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Information Processing in Future Quantum Networks

Periodic Reporting for period 1 - IPQNet (Information Processing in Future Quantum Networks)

Reporting period: 2019-05-01 to 2021-04-30

This research project examined how to process information on a quantum network, from establishing necessary quantum states between nodes, to routing information along the underlying architecture and finally running multipartite cryptographic protocols. These issues are imperative in modern society, due to the huge investments from private and public institutions, on quantum technologies. Since the advancements in quantum implementations are starting to show, it is important to close the gap between theoretical and experimental approaches. The aim of this project was therefore to exploit the technological advancements to the fullest, in order to provide some gains for secure communication. This will eventually lead us to a more secure society and a better understanding of the new technologies and their potential. The specific objectives of the project were the following:
1) to provide verification techniques for quantum resources. These would extend and generalise previous research on specific types of quantum states, to more general settings.
2) to study routing of quantum resources on networks, in order to obtain and share the necessary quantum states in specific network topologies.
3) to examine the composability of quantum and classical routines in security frameworks that are modular and allow for parallel and sequential composition without compromising security.
This project lasted 8 months in total.
One publiication that resulted from the work done in this period , 'Quantum network routing and local complementation: Frederik Hahn, Anna Pappa and Jens Eisert, NPJ Quantum Information 5​, 76 (2019).'. In this work, we explore different approaches of routing quantum information over a network, by using graph theoretic results and local quantum operations. One other work is also underway, that tries to impement some of the methods proposed in the paper above, using remote quantum servers.

There are also some preliminary results on verification of quantum resources, extending previous research to graph states, and specifically on what is called 'Absolutely Maximally Entangled' states (AME), which have specific types of symmetries. Lack of symmetries in general graph states prohibited a straight-forward generalisation of the techniques that I was planning to use, therefore I have decided to concentrate as a starting point, to states that show some different type of symmetry, and that have not been studied before in such an adversarial verification setting.

Regarding composability, during my stay at Caltech university, I have formed a collaboration with the Quantum Group there, and we are at this point working on extending settings of multiparty delegated computation, to achieving more general adversarial scenarios that are composably secure. This work is still ongoing.

For the duration of the project, I have also coordinated the submission of a review on Quantum Electronic voting, which got substantially extended to include the first formal definitions of security. This work is submitted to the journal AMC TQC.
As mentioned above, several results have come out of this project:
1) A new way of routing quantum information over networks,
2) The idea to address first specific types of symmetric quantum states, before trying to extend to any general graph state
3) A new collaboration that will target delegated quantum computation
4) The first definitions of security in quantum electronic voting
Example of quantum routing using graph states