Stable polarization-encoded quantum key distribution in fiber

TL;DR

This paper demonstrates a long-term stable polarization control method for quantum key distribution over long-distance fibers, maintaining low error rates suitable for secure quantum communication.

Contribution

It introduces an active feedback technique that achieves over 10 hours of stable polarization control in fibers up to 100 km, enabling reliable polarization-encoded QKD.

Findings

Stable polarization control over 10 hours in 50-100 km fibers

Quantum bit error rates below security threshold

Supports long-distance, one-way fiber QKD systems

Abstract

Polarizations of single-photon pulses have been controlled with long-term stability of more than 10 hours by using an active feedback technique for auto-compensation of unpredictable polarization scrambling in long-distance fiber. Experimental tests of long-term operations in 50, 75 and 100 km fibers demonstrated that such a single-photon polarization control supported stable polarization encoding in long-distance fibers to facilitate stable one-way fiber system for polarization-encoded quantum key distribution, providing quantum bit error rates below the absolute security threshold.