Coherent state coding approaches the capacity of non-Gaussian bosonic channels

Abstract

The additivity problem asks if the use of entanglement can boost the information-carrying capacity of a given channel beyond what is achievable by coding with simple product states only. This has recently been shown not to be the case for phase-insensitive one-mode Gaussian channels, but remains unresolved in general. Here we consider two general classes of bosonic noise channels, which include phase-insensitive Gaussian channels as special cases: these are beamsplitters with general, potentially non-Gaussian environment states and classical noise channels with general probabilistic noise. We show that additivity violations, if existent, are rather minor for all these channels: the maximal gain in classical capacity is bounded by a constant independent of the input energy. Our proof shows that coding by simple classical modulation of coherent states is close to optimal.

arXiv comment19 pages, 2 figures; updated to match published version

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Cited by in corpus (5)

• Resource theory of non-Gaussian operations
• The conditional entropy power inequality for quantum additive noise channels
• Upper bounds on the quantum capacity for general attenuator and amplifier
• Upper bounds on the private capacity for bosonic Gaussian channels
• Weighted $p$-Rényi Entropy Power Inequality: Information Theory to Quantum Shannon Theory