Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

European Conference on Optical Communication

Co-Existence of Quantum-Key Distribution and Classical Transmission in Space-Division Multiplexed Fiber-Optic Systems: Modelling and Validation Over Field-Deployed Multi-Core Fibers

Qi Wu, Domenico Ribezzo, Giammarco Di Sciullo, S. Cocchi, Divya Ann Shaji, Lucas Zischler, Ruben Soares Luis, Paolo Serena, Chiara Lasagni, A. Bononi, Tetsuya Hayashi, A. Gagliano, Paolo Martelli, Alberto Gatto, Paola Parolari, Pierpaolo Boffi, Davide Bacco, Alessandro Zavatta, Yixiao Zhu, Weisheng Hu, Zenglin Xu, Mark Shtaif, Andrea Marotta, Fabio Graziosi, Antonio Mecozzi, Cristian Antonelli

Published Sep 28, 2025• 0 citations
Publisher

Abstract

We propose an analytical model for inter-core spontaneous Raman scattering noise in multi-core fiber systems with co-existing quantum-key distribution and classical transmission in the C-band. The model is experimentally validated over field-deployed multi-core fibers.
DOI
10.1109/ecoc66593.2025.11263049

Related papers

Telecommunication Compatibility Evaluation for Co-existing Quantum Key Distribution in Homogenous Multicore Fiber

Rui Lin, Aleksejs Udaļcovs, Oskars Ozoliņš +8 more

Quantum key distribution (QKD) is regarded as an alternative to traditional cryptography methods for securing data communication by quantum mechanics rather than computational complexity. Towards the massive deployment of QKD, embedding it with the telecommunication system is crucially important. Homogenous optical multi-core fibers (MCFs) compatible with spatial division multiplexing (SDM) are essential components for the next-generation optical communication infrastructure, which provides a big potential for co-existence of optical telecommunication systems and QKD. However, the QKD channel is extremely vulnerable due to the fact that the quantum states can be annihilated by noise during signal propagation. Thus, investigation of telecom compatibility for QKD co-existing with high-speed classical communication in SDM transmission media is needed. In this paper, we present analytical models of the noise sources in QKD links over heterogeneous MCFs. Spontaneous Raman scattering and inter-core crosstalk are experimentally characterized over spans of MCFs with different refractive index profiles, emulating shared telecom traffic conditions. Lower bounds for the secret key rates and quantum bit error rate (QBER) due to different core/wavelength allocation are obtained to validate intra- and inter-core co-existence of QKD and classical telecommunication.

IEEE Access•Jan 1, 2020•24 citations

Integration of quantum key distribution and high-throughput classical communications in field-deployed multi-core fibers

Qi Wu, Domenico Ribezzo, Giammarco Di Sciullo +23 more

Quantum key distribution (QKD) is a secure communication method for sharing symmetric cryptographic keys based on the principles of quantum physics. Its integration into the fiber-optic network infrastructure is important for ensuring privacy in optical communications. Multi-core fibers (MCFs), the likely building blocks of future high-capacity optical networks, offer new opportunities for such integration. Here, we experimentally demonstrate, for the first time, the coexistence of discrete-variable QKD and high-throughput classical communication in the C-band over a field-deployed MCF with industry standard cladding diameter of 125 μm. Specifically, we demonstrate successful secure-key establishment in one core of a 25.2-km uncoupled-core MCF, while simultaneously loading the remaining three cores with full C-band counter-propagating classical traffic at an aggregate net rate of 110.8 Tb/s. By proposing and experimentally validating an improved analytical model for inter-core spontaneous Raman scattering noise, we find that this configuration is optimal for our deployed MCF link as it is immune to four-wave mixing, that becomes relevant when the quantum and classical signals are propagating in the same direction. Our findings make an important step forward in demonstrating the integration of QKD and classical transmission in uncoupled-core multi-core fibers for next-generation optical communication networks.

