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Time-Delay Attack and Mitigation Technique for Remote Identification of Entangled Photon Pairs

Abebu Ademe Bayleyegn, Milad Ghadimi, Muhammad Idham Habibie, Riccardo Bassoli, Frank H. P. Fitzek

Published Sep 9, 2025• 0 citations
Publisher

Abstract

Quantum technologies, leveraging the principles of quantum mechanics, are rapidly advancing and offer transformative benefits in secure communication, computation, and sensing. While quantum communication systems provide unprecedented data security, the implementation security of quantum communication protocols still needs investigation. In this regard, the security of Quantum Key Distribution (QKD) is well studied, while there is limited research on quantum communication protocols beyond QKD. In this work, we study time-delay attacks on generic entanglement distribution quantum communication networks. These networks rely heavily on precise time synchronization between detection stations and a preset coincidence window for accurate identification of distributed entangled pairs. An eavesdropper can exploit this reliance on correct photon arrival timing by introducing a time delay, causing genuine entangled pairs to fall outside the coincidence window. This leads to missed detections, potential false pair identifications, or denial-of-service (DoS) conditions. To mitigate this vulnerability, we propose photon arrival-time monitoring and threshold-based time-delay detection, enabling adaptive coincidence window adjustment. By dynamically centering the coincidence window on the mean photon arrival time, valid entangled pairs can still be accurately identified, even in the presence of a time-delay attack. We simulate the quantum measurement process under different time-delay insertion values in the quantum channel, assuming perfectly synchronized remote detection stations. Our results show the impact of time-delay attacks on entangled pair detection rates, detection accuracy, and fidelity of the reconstructed Bell state. The effectiveness of our proposed countermeasure is demonstrated in simulation, showing that it maintains both the photon count rate and the fidelity at high levels, even when an eavesdropper introduces time delays in the quantum channel.

