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In realistic continuous variable quantum key distribution protocols, an eavesdropper may exploit the additional Gaussian noise generated during transmission to mask her presence. We present a theoretical framework for a post-selection based…

We introduce a constructive method to calculate the achievable secret key rate for a generic class of quantum key distribution protocols, when only a finite number n of signals is given. Our approach is applicable to all scenarios in which…

Quantum Physics · Physics 2007-05-23 Tim Meyer , Hermann Kampermann , Matthias Kleinmann , Dagmar Bruss

We propose an improved two-way continuous-variable quantum key distribution (CV QKD) protocol by adding proper random noise on the receiver's homodyne detection, the security of which is analysed against general collective attacks. The…

Quantum Physics · Physics 2013-05-07 Maozhu Sun , Xiang Peng , Hong Guo

We give an achievable secret key rate of a binary modulated continuous variable quantum key distribution schemes in the collective attack scenario considering quantum channels that impose arbitrary noise on the exchanged signals. Bob…

Quantum Physics · Physics 2009-11-13 Yi-Bo Zhao , Matthias Heid , Johannes Rigas , Norbert Lütkenhaus

We establish a lower bound on the asymptotic secret key rate of continuous-variable quantum key distribution with a discrete modulation of coherent states. The bound is valid against collective attacks and is obtained by formulating the…

Quantum Physics · Physics 2019-06-27 Shouvik Ghorai , Philippe Grangier , Eleni Diamanti , Anthony Leverrier

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

A quantum key distribution network enables pairs of users to generate independent secret keys by leveraging the principles of quantum physics. For end-to-end secure communication, a user pair's secret key must remain secure against any…

Quantum Physics · Physics 2026-02-26 Yiming Bian , Yichen Zhang , Song Yu , Zhengyu Li , Hong Guo

Continuous-variable quantum key distribution (CV-QKD) is realized with coherent detection and is therefore very suitable for a cost-efficient implementation. The major challenge in CV-QKD is mitigation of laser phase noise at a signal to…

Quantum Physics · Physics 2019-08-13 Sebastian Kleis , Max Rueckmann , Christian G. Schaeffer

We develop a theory for long-distance quantum key distribution based on concatenated entanglement swapping using parametric down-conversion sources and show numerical results of our model. The model incorporates practical resources…

Quantum Physics · Physics 2016-02-09 Aeysha Khalique , Barry C. Sanders

We study quantum communication in the presence of adversarial noise. In this setting, communicating with perfect fidelity requires using a quantum code of bounded minimum distance, for which the best known rates are given by the quantum…

Quantum Physics · Physics 2008-01-28 Debbie Leung , Graeme Smith

Information reconciliation is crucial for continuous-variable quantum key distribution (CV-QKD) because its performance affects the secret key rate and maximal secure transmission distance. Fixed-rate error correction codes limit the…

Quantum Physics · Physics 2019-11-11 Chao Zhou , Xiangyu Wang , Yi-Chen Zhang , Zhiguo Zhang , Song Yu , Hong Guo

We report a continuous variable key distribution system that achieves a final secure key rate of 3.45 kb/sec over a distance of 24.2 km of optical fiber. The protocol uses discrete signaling and post-selection to improve reconciliation…

Quantum Physics · Physics 2009-10-07 Quyen Dinh Xuan , Zheshen Zhang , Paul L. Voss

The two-way capacities of quantum channels determine the ultimate entanglement and secret-key distribution rates achievable by two distant parties that are connected by a noisy transmission line, in absence of quantum repeaters. Since…

Quantum Physics · Physics 2025-01-27 Francesco Anna Mele , Ludovico Lami , Vittorio Giovannetti

Quantum key distribution (QKD) allows two distant parties to share encryption keys with security based on physical laws. Experimentally, it has been implemented with optical means, achieving key rates of 1.26 Megabit/s over 50 kilometres…

Quantum Physics · Physics 2018-11-19 Marco Lucamarini , Zhiliang Yuan , James F. Dynes , Andrew J. Shields

We demonstrate that secure quantum key distribution systems based on continuous variables implementations can operate beyond the apparent 3 dB loss limit that is implied by the beam splitting attack . The loss limit was established for…

Quantum Physics · Physics 2009-11-07 Ch. Silberhorn , T. C. Ralph , N. Lütkenhaus , G. Leuchs

Modern security proofs of quantum key distribution (QKD) must take finite-size effects and composable aspects into consideration. This is also the case for continuous-variable (CV) protocols which are based on the transmission and detection…

Quantum Physics · Physics 2025-11-27 Stefano Pirandola , Panagiotis Papanastasiou

Continuous variable quantum key distribution bears the promise of simple quantum key distribution directly compatible with commercial off the shelf equipment. However, for a long time its performance was hindered by the absence of good…

Quantum Physics · Physics 2025-06-18 Jesus Martinez-Mateo , David Elkouss

We expand the recently discussed continuous-variable quantum key distribution scheme of Heid and Luetkenhaus (2006) to qudits with a lossy but noiseless quantum channel. Postselection methods are used. Secret key rates are calculated in the…

Quantum Physics · Physics 2009-03-12 Ulrich Seyfarth

A continuous-variable quantum key distribution protocol based on squeezed states and heterodyne detection is introduced and shown to attain higher secret key rates over a noisy line than any other one-way Gaussian protocol. This increased…

Quantum Physics · Physics 2009-11-13 Raul Garcia-Patron , Nicolas J. Cerf

In quantum key distribution implementations, each session is typically chosen long enough so that the secret key rate approaches its asymptotic limit. However, this choice may be constrained by the physical scenario, as in the perspective…

Quantum Physics · Physics 2014-06-18 Davide Bacco , Matteo Canale , Nicola Laurenti , Giuseppe Vallone , Paolo Villoresi