Showing papers by "Andreas Winter published in 1998"
TL;DR: In this article, the capacity region of classical-quantum multiway channels for transmission of classical information is derived in a uniform way, which are analogous to the classically known ones, simply replacing Shannon entropy with von Neumann entropy.
Abstract: We define classical-quantum multiway channels for transmission of classical information, after recent work by Allahverdyan and Saakian. Bounds on the capacity region are derived in a uniform way, which are analogous to the classically known ones, simply replacing Shannon entropy with von Neumann entropy. For the single receiver case (multiple access channel) the exact capacity region is determined. These results are applied to the case of noisy channels, with arbitrary input signal states. A second issue of this work is the presentation of a calculus of quantum information quantities, based on the algebraic formulation of quantum theory.
14 citations
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TL;DR: The natural C*-algebra formalism is employed, and it turns out that one has an allover dualism of language: one can define everything for ( compatible) observables, but also for (compatible) C-subalgebras.
Abstract: This note will introduce some notation and definitions for information theoretic quantities in the context of quantum systems, such as (conditional) entropy and (conditional) mutual information. We will employ the natural C*-algebra formalism, and it turns out that one has an allover dualism of language: we can define everything for (compatible) observables, but also for (compatible) C*-subalgebras. The two approaches are unified in the formalism of quantum operations, and they are connected by a very satisfying inequality, generalizing the well known Holevo bound. Then we turn to communication via (discrete memoryless) quantum channels: we formulate the Fano inequality, bound the capacity region of quantum multiway channels, and comment on the quantum broadcast channel.
3 citations