trusted and fully-distrusted devices. It assigns a level of trust to each device individually depending on its role in the network, allowing for implementations of quantum networks under more realistic security assumptions using near-term technologies. In an inter-disciplinary effort, QNETS combines techniques from quantum information, applied mathematics, and computer science. In particular, QNETS will (1) lay out the theoretical foundation of quantum network steering (2) develop mathematical tools for its characterization, and (3) design protocols for its real-world applications, such as cryptography. Upon completion, QNETS will pave the way for the long-term goal of a quantum internet for information processing.