Quantum capacity is properly defined without encodings

Journal article (1998)

Authors

Howard Barnum Hampshire College
John A. Smolin IBM Thomas J. Watson Research Centre
B.M. Terhal Universiteit van Amsterdam, Centrum Wiskunde & Informatica (CWI)
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Published Date

1998

Language

English

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Abstract

We show that no source encoding is needed in the definition of the capacity of a quantum channel for carrying quantum information. This allows us to use the coherent information maximized over all sources and block sizes, but not encodings, to bound the quantum capacity. We perform an explicit calculation of this maximum coherent information for the quantum erasure channel and apply the bound in order find the erasure channel’s capacity without relying on an unproven assumption as in an earlier paper.