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September 14, 2020

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Quantum receiver for quadrature phase-shift keying at the single photon level

By Jasminder S. Sidhu, Shuro Izumi, Jonas S. Neergaard-Nielsen, Cosmo Lupo, and Ulrik L. Andersen.

Submitted to arXiv on 7 September 2020.

Quantum enhanced receivers are endowed with resources to achieve higher sensitivities than conventional technologies. For application in optical communications, they provide improved discriminatory capabilities for multiple non-orthogonal quantum states. In this work, we propose and experimentally demonstrate a new decoding scheme for quadrature phase-shift encoded signals. Our receiver surpasses the standard quantum limit and outperforms all previously known non-adaptive detectors at low input powers. Unlike existing approaches, our receiver only exploits auxiliary coherent-state fields, linear optics, and on-off photo-detection. This circumvents the requirement for challenging feed-forward operations that limit communication transmission rates and can be readily implemented with current technology.

Read the whole paper here.