Twin-Field Quantum Key Distribution: Protocols, Security, and Open Problems

• URL: http://arxiv.org/abs/2510.26320v1
• Date: Thu, 30 Oct 2025 10:14:09 GMT
• Title: Twin-Field Quantum Key Distribution: Protocols, Security, and Open Problems
• Authors: Syed M. Arslan, Syed Shahmir, Noureldin Mohammad, Saif Al-Kuwari, Muataz Alhussein,
• Abstract summary: Twin-Field Quantum Key Distribution (TF-QKD) has emerged as a potential protocol for long distance secure communication.<n>By having two parties transmit phase encoded weak coherent pulses to an untrusted central node, the TF-QKD exploits single-photon interference to achieve secret key rates scaling as square-root of channel length.<n>This survey provides a comprehensive survey of TF-QKD, covering the original protocol, its fundamental principles, and key-rate derivation.
• Score: 0.0
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: Twin-Field Quantum Key Distribution (TF-QKD) has emerged as a potential protocol for long distance secure communication, overcoming the rate-distance limitations of conventional quantum key distribution without requiring trusted repeaters. By having two parties transmit phase encoded weak coherent pulses (WCP) to an untrusted central node, the TF-QKD exploits single-photon interference to achieve secret key rates scaling as square-root of channel length, enabling quantum-secured communication over unprecedented distances. This survey provides a comprehensive survey of TF-QKD, covering the original protocol, its fundamental principles, and key-rate derivation. We discuss major TF-QKD variants, including Phase-Matching QKD and Sending-or-Not-Sending QKD, with various improved versions. We compare their performance, implementation trade-offs, protocol-specific vulnerabilities, and countermeasures. The survey summarizes security proofs ranging from asymptotic decoy-state analyses to finite-key composable frameworks, experimental milestones, technological enablers, and practical deployment challenges. Finally, we outline open problems in the field and present a roadmap for integrating TF-QKD into scalable quantum networks, underscoring its central role in the future quantum internet.

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