Classical capacity of bosonic broadcast communication and a minimum output entropy conjecture

Saikat Guha, Jeffrey H. Shapiro, Baris I. Erkmen

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Abstract

Previous work on the classical information capacities of bosonic channels has established the capacity of the single-user pure-loss channel, bounded the capacity of the single-user thermal-noise channel, and bounded the capacity region of the multiple-access channel. The latter is a multiple-user scenario in which several transmitters seek to simultaneously and independently communicate to a single receiver. We study the capacity region of the bosonic broadcast channel, in which a single transmitter seeks to simultaneously and independently communicate to two different receivers. It is known that the tightest available lower bound on the capacity of the single-user thermal-noise channel is that channel's capacity if, as conjectured, the minimum von Neumann entropy at the output of a bosonic channel with additive thermal noise occurs for coherent-state inputs. Evidence in support of this minimum output entropy conjecture has been accumulated, but a rigorous proof has not been obtained. We propose a minimum output entropy conjecture that, if proved to be correct, will establish that the capacity region of the bosonic broadcast channel equals the inner bound achieved using a coherent-state encoding and optimum detection. We provide some evidence that supports this conjecture, but again a full proof is not available.

Original languageEnglish (US)
Article number032303
JournalPhysical Review A - Atomic, Molecular, and Optical Physics
Volume76
Issue number3
DOIs
Publication statusPublished - Sep 4 2007
Externally publishedYes

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ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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