Frequency-Division Multiplexed CV-QKD System

TL;DR

This paper introduces a frequency-division multiplexed CV-QKD system that significantly increases spectral efficiency and demonstrates improved secret key rates over multiple channels and distances.

Contribution

The paper presents the first experimental demonstration of a dense FDM-CV-QKD system with multiple channels, achieving higher secret key rates than single-channel systems.

Findings

3.7-fold secret key rate gain in back-to-back scenario

Effective over distances up to 41.1 km

Demonstrated dense multiplexing of low-symbol-rate signals

Abstract

We propose a frequency-division multiplexed (FDM) continuous-variable quantum key distribution (CV-QKD) system with enhanced spectral efficiency through dense multiplexing of low-symbol-rate signals. A four-channel 10-Mbaud FDM-CV-QKD system was experimentally demonstrated using Gaussian modulation, a transmitted local oscillator, and homodyne detection. Under a finite-size scenario (N = 10^7), the system achieved a 3.7-fold back-to-back secret key rate gain and outperformed the single-channel system for distances up to 41.1 km.