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In this paper we explore how recent technologies can improve the security of optical networks. In particular, we study how to use quantum key distribution (QKD) in common optical network infrastructures and propose a method to overcome its…

Quantum Physics · Physics 2013-04-16 David Elkouss , Jesus Martinez-Mateo , Alex Ciurana , Vicente Martin

Quantum key distribution (QKD) provides secure keys resistant to code-breaking quantum computers. As headed towards commercial application, it is crucial to guarantee the practical security of QKD systems. However, the difficulty of…

Quantum Physics · Physics 2018-05-14 Zhengyu Li , Yi-Chen Zhang , Hong Guo

Quantum key distribution (QKD) enables two remote parties to grow a shared key which they can use for unconditionally secure communication [1]. The applicable distance of a QKD protocol depends on the loss and the excess noise of the…

Quantum Physics · Physics 2012-10-08 Lars S. Madsen , Vladyslav C. Usenko , Mikael Lassen , Radim Filip , Ulrik L. Andersen

Quantum Key Distribution (QKD) in principle offers unconditional security based on the laws of physics. Continuous variable (CV) quantum key distribution has the potential for high-key-rate and low-cost implementations using standard…

Quantum Physics · Physics 2021-10-19 Chenyang Li , Li Qian , Hoi-Kwong Lo

There is a big gap between theory and practice in quantum key distribution (QKD) because real devices do not satisfy the assumptions required by the security proofs. Here, we close this gap by introducing a simple and practical…

Quantum Physics · Physics 2021-03-31 Álvaro Navarrete , Margarida Pereira , Marcos Curty , Kiyoshi Tamaki

We present a passive approach to the security analysis of quantum key distribution (QKD) with an untrusted source. A complete proof of its unconditional security is also presented. This scheme has significant advantages in real-life…

Quantum Physics · Physics 2015-05-13 Yi Zhao , Bing Qi , Hoi-Kwong Lo , Li Qian

Estimating correctly the quantum phase of a physical system is a central problem in quantum parameter estimation theory due to its wide range of applications from quantum metrology to cryptography. Ideally, the optimal quantum estimator is…

Quantum Physics · Physics 2021-06-09 Marco A. Rodríguez-García , Isaac Pérez Castillo , P. Barberis-Blostein

Measurement-device-independent quantum key distribution (MDI-QKD), which is immune to all detector side-channel attacks, is the most promising solution to the security issues in practical quantum key distribution systems. Though several…

Quantum Physics · Physics 2016-05-04 Zhiyuan Tang , Kejin Wei , Olinka Bedroya , Li Qian , Hoi-Kwong Lo

Continuous-variable quantum key distribution (CV-QKD) is a promising quantum-safe alternative to classical asymmetric cryptography that enables two authenticated parties to establish a shared secret over a potentially eavesdropped quantum…

Quantum Physics · Physics 2026-03-12 Jonas Berl , Utku Akin , Erdem Eray Cil , Laurent Schmalen , Tobias Fehenberger

We present a fiber-based continuous-variable quantum key distribution system. In the scheme, a quantum signal of two non-orthogonal weak optical coherent states is sent through a fiber-based quantum channel. The receiver simultaneously…

Optical communication is the standard for high-bandwidth information transfer in today's digital age. The increasing demand for bandwidth has led to the maturation of coherent transceivers that use phase- and amplitude-modulated optical…

Quantum Physics · Physics 2024-09-24 John Crossman , Spencer Dimitroff , Lukasz Cincio , Mohan Sarovar

Due to their compatibility to existing telecom technology, continuous variable (CV) weak coherent state protocols are promising candidates for a broad deployment of quantum key distribution (QKD) technology. We demonstrate how an existing…

Error estimation is an important step for error correction in quantum key distribution. Traditional error estimation methods require sacrificing a part of the sifted key, forcing a trade-off between the accuracy of error estimation and the…

We investigate quantum repeater protocols based upon atomic qubit-entanglement distribution through optical coherent-state communication. Various measurement schemes for an optical mode entangled with two spatially separated atomic qubits…

Quantum Physics · Physics 2010-12-14 Peter van Loock , Norbert Lütkenhaus , W. J. Munro , Kae Nemoto

The goal of quantum metrology is to improve measurements' sensitivities by harnessing quantum resources. Metrologists often aim to maximize the quantum Fisher information, which bounds the measurement setup's sensitivity. In studies of…

Quantum key distribution (QKD) is a provably secure way of generating a secret key, which can later be used for encoding and decoding information. In this paper we analyze the effects of an eavesdropper's variable-strength measurements on…

Quantum Physics · Physics 2025-10-01 Yuval Idan , Tal Gofman , Ziv Abelson , Isabelle Cestier , Elad Mentovich , Eliahu Cohen

We propose a quantum repeater for continuous variable (CV) quantum optical states. Our repeater relies on an error correction protocol for loss on CV states based on CV teleportation and entanglement distillation via noiseless linear…

Quantum Physics · Physics 2015-05-15 Josephine Dias , Tim Ralph

Due to its ability to tolerate high channel loss, decoy-state quantum key distribution (QKD) has been one of the main focuses within the QKD community. Notably, several experimental groups have demonstrated that it is secure and feasible…

Quantum Physics · Physics 2014-02-12 Charles Ci Wen Lim , Marcos Curty , Nino Walenta , Feihu Xu , Hugo Zbinden

An integrated error-correction scheme with high throughput, low frame errors rate (FER) and high reconciliation efficiency under low signal to noise ratio (SNR) is one of the major bottlenecks to realize high-performance and low-cost…

We investigate the security of continuous-variable (CV) quantum key distribution (QKD) using coherent states in the presence of quadrature excess noise. We consider an eavesdropping attack which uses a linear amplifier and beam splitter.…

Quantum Physics · Physics 2009-11-11 Ryo Namiki , Takuya Hirano