Light Science & Applications•Aug 13, 2025•31 citations

Optimization of C-band quantum traffic coexisting with O-band classical traffic: preliminary results

Laura d'Avossa, Elena Montella, Marco Grillo +2 more

The coexistence of quantum and classical signals in the same optical fiber is a critical challenge for the deployment of quantum networks. Indeed, selecting an optimal channel for quantum signal transmission is crucial to minimize noise arising from co-propagating classical signals. This work experimentally investigates spontaneous Raman scattering (SpRS), a major source of noise in signals transmitted along the same fiber. Unlike most previous studies relying on narrow-linewidth laboratory lasers or architectures based on spatial or temporal multiplexing of quantum and classical signals, we employ commercial SFP optical transceivers and standard single-core single-mode fiber for the transmission of quantum and classical signals in the same fiber, reflecting conditions typical of deployed urban fiber infrastructures. Building on these measurements, we derive a compact and predictive model that captures the Raman scattering profile, enabling accurate estimation of SpRS noise as a function of source power, wavelength, and fiber length. A key outcome of this work is that the proposed model is independent of the specific optical source used, demonstrating its generality and robustness. The model can therefore be used for the identification of optimal C-band channels for quantum signal allocation, namely those least affected by SpRS noise generated by co-propagating O-band classical traffic. These results pave the way for a parameter-robust description of Raman scattering applicable to diverse fiber-based systems.

quant-pharXiv:2607.26905•IEEE International Mediterranean Conference on Communications and Networking (MeditCom)•Jul 30, 2026•0 citations

Integration of Quantum Key Distribution and Classical Communications Over Field-Deployed Uncoupled-Core Four-Core Fiber

Qi Wu, Domenico Ribezzo, Giammarco Di Sciullo +8 more

We investigate the integration of quantum key distribution (QKD) into classical optical communication links based on a field-deployed uncoupled-core four-core fiber. We experimentally characterize inter-core spontaneous Raman scattering (IC-SpRS) and evaluate the impact of IC-SpRS and dark counts on QKD performance as the classical traffic load is varied when three cores are used for classical WDM transmission and one for QKD.

IEEE Photonics Conference•Nov 10, 2024•1 citation

Simultaneous transmission of mode-pairing quantum key distribution and classical signals over optical fibers

Chen Yang, Rongzhen Jiao

Abstract In the contemporary era of information technology, cybersecurity has emerged as a pivotal subject. Quantum key distribution (QKD) networks have been implemented in various regions worldwide, demonstrating their superior secure communication capabilities in practice. The integration of QKD with traditional fiber optic networks will facilitate the deployment of upcoming quantum technologies. The recently proposed mode-pairing quantum key distribution (MP-QKD) protocol can drastically improve the transmission distance of QKD, thereby obviating the necessity for complex optical field setups. This paper focuses on the co-transmission of MP-QKD with classical signals in three types of optical fibers (single-mode fiber, few-mode fiber, and multi-core fiber). The Raman noise power in the co-transmission system is calculated, and the performance of MP-QKD is analyzed. The analytical results demonstrate the superiority of MP-QKD compared to other MDI-types in co-fiber transmission scenarios.

Physica Scripta•Mar 6, 2025•2 citations

Field Demonstration of Quantum Key Distribution Coexisting with 110-Tb/s Classical Transmission over Multi-Core Fibers

Qi Wu, Domenico Ribezzo, Giammarco Di Sciullo +23 more

We report, for the first time, a field demonstration of quantum key distribution coexisting with 110- Tb/s full C-band dense wavelength-division multiplexed coherent transmission over field-deployed uncou-pled-core multi-core fibers with a standard 125-µm cladding diameter in L'Aquila, Italy. Various coexistence configurations and transmission distances are evaluated.

