We experimentally demonstrate a quantum receiver based on Kennedy scheme for discrimination between two phase-modulated weak coherent states. The receiver is assembled entirely from the standard fiber-optic elements and operates at the conventional telecom wavelength 1.55 microns. The local oscillator and the signal are transmitted through different optical fibers, and the displaced signal is measured with a high-efficiency superconducting nanowire single-photon detector. We show the discrimination error rate two times below the shot-noise limit.
@article{arxiv.1911.08932,
title = {Sub-shot-noise-limited fiber-optic quantum receiver},
author = {M. L. Shcherbatenko and M. S. Elezov and D. V. Sych and G. N. Goltsman},
journal= {arXiv preprint arXiv:1911.08932},
year = {2020}
}