Quantum key distribution(QKD) network can be differentiated into three main categories based on different family of node functionalities:1)trusted relay node;2)optical node;and 3)quantum node.The au-thor discusses the architecture of these three different networks,as well as analyzes their performances,appli-cable conditions and application prospect,respectively.At last,the author points out that users are supposed to choose different network models according to their particular needs.
Quantum key distribution(QKD) network can be differentiated into three main categories based on different family of node functionalities:1)trusted relay node;2)optical node;and 3)quantum node.The au-thor discusses the architecture of these three different networks,as well as analyzes their performances,appli-cable conditions and application prospect,respectively.At last,the author points out that users are supposed to choose different network models according to their particular needs.
We evaluate the performance of two architectures for network-wide quantum key distribution (QKD): Relayed QKD, which relays keys over multi-link QKD paths for non-adjacent nodes, and Switched QKD, which uses optical switches to dynamically connect arbitrary QKD modules to form direct QKD links between them. An advantage of Switched QKD is that it distributes quantum keys end-to-end, whereas Relayed relies on trusted nodes. However, Switched depends on arbitrary matching of QKD modules. We first experimentally evaluate the performance of commercial DV-QKD modules; for each of three vendors we benchmark the performance in standard/matched module pairs and in unmatched pairs to emulate configurations in the Switched QKD network architecture. The analysis reveals that in some cases a notable variation in the generated secret key rate (SKR) between the matched and unmatched pairs is observed. Driven by these experimental findings, we conduct a comprehensive theoretical analysis that evaluates the network wide performance of the two architectures. Our analysis is based on uniform ring networks, where we derive optimal key management configurations and analytical formulas for the achievable consumed SKR. We compare network performance under varying ring sizes, QKD link losses, QKD receivers' sensitivity and performance penalties of unmatched modules. Our findings indicate that Switched QKD performs better in dense rings (short distances, large node counts), while Relayed QKD is more effective in longer distances and large node counts. Moreover, we confirm that unmatched QKD modules penalties significantly impact the efficiency of Switched QKD architecture.
Quantum Key Distribution (QKD) has emerged as a promising technology for secure the communication because its security is achieved through the physical laws of quantum mechanics, rather than being based on mathematical problems. In most of the earlier implementations, QKD relied on the direct exchange of the secret keys between two users. Once implemented in a practical system outside of a controlled laboratory setting, QKD experiences complications associated with the limited distances, communication losses, and vulnerabilities to eavesdropping in the multi-user network configurations, compromising its ability to be this third-generation secure communication system. In this work, we show how quantum relay nodes can be implemented as points along a QKD network. The relay nodes provide additional advantages such as extending the communication distances, increasing eavesdropping resistance and allowing for more sophisticated configurations. While relying on theoretical models and experimentally motivated studies, this paper discusses advantages of implementing a relay architecture into a QKD network and highlights technical difficulties that need to be addressed prior to widespread implementation.
The rise of quantum computers threatens public-key cryptography and its foundational role in secure symmetric key distribution. Quantum Key Distribution (QKD) offers a promising alternative, leveraging quantum principles to securely distribute keys between two endpoints. To enable network-wide key distribution, two main architectures have emerged: Relayed QKD, which forwards keys generated between neighbors along a path, and Switched QKD, which uses optical switches to dynamically establish QKD links between nodes for scheduled key generation sessions. Both architectures require algorithmic solutions for efficient key management and distribution. We present optimal configurations and analytical formulas for uniform rings and compare the performance of the two architectures. We also define generic key management algorithms and apply them to compare the two architectures in non-uniform rings. Our findings are consistent across both uniform and non-uniform rings: Switched QKD is more effective in dense networks (i.e., with many nodes and short distances), while Relayed QKD performs better in larger rings with longer inter-node distances.
As a promising quantum application, Quantum Key Distribution (QKD) technology has been rapidly developed from point-to-point communication to a large-scale commercial network. However, considering the cost of QKD components and network infrastructure, building a QKD network is challenged by its expensive capital expenditure, which significantly hinders its future popularization. In this article, we envision an evolution roadmap consisting of three stages for the future development of QKD networks, aiming at achieving a fully integrated network architecture that combines QKD and telecommunications networks. Powered by several critical technologies, such as link multiplexing, miniaturized QKD, and transmission optimization, QKD is foreseen to be integrated into telecommunications networks as an add-on module that can be flexibly deployed. After that, we introduce the integrated network architecture design in detail, and respectively provide four QKD-related function implementations. At last, key technologies that should be concerned and further investigated are also discussed with performance evaluation, which can provide theoretical guidance for both industries and academia. Based on the proposed roadmap and integrated architecture, we believe a scalable, easy-to-use, and affordable QKD service can be brought to current telecommunication networks, and extensively applied by ordinary people while using daily applications.
Quantum key distribution (QKD) protocols generate a same secret key at two nodes which are at different locations. Such key is used to encrypt and decrypt messages for unconditionally secure communications through a classical channel. Originally, QKD protocols are designed to work between two nodes which are directly connected through a point-to-point quantum channel. Currently, commercial QKD systems have limited range and key rate. To increase key rate and extend range, the key generated by QKD at one end node is relayed hop-by-hop to the other end node through multiple trusted nodes. In a QKD network with multiple pairs of communicating nodes, routing deals with the issue of deciding for each pair, which trusted nodes are used to form a path connecting the end nodes. This paper presents an overview of QKD and highlights the differences between QKD routing as compared to classical routing. The challenges of QKD routing are presented. Existing works dealing with the challenges are surveyed. This paper ends with a discussion on remaining research issues.
In order to explore the solution of the problems of the short of knowledge and immature theoretical research about large scale,specifically wide-area,quantum key distribution network research,the structure model,the secret key model and the active model of the trusted relaying quantum key distribution network were proposed from the viewpoints of structure,inner secret key relationship and working principle respectively for the trusted relaying quantum key distribution network which is the only real practical one so far.Firstly,from the viewpoint of system theory,the quantum key distribution network was divided into five layers according to the basic principle of key relaying based on the existing structure model.The constitution of each layer and the relationship between them were explained in detail.Secondly,from the viewpoint of information theory,the quantum key distribution network was abstracted as a key information graph according to the key sharing relationship among all nodes and the node and edge were formally defined.Therefore,the secret key information in the five layers quantum key distribution network could be explained by the graph theory in details.Lastly,from the viewpoint of the cybernetics, the key distribution process was resolved into two basic parts of key relationship establishment and secrete key generation,then the works of the quantum key distribution network could be explained by the development of key information graphs.The analysis showed that the proposed quantum key distribution network model can achieve the goal of hierarchical,parallel and pipelining key distribution,and can ensure the security of key distribution,which establishes the foundation for the future theoretical and technology research.