Reviewing Quantum Key Distribution and the Path to a Secure Quantum Internet
Keywords:
Quantum communication, Quantum entanglement, Quantum internet, Quantum key distribution, Quantum repeatersAbstract
Quantum communication uses the fundamental principles of quantum mechanics, namely superposition, entanglement, and the no-cloning theorem, to transmit information with security guarantees that classical cryptography cannot offer. As classical public-key infrastructure faces long-term threats from quantum computers running Shor's algorithm, quantum communication has emerged as a leading candidate for future-proof secure networking. This article reviews the theoretical foundations of quantum communication, surveys prominent Quantum Key Distribution (QKD) protocols including BB84, E91, decoy-state, continuous-variable, and twin-field QKD, and examines the practical barriers of photon loss, decoherence, and detector imperfections that limit transmission distance. A comparative analysis of protocol performance over optical fiber is presented, followed by a discussion of quantum repeater architectures and satellite-based quantum key distribution as complementary strategies for extending range. Recent milestones, including intercontinental satellite quantum key distribution and metropolitan quantum networks, are discussed alongside persistent engineering and cost challenges. The article concludes with a forward-looking perspective on the quantum internet, highlighting the integration of quantum communication with quantum computing and distributed quantum sensing as the next frontier of the field.
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