Sub-shot-noise-limited fiber-optic quantum receiver

TL;DR

This paper demonstrates a fiber-optic quantum receiver operating at telecom wavelengths that surpasses the shot-noise limit in discrimination error rate using standard components and superconducting detectors.

Contribution

The work presents the first experimental realization of a fiber-optic quantum receiver that achieves sub-shot-noise performance with standard telecom components.

Findings

Error rate is two times below shot-noise limit.

Operates entirely with standard fiber-optic elements at 1.55 microns.

Uses superconducting nanowire single-photon detectors.

Abstract

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.