Final Report Summary - QCC (Quantum Communication and Cryptography) Quantum Technologies have shown the potential to revolutionize the future of information technologies. The long-term vision of this project is a network of quantum and classical devices, where individual agents have the ability to communicate efficiently in a variety of ways with trusted and untrusted parties and securely delegate computational tasks to a number of untrusted large-scale quantum computing servers. In such an interconnected world, the notion of security against malicious quantum adversaries is an imperative. In addition, it is necessary that the interaction between agents remains efficient and, in order to guarantee the viability of the network, it is important to provide the agents with incentives for honest behaviour.The Quantum Communications and Cryptography project made considerable steps towards the realization of such a complex network of classical and quantum communication by providing a solid theoretical foundation that nevertheless is able to foresee and handle the intricacies of real-life implementations. We set the benchmark, both theoretically as well as experimentally, of some necessary communication components for such a hybrid network. The concrete results of our project are: design of novel cryptographic primitives as a powerful toolkit for the quantum network infrastructure; novel quantum games that showcase the power of quantum information to enhance the benefits of honest behaviour; important lower bounds for the compression of classical interactive communication through techniques from quantum nonlocality; use of state-of-the-art photonic systems in order to implement complex cryptographic primitives, such as coin flipping, verification of multipartite entanglement and quantum money schemes.Our project has showcased the potential power of the quantum internet, which has now emerged as a main objective of the European effort on quantum communication technologies.