DOI
10.36227/techrxiv.175745151.14002556/v1

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Quantum technologies, leveraging the principles of quantum mechanics, are rapidly advancing and offer transformative benefits in secure communication, computation, and sensing. While quantum communication systems provide unprecedented data security, the implementation security of quantum communication protocols still needs investigation. In this regard, the security of Quantum Key Distribution (QKD) is well studied, while there is limited research on quantum communication protocols beyond QKD. In this work, we study time-delay attacks on generic entanglement distribution quantum communication networks. These networks rely heavily on precise time synchronization between detection stations and a preset coincidence window for accurate identification of distributed entangled pairs. An eavesdropper can exploit this reliance on correct photon arrival timing by introducing a time delay, causing genuine entangled pairs to fall outside the coincidence window. This leads to missed detections, potential false pair identifications, or denial-of-service (DoS) conditions. To mitigate this vulnerability, we propose photon arrival-time monitoring and threshold-based time-delay detection, enabling adaptive coincidence window adjustment. By dynamically centering the coincidence window on the mean photon arrival time, valid entangled pairs can still be accurately identified, even in the presence of a time-delay attack. We simulate the quantum measurement process under different time-delay insertion values in the quantum channel, assuming perfectly synchronized remote detection stations. Our results show the impact of time-delay attacks on entangled pair detection rates, detection accuracy, and fidelity of the reconstructed Bell state. The effectiveness of our proposed countermeasure is demonstrated in simulation, showing that it maintains both the photon count rate and the fidelity at high levels, even when an eavesdropper introduces time delays in the quantum channel.
Quantum technologies, leveraging the principles of quantum mechanics, are rapidly advancing and offer transformative benefits in secure communication, computation, and sensing. While quantum communication systems provide unprecedented data security, the implementation security of quantum communication protocols still needs investigation. In this regard, the security of Quantum Key Distribution (QKD) is well studied, while there is limited research on quantum communication protocols beyond QKD. In this work, we study time-delay attacks on generic entanglement distribution quantum communication networks. These networks rely heavily on precise time synchronization between detection stations and a preset coincidence window for accurate identification of distributed entangled pairs. An eavesdropper can exploit this reliance on correct photon arrival timing by introducing a time delay, causing genuine entangled pairs to fall outside the coincidence window. This leads to missed detections, potential false pair identifications, or denial-of-service (DoS) conditions. To mitigate this vulnerability, we propose photon arrival-time monitoring and threshold-based time-delay detection, enabling adaptive coincidence window adjustment. By dynamically centering the coincidence window on the mean photon arrival time, valid entangled pairs can still be accurately identified, even in the presence of a time-delay attack. We simulate the quantum measurement process under different time-delay insertion values in the quantum channel, assuming perfectly synchronized remote detection stations. Our results show the impact of time-delay attacks on entangled pair detection rates, detection accuracy, and fidelity of the reconstructed Bell state. The effectiveness of our proposed countermeasure is demonstrated in simulation, showing that it maintains both the photon count rate and the fidelity at high levels, even when an eavesdropper introduces time delays in the quantum channel.
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In quantum communication experiments using entangled photon pairs far-distant measurement results are correlated on the sub-nanosecond level. For best performances the timing of the coincidence window and its width are critical. In contrast to lab experiments, where accurate timing could be adjusted easily by e.g. matched cable length, in distributed experiments a common clock more accurate than the coincidence time is requested by means of time stable synchronization channels or atom clocks synchronized by GPS. Synchronization of distant clocks is far from trivial. Efficient synchronization mechanisms are required to enable novel architectures like switched star shaped QKD-networks and facilitate quantum communication of a high number of potential users.
Quantum networks promise secure and efficient communication, but significant delays introduce critical limitations for long-distance quantum key distribution (QKD) and other quantum network applications. This paper presents a novel mechanism for precise delay compensation within quantum networks, leveraging quantum entanglement and interference. The core idea involves real-time measurement and correction of time delays using entangled photon pairs. We formally define the problem, propose a compensation strategy based on a feedback loop utilizing Bell state measurements and subsequent phase adjustments. The theoretical framework outlines the mathematical models and key equations governing the system, including those describing entanglement evolution, time delay propagation, and the measurement process. We explore the impact of various delay characteristics on the effectiveness of the compensation and discuss potential improvements and scaling challenges. The results demonstrate the feasibility of this approach and highlight its potential to significantly enhance the robustness and range of quantum networks.
Quantum networks intersect a paradigmatic shift in communication technologies, offering unprecedented capabilities for secure communication and distributed computation through the exploitation of quantum mechanical phenomena.These networks facilitate revolutionary and unlimited of possibility applications such as quantum key distribution (QKD), distributed quantum computing (DQC), quantum teleportation (QT), quantum clock synchronization (QCS), etc. -all fundamentally predicated on quantum entanglement as their operational cornerstone.Moreover, on the contrary with classical computer communication protocol, quantum networks have the fundamental no-cloning theorem in the quantum mechanic prohibits conventional signal amplification techniques, necessitating the development of quantum-native routing strategies that operate within these unique constraints.However, the practical realization of quantum networks until now still faces a crucial challenge: The reliability and efficient distribution of highfidelity entangled quantum states across long distances.Due to this distribution, the process faces intrinsic limitations arising from quantum decoherence, photonic loss in transmission channels, and the inherently probabilistic nature of entanglement generation protocols.In quantum communication, fidelity serves as a fundamental metric, representing the degree of similarity or correlation between the actual distributed entangled state and an ideal maximally entangled Bell pair.Fidelity is a crucial measure of the quality of quantum states in a network since it directly affects the reliability and effectiveness of quantum communication protocols.High fidelity ensures that the transmitted entangled states maintain their quantum properties, closely resembling the ideal Bell pair, and are thus suitable for performing secure and efficient quantum operations.Latency, on the other hand, refers to the total time delay involved in the entire process of entanglement establishment, from the initial creation of the entangled pairs to the final verification and confirmation of the entanglement quality.This includes several distinct components: the physical propagation delay, which accounts for the time it takes for quantum information to travel through the communication channel (such as optical fibers); the entanglement generation time, which involves the probabilistic creation of entangled states between quantum nodes; and the quantum memory storage time, which reflects the duration for which quantum states I