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Any Quantum Key Distribution (QKD) protocol consists first of sequences of measurements that produce some correlation between classical data. We show that these correlation data must violate some Bell inequality in order to contain…

Quantum Physics · Physics 2009-11-11 Antonio Acin , Nicolas Gisin , Lluis Masanes

By carrying out measurements on entangled states, two parties can generate a secret key which is secure not only against an eavesdropper bound by the laws of quantum mechanics, but also against a hypothetical "post-quantum" eavesdroppers…

Quantum Physics · Physics 2007-10-22 Antonio Acin , Serge Massar , Stefano Pironio

The unconditional security of continuous-variable quantum key distribution is established for all schemes based on the estimation of the channel loss and excess noise. It is proved that, in the limit of large keys, Gaussian attacks are…

Quantum Physics · Physics 2010-12-15 Anthony Leverrier , Evgueni Karpov , Philippe Grangier , Nicolas J. Cerf

Brakerski et. al [BCM+18] introduced the model of cryptographic testing of a single untrusted quantum device and gave a protocol for certifiable randomness generation. We use the leakage resilience properties of the Learning With Errors…

Quantum Physics · Physics 2022-04-26 Urmila Mahadev , Umesh Vazirani , Thomas Vidick

We assess the security of a quantum key distribution protocol relying on the transmission of Gaussian-modulated coherent states and homodyne detection. This protocol is shown to be equivalent to a squeezed state protocol based on a CSS code…

Quantum Physics · Physics 2009-11-10 S. Iblisdir , G. Van Assche , N. J. Cerf

Numerical security proofs based on conic optimization are known to deliver optimal secret-key rates, but so far they have mostly assumed that the emitted states are fully characterized. In practice, this assumption is unrealistic, since…

Quantum Physics · Physics 2025-10-30 Margarida Pereira , Guillermo Currás-Lorenzo , Mateus Araújo

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

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

Ideal quantum key distribution (QKD) protocols call for a source that emits single photon signals, but the sources used in typical practical realizations emit weak coherent states instead. A weak coherent state may contain more than one…

Quantum Physics · Physics 2007-05-23 Hoi-Kwong Lo , John Preskill

High-quality, distributed quantum entanglement is the distinctive resource for quantum communication and forms the foundation for the unequalled level of security that can be assured in quantum key distribution. While the entanglement…

Quantum Physics · Physics 2024-08-23 Philipp Sohr , Sebastian Ecker , Lukas Bulla , Martin Bohmann , Rupert Ursin

Quantum key distribution provides secure keys with information-theoretic security ensured by the principle of quantum mechanics. The continuous-variable version of quantum key distribution using coherent states offers the advantages of its…

Quantum Physics · Physics 2024-07-09 Yichen Zhang , Yiming Bian , Zhengyu Li , Song Yu , Hong Guo

To achieve secure quantum key distribution, all imperfections in the source unit must be incorporated in a security proof and measured in the lab. Here we perform a proof-of-principle demonstration of the experimental techniques for…

Quantum Physics · Physics 2023-02-14 Anqi Huang , Akihiro Mizutani , Hoi-Kwong Lo , Vadim Makarov , Kiyoshi Tamaki

Quantum key distribution (QKD) protocols aim at allowing two parties to generate a secret shared key. While many QKD protocols have been proven unconditionally secure in theory, practical security analyses of experimental QKD…

Quantum Physics · Physics 2023-07-04 Michel Boyer , Gilles Brassard , Nicolas Godbout , Rotem Liss , Stéphane Virally

In network coding, we discuss the effect of sequential error injection on information leakage. We show that there is no improvement when the operations in the network are linear operations. However, when the operations in the network…

Information Theory · Computer Science 2018-09-27 Masahito Hayashi , Masaki Owari , Go Kato , Ning Cai

The lack of perfect randomness can cause significant problems in securing communication between two parties. McInnes and Pinkas proved that unconditionally secure encryption is impossible when the key is sampled from a weak random source.…

Quantum Physics · Physics 2012-02-20 J. Bouda , M. Pivoluska , M. Plesch

Fast secure random number generation is essential for high-speed encrypted communication, and is the backbone of information security. Generation of truly random numbers depends on the intrinsic randomness of the process used and is usually…

Quantum Physics · Physics 2019-05-15 Ben Haylock , Daniel Peace , Francesco Lenzini , Christian Weedbrook , Mirko Lobino

The rates of quantum cryptographic protocols are usually expressed in terms of a conditional entropy minimized over a certain set of quantum states. In particular, in the device-independent setting, the minimization is over all the quantum…

Quantum Physics · Physics 2022-10-05 Peter Brown , Hamza Fawzi , Omar Fawzi

In the decoy quantum key distribution, we show that a smaller decoy intensity gives a better key generation rate in the asymptotic setting when we employ only one decoy intensity and the vacuum pulse. In particular, the counting rate of…

Quantum Physics · Physics 2016-09-28 Masahito Hayashi

In recent years, several hacking attacks have broken the security of quantum cryptography implementations by exploiting the presence of losses and the ability of the eavesdropper to tune detection efficiencies. We present a simple attack of…

Quantum Physics · Physics 2016-01-28 Antonio Acín , Daniel Cavalcanti , Elsa Passaro , Stefano Pironio , Paul Skrzypczyk

A quantum key distribution protocol based on entanglement swapping is proposed. Through choosing particles by twos from the sequence and performing Bell measurements, two communicators can detect eavesdropping and obtain the secure key.…

Quantum Physics · Physics 2007-05-23 Fei Gao , Fenzhuo Guo , Qiaoyan Wen , Fuchen Zhu