Next-generation Information and Communication Technology (ICT) infrastructures face growing security challenges as advances in quantum computing threaten the long-term viability of widely deployed cryptographic mechanisms. In response, the research community has been developing quantum-safe security approaches capable of protecting communications against quantum-enabled adversaries. Two complementary directions have emerged: Quantum Key Distribution (QKD), which exploits fundamental principles of quantum mechanics to enable secure key establishment, and Post-Quantum Cryptography (PQC), which relies on classical cryptographic algorithms designed to resist quantum attacks. Each approach presents distinct technical challenges, ranging from the physical constraints and deployment complexity of QKD systems to the performance, implementation, and security analysis of candidate PQC algorithms.
Beyond algorithmic and protocol design, a central challenge lies in integrating quantum-safe technologies into existing and emerging ICT infrastructures. Realizing the benefits of QKD and PQC at scale requires their incorporation into the Internet and optical transport networks without compromising performance, reliability, or operational flexibility. This integration raises fundamental questions regarding network architecture, key management, protocol interoperability, and the coexistence of quantum and classical communication mechanisms.
Key open questions therefore extend from the design of quantum communication networks and hybrid quantum-classical security architectures to the evaluation of system-level performance in realistic deployment scenarios. In particular, the realization of large-scale quantum communication networks raises fundamental challenges related to long-distance scalability, the use of quantum repeaters, and the development of routing algorithms and communication protocols specifically tailored to quantum information exchange. Addressing these challenges calls for interdisciplinary research spanning quantum physics, cryptography, and network engineering, with an emphasis on experimental validation and real-world applicability. In this context, this special issue invites contributions that advance the understanding and practical realization of quantum-safe communications, including novel architectures, protocols, integration strategies, and insights gained from experimental platforms and deployment experience.
Quantum communication, quantum repeaters, quantum key distribution (QKD), post-quantum cryptography (PQC), interoperability
