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Paper Detail

Paper IDQ.7.4
Paper Title Additivity in Classical-Quantum Wiretap Channels
Authors Arkin Tikku, School of Physics, University of Sydney, Australia; Joseph M. Renes, ETH Zürich, Switzerland; Mario Berta, Imperial College London, United Kingdom
Session Q.7: Quantum Security
Presentation Lecture
Track Quantum Systems, Codes, and Information
Manuscript  Click here to download the manuscript
Virtual Presentation  Click here to watch in the Virtual Symposium
Abstract Due to Csiszár and Körner, the capacity of classical wiretap channels has a single-letter characterisation in terms of the private information. For quantum wiretap channels, however, it is known that regularisation of the private information is necessary to reach the capacity. Here we study hybrid classical-quantum wiretap channels in order to resolve how much quantumness is needed to witness non-additivity phenomena in Shannon information theory. For wiretap channels with quantum inputs but classical outputs, we prove that the characterisation of the capacity in terms of the private information stays single-letter. Hence, entangled input states are of no asymptotic advantage in this setting. For wiretap channels with classical inputs, we show by means of explicit examples that the private information already becomes non-additive when either one of the two receivers becomes quantum (with the other receiver staying classical). This gives non-additivity examples that are not caused by entanglement and illustrates that in the wiretap model quantum adversaries are strictly different from classical adversaries.

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2021 IEEE International Symposium on Information Theory

11-16 July 2021 | Melbourne, Victoria, Australia

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