Continuous variable quantum key distribution (CV-QKD) is arising as an attractive technology for quantum secure communications in future optical networks, thanks to its higher compatibility with conventional telecommunication systems. In fact, CV-QKD adopts opto-electronic devices of coherent optical systems, enabling the use of commercial off-the-shelf components (COTS) and photonic integrated circuits (PICs). This favors a faster and sustainable adoption of this technology in optical networks. Also, smoother integration within the network infrastructure can be envisioned, in coexistence with classical communications, further facilitated and accelerated by software defined networking (SDN). In this invited contribution, the adoption of CV-QKD in future optical networks is discussed, presenting our recent results.
Continuous variable quantum key distribution (CV-QKD) is arising as an attractive technology for quantum secure communications in future optical networks, thanks to its higher compatibility with conventional telecommunication systems. In fact, CV-QKD adopts opto-electronic devices of coherent optical systems, enabling the use of commercial off-the-shelf components (COTS) and photonic integrated circuits (PICs). This favors a faster and sustainable adoption of this technology in optical networks. Also, smoother integration within the network infrastructure can be envisioned, in coexistence with classical communications, further facilitated and accelerated by software defined networking (SDN). In this invited contribution, the adoption of CV-QKD in future optical networks is discussed, presenting our recent results.
Several technological challenges are currently posed by future 6G networks to support ultra-high capacity and dynamic connectivity, while ensuring environmental and societal sustainability, scalability, and reliability. Among them, security is a crucial aspect, particularly considering open and disaggregated networks. Continuous variable quantum key distribution (CV -QKD) is proposed as an appealing solution to ensure long-term security, while facilitating the coexistence with conventional optical communications for a sustainable integration of QKD technology in future 6G networks. In this work, the adoption of CV -QKD in future optical networks is discussed, focusing on the network resources and infrastructure sharing, exploring advanced features, flexibility and programmability, further enabled by software defined networking (SDN).
Future optical networks, envisioning the support of 6G services and related demanding requirements, should provide ultra-high-capacity and reliable connectivity, ensuring sustainability and security. Quantum key distribution (QKD) is a technology to address the limitations of classical cryptography, enabling quantum secure communications. Continuous variable QKD (CV-QKD) offers potential cost savings and enhanced compatibility with classical systems. This facilitates the integration within the network infrastructure, particularly in synergy with software-defined networking (SDN), further promoting interoperability and resource sharing/saving. For the adoption and practical implementation of CV-QKD, it is relevant to consider composable security and a finite number of symbols employed in the protocol (block size). In this work, we present the comparison of two models, to provide a figure of the required block size. We also assess the results using a simulation software. Furthermore, we explore a coexistence scenario considering a flexible grid, to exploit the CV-QKD capability of arbitrarily tuning the operating wavelength. This is a relevant feature enabling flexible allocation of the quantum channel to mitigate impairment and saving spectral resources. Considering realistic parameters aligned to commercially available CV-QKD systems and finite block size, we show an improvement with respect to our previous results. A minimum quantum-classical channel spacing of 112.5 GHz is required in a coexistence scenario with 8×200G transceivers and 9 dBm of total power over a 15 km link. In case of 10 dBm of total power, 125 GHz quantum-classical channel spacing is required to generate keys for practical implementation over the analyzed links. Finally, we discuss SDN aspects relevant for dynamic quantum channel allocation and flexible network management, enabling coexistence and efficient resource sharing, facilitating QKD technology integration in deployed networks. The presented results and envisioned potentialities of CV-QKD for practical implementation in optical networks pave the way for its adoption in the network infrastructure toward future quantum secure communications.
Abstract Quantum key distribution (QKD) represents a cornerstone of secure communication in the quantum era. While discrete-variable QKD (DV-QKD) protocols were historically the first to demonstrate secure key exchange, continuous-variable QKD (CV-QKD) has emerged as a more practical alternative due to its seamless compatibility with current telecommunications infrastructure. CV-QKD relies on coherent and squeezed states of light, offering significant advantages for integration into modern optical networks. This review comprehensively explores the theoretical underpinnings, technological advancements, and practical challenges of CV-QKD. Special attention is given to the role of photonic integrated circuits (PICs) in enabling scalable and efficient implementation of CV-QKD systems. Furthermore, recent advances in machine learning have been leveraged to optimize CV-QKD performance, with data-driven techniques enhancing noise estimation, parameter optimization, and system security. Additionally, tensor networks provide efficient computational tools for analyzing complex quantum correlations, improving the efficiency and robustness of quantum key distribution protocols. These developments, combined with ongoing improvements in quantum photonic integration, pave the way for the practical deployment of large-scale, high-speed quantum-secure networks.
To face the challenges of open and disaggregated 6G networks and the prospect/threat of quantum computing, we propose to adopt continuous-variable QKD (CV-QKD), as a promising technology compatible and suitable to be integrated with conventional optical systems, in combination with software defined networking (SDN). In this work, we present our most recent advances on SDN-enabled flexible CV-QKD for future secure communications. We describe the proposed network architecture, identifying the relevant parameters and interfaces. We consider and analyze a Gaussian-modulated coherent state CV-QKD system, reporting recent experimental results at the varying of the QKD system wavelength, as relevant adaptable parameter, that can be configured by the SDN controller, for distributing highly secure keys in metropolitan networks. The capabilities and potentialities of our proposed approach for future secure communications in open and disaggregated 6G networks are also discussed.
To face the quantum era and the prospect or threat of quantum computing, especially in a disaggregated network environment, the design and implementation of efficient quantum secure communication systems facilitating their integration in the optical network infrastructure is crucial. Quantum key distribution (QKD) is one of the most promising technologies to ensure long-term security. In particular, continuous-variable QKD results as an efficient solution more compatible and suitable to be integrated with conventional optical systems. In this work, quantum secure systems based on QKD for enabling a smooth and sustainable integration in optical networks are introduced, considering the related challenges, towards future secure 6G networks.
The need to increase throughput and reduce the latency in the workload distribution and communications between different Data Centers (DCs) demands the use of dedicated or rented fibers. In view of enabling quantum secure communication in centralized and distributed DC, the integration of quantum key distribution (QKD) systems appears as a crucial milestone to safeguard data against quantum computing threats and the "Store-Now, Decrypt-Later" risk. Specifically, tailored technological solutions must be considered to enable practical deployment. In this context, continuous-variable QKD (CV-QKD) presents a promising approach due to its compatibility with optical systems and potential for cost savings and scalability. The adoption of photonic integrated circuits further enhances feasibility by enabling component miniaturization, reducing power consumption, and facilitating large-scale deployment. An important aspect to consider is optimizing fiber usage to support infrastructure sharing and resource efficiency. Therefore, the coexistence of the proposed QKD solutions with inter-DC communications must be carefully assessed. This invited contribution explores the integration of CV-QKD in DC networks to address flexible and efficient quantum secure connectivity. Envisioned co-propagation scenarios and associated challenges will be discussed, offering insights into the evolutionary path towards quantum secure DC infrastructures.