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We propose the use of intra-particle entanglement to enhance the security of a practical implementation of the Bennett-Brassard-1984 (BB84) quantum key distribution scheme. Intra-particle entanglement is an attractive resource since it can…

Quantum Physics · Physics 2013-04-24 S. Adhikari , Dipankar Home , A. S. Majumdar , A. K. Pan , Akshata Shenoy H. , R. Srikanth

We propose a simplified measurement scheme for a Gaussian modulated coherent state (GMCS) protocol for continuous variable quantum key distribution (CV-QKD), utilizing homodyne detection without quadrature switching. The reference frame of…

Quantum Physics · Physics 2025-11-13 Vinod N. Rao , Emma Tien Hwai Medlock , Timothy Spiller , Rupesh Kumar

We prove the unconditional security of a quantum key distribution protocol in which bit values are encoded in the phase of a weak coherent-state pulse relative to a strong reference pulse. In contrast to implementations in which a weak…

Quantum Physics · Physics 2009-11-10 Masato Koashi

The decoy-state method in quantum key distribution (QKD) is a popular technique to approximately achieve the performance of ideal single-photon sources by means of simpler and practical laser sources. In high-speed decoy-state QKD systems,…

Quantum Physics · Physics 2025-04-01 Víctor Zapatero , Álvaro Navarrete , Kiyoshi Tamaki , Marcos Curty

Decoy state method closes source security loophole in quantum key distribution (QKD) using laser source. In this method, accurate estimates of the detection rates of vacuum and single photon events plus the error rate of single photon…

Quantum Physics · Physics 2018-04-11 H. F. Chau

We propose a novel scheme for continuous variable quantum key distribution(CV-QKD) using the subcarrier multiplexing technique which was employed in microwave photonics. This scheme allows to distribute N channels independent Gaussian…

Quantum Physics · Physics 2014-02-19 Jian Fang , Peng Huang , Guihua Zeng

Quantum key distribution (QKD) using entangled photon sources (EPS) is a cornerstone of secure communication. Despite rapid advances in QKD, conventional protocols still employ beam splitters (BSs) for passive random basis selection.…

Quantum Physics · Physics 2026-03-02 Ayan Kumar Nai , Gopal Prasad Sahu , Rutuj Gharate , C. M. Chandrashekar , G. K. Samanta

Quantum conditional entropies play a fundamental role in quantum information theory. In quantum key distribution, they are exploited to obtain reliable lower bounds on the secret-key rates in the finite-size regime, against collective…

Quantum Physics · Physics 2026-03-05 Gabriele Staffieri , Giovanni Scala , Cosmo Lupo

We analyze theoretically performance of four-state quantum key distribution protocols implemented with a realistic heralded single-photon source. The analysis assumes a noisy model for the detector heralding generation of individual photons…

Quantum Physics · Physics 2013-07-04 Mikolaj Lasota , Rafal Demkowicz-Dobrzanski , Konrad Banaszek

Quantum key distribution using three states in equiangular configuration combines a security threshold comparable with the one of the Bennett-Brassard 1984 protocol and a quantum bit error rate (QBER) estimation that does not need to reveal…

Quantum Physics · Physics 2016-08-02 Matteo Schiavon , Giuseppe Vallone , Paolo Villoresi

The security proofs of continuous-variable quantum key distribution are based on the assumptions that the eavesdropper can neither act on the local oscillator nor control Bob's beam splitter. These assumptions may be invalid in practice due…

High-speed quantum key distribution (QKD) systems have achieved repetition frequencies above gigahertz through advanced technologies and devices, laying an important foundation for the deployment of high-key-rate QKD system. Although these…

Quantum Physics · Physics 2026-04-23 Jialei Su , Qingquan Peng , Jia-lin Chen , Feng-yu Lu , Zihao Chen , Junxuan Liu , De-yong He , Shuang Wang , Anqi Huang

This is a study of the security of the Coherent One-Way (COW) protocol for quantum cryptography, proposed recently as a simple and fast experimental scheme. In the zero-error regime, the eavesdropper Eve can only take advantage of the…

Quantum Physics · Physics 2008-02-05 Cyril Branciard , Nicolas Gisin , Norbert Lutkenhaus , Valerio Scarani

Continuous-variable quantum key distribution protocol using coherent states and heterodyne detection, called No-Switching protocol, is widely used in practical systems due to the simple experimental setup without basis switching and easy…

Quantum Physics · Physics 2024-02-02 Jiale Mi , Yiming Bian , Lu Fan , Song Yu , Yichen Zhang

In this Paper, we investigate the security of Zhang, Li and Guo quantum key distribution via quantum encryption protocol [$\text{Phys. Rev. A} \textbf{64}, 24302 (2001)$] and show that it is not secure against some of Eve's attacks and with…

Quantum Physics · Physics 2007-05-23 A. Fahmi

Quantum key distribution (QKD) based on coherent states is well known for its implementation simplicity, but it suffers from loss-dependent attacks based on optimal unambiguous state discrimination. Crucially, previous research has…

Quantum Physics · Physics 2020-06-05 Li Liu , Yukun Wang , Emilien Lavie , Arno Ricou , Chao Wang , Fen Zhuo Guo , Charles Ci Wen Lim

We investigate a decoy-state quantum key distribution (QKD) scheme with a sub-Poissonian single-photon source, which is generated on demand by scattering a coherent state off a two-level system in a one-dimensional waveguide. We show that,…

Quantum Physics · Physics 2013-02-22 Huaixiu Zheng , Daniel J. Gauthier , Harold U. Baranger

Quantum key distribution (QKD) which enables information-theoretically security is now heading towards quantum secure networks. It requires high-performance and cost-effective protocols while increasing the number of users. Unfortunately,…

Quantum Physics · Physics 2023-02-07 Yiming Bian , Yi-Chen Zhang , Chao Zhou , Song Yu , Zhengyu Li , Hong Guo

We introduce a protocol for quantum secret sharing based on reusable entangled states. The entangled state between the sender and the receiver acts only as a carrier to which data bits are entangled by the sender and disentangled from it by…

Quantum Physics · Physics 2016-09-08 Saber Bagherinezhad , Vahid Karimipour

In this paper, a new decoy-state scheme for quantum key distribution with parametric down-conversion source is proposed. We use both three-intensity decoy states and their triggered and nontriggered components to estimate the fraction of…

Quantum Physics · Physics 2009-11-13 Qin Wang , Xiang-Bin Wang , Gunnar Bjork , Anders Karlsson