European Conference on Optical Communication•Sep 28, 2025•2 citations
Quantum key distribution (QKD) is regarded as an alternative to traditional cryptography methods for securing data communication by quantum mechanics rather than computational complexity. Towards the massive deployment of QKD, embedding it with the telecommunication system is crucially important. Homogenous optical multi-core fibers (MCFs) compatible with spatial division multiplexing (SDM) are essential components for the next-generation optical communication infrastructure, which provides a big potential for co-existence of optical telecommunication systems and QKD. However, the QKD channel is extremely vulnerable due to the fact that the quantum states can be annihilated by noise during signal propagation. Thus, investigation of telecom compatibility for QKD co-existing with high-speed classical communication in SDM transmission media is needed. In this paper, we present analytical models of the noise sources in QKD links over heterogeneous MCFs. Spontaneous Raman scattering and inter-core crosstalk are experimentally characterized over spans of MCFs with different refractive index profiles, emulating shared telecom traffic conditions. Lower bounds for the secret key rates and quantum bit error rate (QBER) due to different core/wavelength allocation are obtained to validate intra- and inter-core co-existence of QKD and classical telecommunication.
Quantum key distribution (QKD) is a secure communication method for sharing symmetric cryptographic keys based on the principles of quantum physics. Its integration into the fiber-optic network infrastructure is important for ensuring privacy in optical communications. Multi-core fibers (MCFs), the likely building blocks of future high-capacity optical networks, offer new opportunities for such integration. Here, we experimentally demonstrate, for the first time, the coexistence of discrete-variable QKD and high-throughput classical communication in the C-band over a field-deployed MCF with industry standard cladding diameter of 125 μm. Specifically, we demonstrate successful secure-key establishment in one core of a 25.2-km uncoupled-core MCF, while simultaneously loading the remaining three cores with full C-band counter-propagating classical traffic at an aggregate net rate of 110.8 Tb/s. By proposing and experimentally validating an improved analytical model for inter-core spontaneous Raman scattering noise, we find that this configuration is optimal for our deployed MCF link as it is immune to four-wave mixing, that becomes relevant when the quantum and classical signals are propagating in the same direction. Our findings make an important step forward in demonstrating the integration of QKD and classical transmission in uncoupled-core multi-core fibers for next-generation optical communication networks.
The coexistence of quantum and classical signals in the same optical fiber is a critical challenge for the deployment of quantum networks. Indeed, selecting an optimal channel for quantum signal transmission is crucial to minimize noise arising from co-propagating classical signals. This work experimentally investigates spontaneous Raman scattering (SpRS), a major source of noise in signals transmitted along the same fiber. Unlike most previous studies relying on narrow-linewidth laboratory lasers or architectures based on spatial or temporal multiplexing of quantum and classical signals, we employ commercial SFP optical transceivers and standard single-core single-mode fiber for the transmission of quantum and classical signals in the same fiber, reflecting conditions typical of deployed urban fiber infrastructures. Building on these measurements, we derive a compact and predictive model that captures the Raman scattering profile, enabling accurate estimation of SpRS noise as a function of source power, wavelength, and fiber length. A key outcome of this work is that the proposed model is independent of the specific optical source used, demonstrating its generality and robustness. The model can therefore be used for the identification of optimal C-band channels for quantum signal allocation, namely those least affected by SpRS noise generated by co-propagating O-band classical traffic. These results pave the way for a parameter-robust description of Raman scattering applicable to diverse fiber-based systems.
Abstract In the contemporary era of information technology, cybersecurity has emerged as a pivotal subject. Quantum key distribution (QKD) networks have been implemented in various regions worldwide, demonstrating their superior secure communication capabilities in practice. The integration of QKD with traditional fiber optic networks will facilitate the deployment of upcoming quantum technologies. The recently proposed mode-pairing quantum key distribution (MP-QKD) protocol can drastically improve the transmission distance of QKD, thereby obviating the necessity for complex optical field setups. This paper focuses on the co-transmission of MP-QKD with classical signals in three types of optical fibers (single-mode fiber, few-mode fiber, and multi-core fiber). The Raman noise power in the co-transmission system is calculated, and the performance of MP-QKD is analyzed. The analytical results demonstrate the superiority of MP-QKD compared to other MDI-types in co-fiber transmission scenarios.