As the development of quantum computers advances, the need for quantum-resistant cryptography becomes urgent and the adoption of quantum key distribution systems is a reality. Continuous-variable QKD (CV-QKD) is attracting considerable attention due to its seamless compatibility with classical optical communication systems. In this paper, we review the key features of CV-QKD protocols, discuss how they distinguish from DV-QKD protocols and present some of the challenges that need to be overcome for widespread adoption.
As the development of quantum computers advances, the need for quantum-resistant cryptography becomes urgent and the adoption of quantum key distribution systems is a reality. Continuous-variable QKD (CV-QKD) is attracting considerable attention due to its seamless compatibility with classical optical communication systems. In this paper, we review the key features of CV-QKD protocols, discuss how they distinguish from DV-QKD protocols and present some of the challenges that need to be overcome for widespread adoption.
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.
Quantum key distribution (QKD) enables secure secret key exchange with information-theoretic security by leveraging the principles of quantum mechanics. Continuous-variable QKD (CV-QKD), which utilizes coherent states and coherent detection, has gained attention as a promising approach due to its seamless integration with existing telecommunications networks. CV-QKD systems, which are built with standard telecommunication components, open the door—through photonic integration technology—to the development of devices that are more affordable, compact, and energy efficient. This paper reviews the current state of the art and highlights our recent progress toward fully integrated CV-QKD systems.
Continuous-variable quantum key distribution (CV-QKD) has emerged as a promising approach for secure quantum communication, offering advantages such as high key generation rates, compatibility with standard telecommunication infrastructure, and potential for integration on photonic chips. This review provides an accessible introduction to the theory of CV-QKD, aimed at researchers entering this rapidly developing field. We focus on fundamental concepts, key protocols, and security analysis essential for understanding CV-QKD systems, with a special emphasis on prepare-and-measure protocols using coherent states under asymptotic security conditions. We explain their equivalence to entanglement-based protocols and detail the security proof framework against collective attacks, encompassing both Gaussian and discrete modulation schemes. We also briefly address more advanced topics, including measurement-device-independent CV-QKD and finite-size security analysis. This work is motivated by Brazil's growing investment in quantum communication technologies. By presenting a clear learning path from basic concepts to advanced topics, this work aims to equip newcomers with the essential tools to engage with current research in CV-QKD, thereby supporting the training of a new generation of researchers in this strategic field.
Continuous Variable Quantum Key Distribution (CV-QKD) is currently experiencing rapid and significant growth. This can be attributed to its capacity to increase resilience to noise and its ease of integration into current optical communication networks. In this article, we review and survey existing work on CV-QKD post-processing techniques, privacy amplification, and key reconciliation. We also classify protocols based on transmission, preparation, and measurement, which allows for a more systematic and organized understanding of protocols, as well as identifying potential vulnerabilities or weaknesses in each component and allowing for targeted improvements to enhance the overall security and efficiency of protocols. Finally, we outline potential research directions and future challenges that require attention to advance the optimization of CV-QKD technology.
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.
Quantum Key Distribution (QKD) protocols have emerged as a promising solution for secure communication, offering provable security guarantees based on the principles of quantum mechanics. an overview of recent advancements and challenges in the field of QKD protocols. We discuss key protocols such as BB84, E91, and continuous-variable QKD, highlighting their theoretical foundations and practical implementations. Furthermore, we explore recent research developments in QKD, including measurement-device-independent QKD, twin-field QKD, and satellite-based QKD. These advancements have expanded the capabilities and applicability of QKD protocols, paving the way for secure communication channels resistant to eavesdropping attacks. However, challenges such as scalability, compatibility with existing infrastructure, and vulnerability to certain attacks remain significant barriers to the widespread deployment of QKD. By addressing these challenges and continuing to innovate in the field of quantum cryptography, we can unlock the full potential of QKD protocols for ensuring the confidentiality and integrity of sensitive information exchange in the digital age.