Multiplexing of Continuous-Variable and Discrete-Variable Quantum Key Distribution Systems over Fibered and Free-Space Channels
Abstract
Future quantum communication infrastructures will need to serve heterogeneous users on shared physical channels: short-range, high-throughput links favor Continuous-Variable Quantum Key Distribution (CV-QKD), while long-reach, high-loss links remain the domain of Discrete-Variable QKD (DV-QKD). Wavelength-division multiplexing (WDM) of the two protocols on a common channel would address both regimes simultaneously, but their markedly different noise sensitivities make coexistence non-trivial and, to date, experimentally untested. Here we report the first simultaneous operation of two independent CV-and DV-QKD systems on a common optical channel, using standard C-band DWDM filters at 1550.12 nm (CV) and 1545.32 nm (DV). We demonstrate joint operation on both optical fiber and a 620 m urban daylight free-space link. On fiber, the two systems exhibit the expected complementarity, crossing over at 7.56 dB of channel loss where both deliver ∼1.43 Mbit/s; in daylight free-space, both sustain Mbit/s key rates under time-varying atmospheric attenuation. Across all configurations we observe no measurable multiplexing-induced penalty in QBER or excess noise. These results establish hybrid CV-DV WDM as a practical building block for heterogeneous quantum communication networks, where metropolitan high-throughput users and long-reach backbone links can be served on a single physical infrastructure.
Related
- Wavelength-shifting attack on a chip-based continuous-variable quantum key distribution system
- Effective discrete-modulated continuous variable QKD under general attacks using dimension reduction
- Coherent receiver for Continuous-Variable Quantum Key Distribution using a 3 × 3 beam splitter and single-ended photodetectors
- Continuous variable quantum key distribution through a fading channel with minimal information leakage
- Efficient Simulation of Hybrid Continuous- and Discrete-Variable Quantum Circuits via Gaussian Decompositions
BibTeX
@misc{sabatini2026multiplexing,
title = {{Multiplexing of Continuous-Variable and Discrete-Variable Quantum Key Distribution Systems over Fibered and Free-Space Channels}},
author = {Mattia Sabatini and Edoardo Rossi and Matías R. Bolaños and Francesco Vedovato and Thomas Liege and Eleni Diamanti and Giuseppe Vallone and Paolo Villoresi and Yoann Piétri and Marco Avesani},
howpublished = {HAL},
year = {2026},
month = aug,
eprint = {2608.19745},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05738344v1},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Multiplexing of Continuous-Variable and Discrete-Variable Quantum Key Distribution Systems over Fibered and Free-Space Channels
AU - Mattia Sabatini
AU - Edoardo Rossi
AU - Matías R. Bolaños
AU - Francesco Vedovato
AU - Thomas Liege
AU - Eleni Diamanti
AU - Giuseppe Vallone
AU - Paolo Villoresi
AU - Yoann Piétri
AU - Marco Avesani
PY - 2026
DA - 2026/08/21
PB - HAL
UR - https://hal.science/hal-05738344v1
AB - Future quantum communication infrastructures will need to serve heterogeneous users on shared physical channels: short-range, high-throughput links favor Continuous-Variable Quantum Key Distribution (CV-QKD), while long-reach, high-loss links remain the domain of Discrete-Variable QKD (DV-QKD). Wavelength-division multiplexing (WDM) of the two protocols on a common channel would address both regimes simultaneously, but their markedly different noise sensitivities make coexistence non-trivial and, to date, experimentally untested. Here we report the first simultaneous operation of two independent CV-and DV-QKD systems on a common optical channel, using standard C-band DWDM filters at 1550.12 nm (CV) and 1545.32 nm (DV). We demonstrate joint operation on both optical fiber and a 620 m urban daylight free-space link. On fiber, the two systems exhibit the expected complementarity, crossing over at 7.56 dB of channel loss where both deliver ∼1.43 Mbit/s; in daylight free-space, both sustain Mbit/s key rates under time-varying atmospheric attenuation. Across all configurations we observe no measurable multiplexing-induced penalty in QBER or excess noise. These results establish hybrid CV-DV WDM as a practical building block for heterogeneous quantum communication networks, where metropolitan high-throughput users and long-reach backbone links can be served on a single physical infrastructure.
ER -