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We numerically analyse quantum survival probability fluctuations in an open, classically chaotic system. In a quasi-classical regime, and in the presence of classical mixed phase space, such fluctuations are believed to exhibit a fractal…

Condensed Matter · Physics 2009-11-07 Giuliano Benenti , Giulio Casati , Italo Guarneri , Marcello Terraneo

In pursuit of a global quantum key distribution (QKD) network, a service based on untrusted nodes on geostationary satellites could offer wide coverage, continuous operation, and enhanced security compared to the trusted node alternative.…

We study covert communication and covert secret key generation with positive rates over quantum state-dependent channels. Specifically, we consider fully quantum state-dependent channels when the transmitter shares an entangled state with…

Information Theory · Computer Science 2025-12-01 Hassan ZivariFard , Rémi A. Chou , Xiaodong Wang

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

The goal of this paper is to extend the framework of finite size analysis recently developed for quantum key distribution to continuous-variable protocols. We do not solve this problem completely here, and we mainly consider the finite size…

Quantum Physics · Physics 2010-06-29 Anthony Leverrier , Frédéric Grosshans , Philippe Grangier

This work presents a study of continuous-variable quantum key distribution (CV-QKD) protocols over fast-fading channels, typically found in free-space communication links. Two eavesdropping models are considered to evaluate their security…

Quantum Physics · Physics 2025-11-18 Miguel Castillo-Celeita , Matteo Schiavon

Satellite quantum communications are emerging within the panorama of quantum technologies as a more effective strategy to distribute completely-secure keys at very long distances, therefore playing an important role in the architecture of a…

Quantum Physics · Physics 2021-05-20 Stefano Pirandola

In this paper, we consider continuous-variable quantum key distribution with a discrete modulation, either binary or quaternary. We establish the security of these protocols against the class of collective attacks that induce a linear…

Quantum Physics · Physics 2015-03-13 Anthony Leverrier , Philippe Grangier

Digital signal processing technology has paved the way for the realization of high-speed continuous-variable quantum key distribution systems. However, existing security proofs are limited to static digital signal processing algorithms,…

Quantum Physics · Physics 2026-02-06 Lu Fan , Zhengyu Li , Sheng Liu , Xuesong Xu , Tianyu Zhang , Jiale Mi , Dong Wang , Dechao Zhang , Han Li , Song Yu , Yichen Zhang

Quantum key distribution (QKD) allows for communication with security guaranteed by quantum theory. The main theoretical problem in QKD is to calculate the secret key rate for a given protocol. Analytical formulas are known for protocols…

Quantum Physics · Physics 2016-05-24 Patrick J. Coles , Eric M. Metodiev , Norbert Lütkenhaus

We provide a rigorous treatment of the entanglement properties of two-mode Gaussian states in atmospheric channels by deriving and analyzing the input-output relations for the corresponding entanglement test. A key feature of such turbulent…

Quantum Physics · Physics 2016-07-27 M. Bohmann , A. A. Semenov , J. Sperling , W. Vogel

Measurement-device-independent quantum key distribution with a finite number of decoy states is analyzed under finite-data-size assumption. By accounting for statistical fluctuations in parameter estimation, we investigate vacuum+weak- and…

Quantum Physics · Physics 2012-11-14 Xiongfeng Ma , Chi-Hang Fred Fung , Mohsen Razavi

Quantum communication has been successfully implemented in optical fibres and through free-space [1-3]. Fibre systems, though capable of fast key rates and low quantum bit error rates (QBERs), are impractical in communicating with…

Channel capacities quantify the optimal rates of sending information reliably over noisy channels. Usually, the study of capacities assumes that the circuits which sender and receiver use for encoding and decoding consist of perfectly…

Quantum Physics · Physics 2024-04-15 Paula Belzig , Matthias Christandl , Alexander Müller-Hermes

Quantum Key Distribution (QKD) is a key exchange protocol which is implemented over free space optical links and optical fiber cable. When direct communication is not possible, QKD is performed over fiber cables, but the imperfections in…

Quantum Physics · Physics 2019-03-14 Vishal Sharma , Subhashish Banerjee

By exploiting multipath fading channels as a source of common randomness, physical layer (PHY) based key generation protocols allow two terminals with correlated observations to generate secret keys with information-theoretical security.…

Cryptography and Security · Computer Science 2011-09-08 Qian Wang , Kaihe Xu , Kui Ren

Quantum key distribution (QKD) allows for secure communications safe against attacks by quantum computers. QKD protocols are performed by sending a sizeable, but finite, number of quantum signals between the distant parties involved. Many…

Quantum Physics · Physics 2021-01-05 Darius Bunandar , Luke C. G. Govia , Hari Krovi , Dirk R. Englund

In this letter, we analyze the secrecy outage probability (SOP) over fluctuating two-ray fading channels but with a different definition from the one adopted in [5]. Following the new defined SOP, we derive an analytical closed-form…

Signal Processing · Electrical Eng. & Systems 2019-05-30 Hui Zhao , Liang Yang , Gaofeng Pan , Mohamed-Slim Alouini

Statistical fluctuation problems are faced by all quantum key distribution (QKD) protocols under finite-key condition. Most of the current statistical fluctuation analysis methods work based on independent random samples, however, the…

Quantum Physics · Physics 2016-01-06 Hongxin Li , Haodong Jiang , Ming Gao , Zhi Ma , Chuangui Ma , Wei Wang

A distributed estimation scheme where the sensors transmit with constant modulus signals over a multiple access channel is considered. The proposed estimator is shown to be strongly consistent for any sensing noise distribution in the…

Information Theory · Computer Science 2015-05-14 Cihan Tepedelenlioglu , Adarsh B. Narasimhamurthy