SAMOP 2023 – scientific programme

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QI: Fachverband Quanteninformation

QI 6: Poster I (joint session QI/Q)

QI 6.10: Poster

Monday, March 6, 2023, 16:30–19:00, Empore Lichthof

Quantum Key Distribution from Bound Entanglement — •Zeynab Tavakoli¹ and Gláucia Murta² — ¹Institut für Theoretische Physik, Universität zu Köln, Zülpicher Str. 77, D-50937 Köln, Germany — ²Institut für Theoretische Physik III, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany

Quantum key distribution (QKD) aims to secure communication and establish a secret key between two honest parties. A secret key is a string of independent and random bits known to both parties. Key distillation in QKD is related to entanglement distillation; by distilling a maximally entangled state, one can get the key by measuring it. The belief was that achieving security is equivalent to distilling maximally entangled states. However, Authors of [Phys.Rev.Lett.80,5239,(2005)] show bound entangled states are usable to obtain key. Bound entangled states are quantum states that no maximally entangled states can be distilled from them using LOCC. Bound entangled states used in QKD have entanglement, which protects correlations from the environment. However, the entanglement is so twisted that it cannot be brought into a maximally entangled state. In this work, we studied known examples of bound entangled states useful for QKD. In particular, we investigate the noise tolerance of the corresponding QKD protocol, construct new bound entangled states around the original examples, and investigate their achievable key rates. Finally, we investigate if bound entangled states can be used in a simple QKD protocol where a single copy of the state is distributed and measured each round.