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arXiv · 1303.4939

Equivalence Relations for the Classical Capacity of Single-Mode Gaussian Quantum channels

Joachim Schäfer·Evgueni Karpov·Raúl García-Patrón·Oleg V. Pilyavets·Nicolas J. Cerf
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Abstract

We prove the equivalence of an arbitrary single-mode Gaussian quantum channel and a newly defined fiducial channel preceded by a phase shift and followed by a Gaussian unitary operation. This equivalence implies that the energy-constrained classical capacity of any single-mode Gaussian channel can be calculated based on this fiducial channel, which is furthermore simply realizable with a beam splitter, two identical single-mode squeezers, and a two-mode squeezer. In a large domain of parameters, we also provide an analytical expression for the Gaussian classical capacity, exploiting its additivity, and prove that the classical capacity cannot exceed it by more than 1/ln2 bits.

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Joachim Schäfer, Evgueni Karpov, Raúl García-Patrón, Oleg V. Pilyavets, Nicolas J. Cerf. 2013-03-20. Equivalence Relations for the Classical Capacity of Single-Mode Gaussian Quantum channels. https://doi.org/10.1103/physrevlett.111.030503

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