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Disputation Frederik Hahn

26.06.2023 | 16:30
Thema der Dissertation:
Quantum Networks
Abstract: This thesis explores the potential of entangled quantum states for advanced communication, moving from conventional bipartite settings to a network of multipartite entangled states. We begin by discussing preliminary mathematics and by introducing bipartite quantum communication protocols, such as quantum teleportation, quantum repeaters, and quantum key distribution for cryptography.
Moving on to quantum networks and multipartite communication, we use quantum graph states as a theoretical tool to explore the potential of real-world quantum networks. We explain how these graph states —multipartite entangled states of quantum particles that can be manipulated with local operations— can carry quantum information and entangle particles that have never physically interacted. We consider the possibilities and limitations of entanglement manipulation, and find that certain bottleneck communication problems cannot be solved in a large class of nearest-neighbour network topologies.
Further investigating graph state entanglement, we derive new invariants of graph states and study the class of circle graph states. Finally, we consider multipartite quantum cryptography protocols with anonymity. Exploiting the rich properties of graph state entanglement, we present the first protocol for anonymous quantum conference key agreement, which could contribute to a future quantum internet.

Zeit & Ort

26.06.2023 | 16:30

Hörsaal A
Fachbereich Physik, Arnimallee 14, 14195 Berlin