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arXiv · 1703.05701

The capacity of coherent-state adaptive decoders with interferometry and single-mode detectors

Matteo Rosati·Andrea Mari·Vittorio Giovannetti
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Abstract

A class of Adaptive Decoders (AD's) for coherent-state sequences is studied, including in particular the most common technology for optical-signal processing, e.g., interferometers, coherent displacements and photon-counting detectors. More generally we consider AD's comprising adaptive procedures based on passive multi-mode Gaussian unitaries and arbitrary single-mode destructive measurements. For classical communication on quantum phase-insensitive Gaussian channels with a coherent-state encoding, we show that the AD's optimal information transmission rate is not greater than that of a single-mode decoder. Our result also implies that the ultimate classical capacity of quantum phase-insensitive Gaussian channels is unlikely to be achieved with the considered class of AD's.

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Matteo Rosati, Andrea Mari, Vittorio Giovannetti. 2017-07-18. The capacity of coherent-state adaptive decoders with interferometry and single-mode detectors. https://doi.org/10.1103/physreva.96.012317

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