Coexistence of QKD and classical WDM channels

Florian Hipp, Michael Hentschel, Slaviša Aleksić +2 more

Aristeidis Stathis, Argiris Ntanos, Panagiotis Toumasis +3 more

We propose a WDM-enabled optical architecture in support of optimized classical/QKD coexistence over the deployed fiber/FSO infrastructure for 6G communications. A detailed analysis of 4-channel C-band WDM Classical/Quantum coexistence over deployed fiber/FSO links was conducted, showcasing the feasibility of QKD links for intra-campus connections in both mediums revealing QBER values (<3.2%) under daylight conditions.

Vicente Martín Ayuso

Paolo Martelli, Marco Brunero, Paola Parolari +3 more

Masab Iqbal, Michela Svaluto Moreolo, Arturo Villegas +2 more

Quantum Key Distribution (QKD) offers a secure method for generating cryptographic keys crucial for 6G future networks. It relies on quantum mechanics principles to guarantee protection against potential threats from quantum computers. However, QKD signal is fragile and can be easily degraded by external noise sources. Therefore, integrating QKD into existing networks poses a challenge, as it must seamlessly coexist with classical channels, in optical fiber links utilizing wavelength division multiplexing (WDM). Continuous-variable QKD (CV-QKD), which leverages optical coherent technology, is seen as a promising solution for this integration within current telecom infrastructure. Additionally, Software-Defined Networking (SDN) presents opportunities for enhancing efficiency and facilitating dynamic management in coexistence scenarios. This paper reports key noise sources that degrade CV-QKD performance in coexistence and the parameters contributing to these noise sources such as classical channel (CC) power, separation between CC and quantum channel (QC) and position of QC. We also report strategies for effectively managing coexistence scenarios using SDN. We focus on the coexistence of CVQKD in presence of classical channels spaced according a 100 GHz ITU-T grid over a 10 km link length, providing guidelines to optimize the performance.

Xueqin Ren, Yongmei Sun, Weiwen Kong +1 more

Wavelength division multiplexing (WDM) and space division multiplexing (SDM) can be used to implement coexistence of the classical and quantum signals. But some noises are introduced due to the SDM/WDM techniques, such as Raman, Four-wave mixing and inter-core crosstalk noises, which will restrict the performance of the quantum key distribution system (QKD). In this paper, we consider that the classical optical communication system is also affected by such noises. So, in order to improve the performance of the coexistence system based on WDM and SDM, we propose a dual optimized core and wavelength allocation (DOCWA) scheme to realize the synergistic transmission of classical and quantum signals over multi-core fiber. Experiments verify that the proposed scheme can suppress noise photons on classical and quantum channels up to 152.71% and 167.28% compared to the quantum equal frequency spacing scheme, respectively.