Finite key analysis of experimentally realized practical COW-QKD protocol

TL;DR

This paper reports an experimental implementation of the COW-QKD protocol, providing a finite key analysis framework and demonstrating secure key rates over medium-range fiber links under realistic conditions.

Contribution

It introduces a practical finite key analysis framework for COW-QKD and applies it to experimental data to evaluate security and key rates.

Findings

Secure key rates of 1.2 to 1.6 kbps achieved

Secure communication over ~156 km fiber with realistic parameters

Finite key analysis confirms security under experimental conditions

Abstract

An experimental implementation of the Coherent One-Way Quantum Key Distribution (COW-QKD) protocol is reported under realistic conditions, and a clean and easy-to-use framework for performing finite key analysis of the COW-QKD protocol is provided by extending a set of existing results. The framework provided here is used to perform finite key rate analysis of the COW-QKD protocol with respect to the actual parameters used in the experimental realization reported here. The system is kept running for several hours with different experimental parameters and stable secure key rates between 1.2 to 1.6 kbps are observed. In addition, QBER, phase error rate and secure key rate are obtained under finite key analysis, and it is shown that COW-QKD is secure for medium-range transmissions (up-to ~ 156 (171) km of optical fiber with 0.2 dB loss per km if detector efficiency is 0.1 (0.2) and other parameters are same as those used in this experiment).