Sub-shot-noise-limited fiber-optic quantum receiver
Michael Shcherbatenko, Mikhail S. Elezov, Gregory N Gol'tsman, Сыч Денис Васильевич · Physical Review A · 2020
We experimentally demonstrate a quantum receiver based on the Kennedy scheme for discrimination between two phase-modulated weak coherent states. The receiver is assembled entirely from standard fiber-optic elements and operates at a conventional telecom wavelength of 1.55 $\ensuremath{\mu}\text{m}$. 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 is two times below that of a shot-noise-limited receiver with the same system detection efficiency.