2007/05/25 by Graeme Smith · 4 citations
Computer Science · Engineering · Physics and Astronomy · #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Wireless Communication Security Techniques #quant-ph
paper · pdf · doi:10.1103/physreva.78.022306
published as Phys. Rev. A 78, 022306 (2008) · 8 pages, 1 figure
arxiv created 2007/05/25 · openalex publication_date 2008/08/05 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/29
We study the symmetric-side-channel-assisted private capacity of a quantum channel, for which we provide a single-letter formula. This capacity is additive, convex, and, for degradable channels, equal to the unassisted private capacity. While a channel's (unassisted) capacity for private classical communication may be strictly larger than its quantum capacity, we will show that these capacities are equal for degradable channels, thus demonstrating the equivalence of privacy and quantum coherence in this context. We use these ideas to find new bounds on the key rate of quantum key distribution protocols with one-way classical post-processing. For the Bennett-Brassard 1984 protocol, our results demonstrate that collective attacks are strictly stronger than individual attacks.