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QI: Fachverband Quanteninformation

QI 3: Quantum Communication

QI 3.13: Vortrag

Montag, 18. März 2024, 12:45–13:00, HFT-TA 441

Bounds on Conference Key Agreement in LOSR-Networks — •Justus Neumann, Giacomo Carrara, Anton Trushechkin, Hermann Kampermann, and Dagmar Bruß — Heinrich Heine Universität, Düsseldorf, Deutschland

Conference key agreement is the extension of quantum key distribution from two to arbitrary many participants. Typically, the parties need to prepare multipartite entangled states to establish a secret key. However, generating highly multipartite entangled quantum states can be challenging in practice. We consider networks with bipartite sources, where each party is allowed to perform local operations. In addition, all parties share a classical random variable indicating the operation the parties have to perform. In this scenario the parties are not allowed to communicate classically during the prepare and measure phase. Although this limits the parties' abilities to generate a high key rate, it has advantages for practical implementations because no memories are needed. We discuss how such networks can be used to establish a secret bit string shared by all parties. Through inflation techniques, we derive upper bounds on the asymptotic multipartite key rate and we show that in a BB84- multipartite protocol the states that can be prepared in these networks do not outperform biseparable states.

Keywords: Quantum key distribution; Conference key agreement; LOSR-network; Key rate