In recent years, quantum network technology has been rapidly developing, with new theories, solutions, and protocols constantly emerging. The breakthrough experiments and achievements are impressive, such as the construction and operation of ultra-long-distance and multi-user quantum key distribution (QKD) networks, the proposal, verification, and experimental demonstration of new network nonlocality characteristics, etc. The results of recent research on QKD and network nonlocality are summarized and analyzed in this paper, including CV-MDI-QKD (continuous-variable measurement-device-independent QKD), TF-QKD (twin-field QKD), AMDI-QKD (asynchronous MDI-QKD), the generalization, sharing, and certification of network nonlocality, as well as the main achievements and related research tools of full network nonlocality and genuine network nonlocality, aiming to identify the current status and future development paths of the QKD and network nonlocality.
In recent years, quantum network technology has been rapidly developing, with new theories, solutions, and protocols constantly emerging. The breakthrough experiments and achievements are impressive, such as the construction and operation of ultra-long-distance and multi-user quantum key distribution (QKD) networks, the proposal, verification, and experimental demonstration of new network nonlocality characteristics, etc. The results of recent research on QKD and network nonlocality are summarized and analyzed in this paper, including CV-MDI-QKD (continuous-variable measurement-device-independent QKD), TF-QKD (twin-field QKD), AMDI-QKD (asynchronous MDI-QKD), the generalization, sharing, and certification of network nonlocality, as well as the main achievements and related research tools of full network nonlocality and genuine network nonlocality, aiming to identify the current status and future development paths of the QKD and network nonlocality.
Quantum key distribution (QKD) is a straightforward cryptographic protocol for secure communication using quantum mechanics principles. This book chapter provides an introduction to QKD protocols based on theoretical principles, applicability, and recent advancements. The chapter provides an overview of the most popular BB84 protocol and its extensions, including measurement-device-independent QKD (MDI-QKD) and twin-field QKD (TF-QKD). The chapter includes continuous-variable QKD (CV-QKD) and its applicability to real networks. Security attacks, including side-channel attacks and photon-number splitting (PNS) attacks, are addressed with a focus on countermeasures, including decoy-state techniques and device-independent protocols. Application of QKD for network security, cloud computing, and critical infrastructure is addressed. Integration of QKD with classical cryptography techniques, post-quantum cryptography, and innovative quantum network topologies is addressed to investigate applicability for large-scale implementation. The chapter discusses recent advancements in superconducting nanowire single-photon detectors, quantum memory-assisted QKD, and free-space QKD in atmospheric channels. It also discusses innovative reconciliation techniques, authentication schemes, future developments, and deployment challenges and provides valuable information for researchers and practitioners.
As quantum key distribution (QKD) emerges as a robust defence against quantum computer threats, significant advancements have been realised by researchers. A pivotal focus has been the development of protocols that not only simplify hardware implementation, such as the use of continuous-variable (CV) systems, but also eliminate the necessity for trusted nodes, as seen with the measurement-device-independent (MDI) approach. This paper delves into the integration of these methodologies in the CV-MDI-QKD protocol, offering an in-depth exploration of its evolution, primary characteristics, and the latest advancements in both theory and experiment.
The emergence of the Quantum computing technologies is imposing greater threats on the existing cryptographic algorithms that rely heavily on the mathematical problems, creating a growing demand for quantum safe Communication. Even though Quantum Key Distribution (QKD) is a theoretically proven secure key exchange method against quantum attacks, it also faces several deployment challenges like scalability, cost, and interoperability limitations. A systematic review was conducted to examine the recent advancements in QKD technologies by analyzing the peer reviewed studies Published between 2021 to 2025 and classified according to protocol design, network architecture and deployment readiness. The review analyzed articles for a Comparison of the recent advancements in the field of Twin Field QKD, Continuous Variable QKD, Hybrid classical quantum networks and long-distance secure communication systems. Furthermore, the review also examined the Conjunction of QKD with the emerging security applications of 5G Networks, IOT environments, edge computing, fog Computing and Multimedia security systems. Despite of the significant technological advancements, the deployment of QKD is still under the constraints of scalability, lower key generation rates, cost of deployment, Synchronization issues, stability complexities, interoperability problems and standardization issues. Through a comprehensive evaluation of QKD protocols and network architectures, this study highlights the critical research gaps and provides future directions for the practical deployment of the QKD enabled secure communication networks.
Quantum Key Distribution (QKD) supports the negotiation and sharing of private keys with unconditional security between authorized parties. Over the years, theoretical advances and experimental demonstrations have successfully transitioned QKD from laboratory research to commercial applications. As QKD expands its reach globally, it encounters challenges such as performance limitations, cost, and practical security concerns. Nonetheless, innovations in satellite-based QKD and the development of new protocols are paving the way towards a worldwide network. In this review, we provide an overview of QKD implementations, with a focus on protocols, devices, and quantum channels. We discuss the challenges of practical QKD and explore long-haul QKD. Additionally, we highlight the future research directions that are expected to significantly advance the realization of a global QKD network.
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.
Quantum Key Distribution (QKD) constitutes one of the most profound practical applications of quantum mechanics, enabling two parties to exchange cryptographic keys whose security is guaranteed by the fundamental laws of physics rather than the assumed computational hardness of mathematical problems. As quantum computing capabilities continue to advance, classical public-key infrastructure faces an existential threat, rendering QKD a critical component of post-quantum secure communication architectures. This paper presents a comprehensive survey of QKD spanning foundational protocols, rigorous security proofs, hardware implementation challenges, deployment experiences across metropolitan fiber networks, and recent satellite-based experiments. We analyze the BB84, E91, B92, SARG04, continuous-variable, measurement-device-independent (MDI-QKD), and twin-field (TF-QKD) protocols in depth, examining their security assumptions, achievable key rates, and practical limitations. Particular attention is given to side-channel vulnerabilities in realistic implementations, decoy-state methods for mitigating photon-number-splitting attacks, and finite-key security analysis. We review key performance benchmarks from commercial systems and discuss integration with classical network infrastructure. The paper concludes by identifying open challenges in quantum repeater development, satellite QKD scalability, and standardization efforts essential for large-scale deployment.