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Imperfect devices in commercial quantum key distribution systems open security loopholes that an eavesdropper may exploit. An example of one such imperfection is the wavelength dependent coupling ratio of the fiber beam splitter. Utilizing…

Optical fiber networks are part of important critical infrastructure and known to be prone to eavesdropping attacks. Hence cryptographic methods have to be used to protect communication. Quantum key distribution (QKD), at its core, offers…

Quantum Physics · Physics 2023-06-27 Alexandra Popp , Florian Sedlmeir , Birgit Stiller , Christoph Marquardt

In this study, we demonstrate the possibility to protect, with Quantum Key Distribution (QKD), a critical infrastructure as the fiber-based one used for time and frequency (TF) dissemination service. The proposed technique allows to…

Quantum key distributions (QKD) systems often rely on polarization of light for encoding, thus limiting the amount of information that can be sent per photon and placing tight bounds on the error that such a system can tolerate. Here we…

Superimposed temperature variations and dynamic strain applied through a 400 Hz acoustic signal on a 195 m single-mode fiber section are successfully measured using a coherent correlation optical time domain reflectometry as an…

Signal Processing · Electrical Eng. & Systems 2023-05-29 André Sandmann , Florian Azendorf , Michael Eiselt

How to remove detector side channel attacks has been a notoriously hard problem in quantum cryptography. Here, we propose a simple solution to this problem---*measurement* device independent quantum key distribution. It not only removes all…

Quantum Physics · Physics 2012-05-30 Hoi-Kwong Lo , Marcos Curty , Bing Qi

Two descriptions are introduced and analyzed for a reflectivity estimation and detection scheme that does not involve measurement of photons scattered by the target. One description, provided by the Hamiltonian dynamics of the full…

Quantum Physics · Physics 2024-08-23 T. J. Volkoff

In this paper, using the full security framework for continuous variable quantum key distribution (CV-QKD), we provide a composable security proof for the CV-QKD system in a realistic implementation. We take into account equipment losses…

Quantum Physics · Physics 2022-09-19 Roman Goncharov , Alexei D. Kiselev , Eduard Samsonov , Vladimir Egorov

Coherent-one-way (COW) quantum key distribution (QKD) held the promise of distributing secret keys over long distances with a simple experimental setup. Indeed, this scheme is currently used in commercial applications. Surprisingly,…

Quantum Physics · Physics 2021-09-22 Róbert Trényi , Marcos Curty

Avalanche photodiode based single photon detectors, as crucial and practical components, are widely used in quantum key distribution (QKD) systems. For effective detection, most of these SPDs are operated in the gated mode, in which the…

Quantum Physics · Physics 2019-09-25 Yong-Jun Qian , De-Yong He , Shuang Wang , Wei Chen , Zhen-Qiang Yin , Guang-Can Guo , Zheng-Fu Han

Quantum key distribution (QKD) gradually has become a crucial element of practical secure communication. In different scenarios, the security analysis of genuine QKD systems is complicated. A universal secret key rate calculation method,…

Quantum Physics · Physics 2021-09-13 Zehong Chang , Fumin Wang , Xiaoli Wang , Xiaofei Liu , Rongqian Wu , Yi lv , Pei Zhang

In this work, we study the security of coherent-state quantum key distribution with a strong reference pulse. The consideration is based on a powerful soft filtering attack and uses realistic parameters of the equipment. Our model allows us…

Twin-field (TF) quantum key distribution (QKD) fundamentally alters the rate-distance relationship of QKD, offering the scaling of a single-node quantum repeater. Although recent experiments have demonstrated the new opportunities for…

Twin-Field Quantum Key Distribution (TF-QKD) has become a leading protocol to bring quantum communications to the national scale. The protocol requires the establishment of a shared phase and frequency reference between distant parties,…

Despite the robust security guarantees of Quantum Key Distribution (QKD), its practical deployment is significantly challenged by the dynamic nature of quantum channels and the complexity of real-time parameter optimization. In this paper,…

Quantum Physics · Physics 2026-03-05 Noureldin Mohamed , Jawaher Kaldari , Saif Al-Kuwari

A novel Brillouin optical time-domain analysis (BOTDA) system is proposed using intensity-modulated optical orthogonal frequency division multiplexing probe signal and direct detection (IM-DD-OOFDM) without frequency sweep operation. The…

Instrumentation and Detectors · Physics 2017-02-13 Can Zhao , Ming Tang , Liang Wang , Hao Wu , Zhiyong Zhao , Yunli Dang , Jiadi Wu , Songnian Fu , Deming Liu , Perry Ping Shum

We present a composable security proof, valid against arbitrary attacks and including finite-size effects, for a high dimensional time-frequency quantum key distribution (TFQKD) protocol based upon spectrally entangled photons. Previous…

Quantum Physics · Physics 2016-09-30 Nathan Walk , Jonathan Barrett , Joshua Nunn

To plan a rapid response and minimize operational costs, passive optical network operators require to automatically detect and identify faults that may occur in the optical distribution network. In this work, we present DSP-Enhanced OTDR, a…

Signal Processing · Electrical Eng. & Systems 2018-01-22 Manuel P. Fernandez , Laureano A. Bulus Rossini , Juan Pablo Pascual , Pablo A. Costanzo Caso

Quantum key distribution (QKD) security fundamentally relies on the ability to distinguish genuine quantum correlations from classical eavesdropper simulations, yet existing certification methods lack rigorous statistical guarantees under…

Quantum Physics · Physics 2025-12-04 Davut Emre Tasar , Ceren Ocal Tasar

Distributing secret keys with information-theoretic security is arguably one of the most important achievements of the field of quantum information processing and communications. The rapid progress in this field has enabled quantum key…