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The security of quantum key distribution (QKD) relies on the Heisenberg uncertainty principle, with which legitimate users are able to estimate information leakage by monitoring the disturbance of the transmitted quantum signals. Normally,…

Quantum Physics · Physics 2017-04-03 Zhen Zhang , Xiao Yuan , Zhu Cao , Xiongfeng Ma

Parameter estimation is a critical step in continuous-variable quantum key distribution (CV-QKD), especially in the finite-size regime where worst-case confidence intervals can significantly reduce the achievable secret-key rate. We provide…

We propose a method for extracting an errorless secret key in a continuous-variable quantum key distribution protocol, which is based on Gaussian modulation of coherent states and homodyne detection. The crucial feature is an…

Quantum Physics · Physics 2009-11-13 Anthony Leverrier , Romain Alléaume , Joseph Boutros , Gilles Zémor , Philippe Grangier

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

Phase correlations are an under-explored vulnerability in QKD. Here, we present an experimental and simulated characterization of correlations arising from electro-optic phase encoding, over repetition rates up to the GHz level. To mitigate…

Quantum Physics · Physics 2025-09-24 Amita Gnanapandithan , Li Qian , Hoi-Kwong Lo

Error correction plays a major role in the reconciliation of continuous variable quantum key distribution (CV-QKD) and greatly affects the performance of the system. CV-QKD requires error correction codes of extremely low rates and high…

Information Theory · Computer Science 2021-07-14 Kadir Gümüs , Laurent Schmalen

In this paper, we investigate limitations imposed by sequential attacks on the performance of a differential-phase-shift (DPS) quantum key distribution (QKD) protocol with weak coherent pulses. Specifically, we analyze a sequential attack…

Quantum Physics · Physics 2008-10-12 Hipolito Gomez-Sousa , Marcos Curty

Differential-phase-shift (DPS) quantum key distribution (QKD) is one of the major QKD protocols that can be implemented with a simple setup using a laser source and a passive detection unit. Recently, an information-theoretic security proof…

Quantum Physics · Physics 2023-06-01 Akihiro Mizutani , Yuki Takeuchi , Kiyoshi Tamaki

High efficiency postprocessing of continuous-variable quantum key distribution system has a significant impact on the secret key rate and transmission distance of the system. Currently, the postprocessing mainly contains four steps in the…

Quantum Physics · Physics 2018-06-04 Xiangyu Wang , Yi-Chen Zhang , Song Yu , Hong Guo

We present a finite-size security proof of the decoy-state BB84 QKD protocol against coherent attacks, using entropic uncertainty relations, for imperfect detectors. We apply this result to the case of detectors with imperfectly…

Quantum Physics · Physics 2025-12-16 Devashish Tupkary , Shlok Nahar , Pulkit Sinha , Norbert Lütkenhaus

Quantum Key Distribution (QKD) offers unconditional security in principle. Many QKD protocols have been proposed and demonstrated to ensure secure communication between two authenticated users. Continuous variable (CV) QKD offers many…

In this work we present a comprehensive analysis of a post-selective attack on quantum key distribution protocols employing phase-encoded linearly independent coherent states (or similar alternatives). The attack relies on multimode…

Quantum Physics · Physics 2026-03-24 Andrei Gaidash , George Miroshnichenko , Anton Kozubov

In this paper, we consider continuous-variable quantum key distribution (QKD) protocols which use non-Gaussian modulations. These specific modulation schemes are compatible with very efficient error correction procedures, hence allowing the…

Quantum Physics · Physics 2015-03-17 Anthony Leverrier , Philippe Grangier

We introduce a robust scheme for long-distance continuous-variable (CV) measurement-device-independent (MDI) quantum key distribution (QKD) in which we employ post-selection between distant parties communicating through the medium of an…

The discrete variables (DV) time-frequency (TF) quantum key distribution (QKD) protocol is a BB84 like protocol, which utilizes time and frequency as complementary bases. As orthogonal modulations, pulse position modulation (PPM) and…

We analyze the performance of quantum key distribution (QKD) protocols that rely on discrete phase randomization (DPR). For many QKD protocols that rely on weak coherent pulses (WCPs), continuous phase randomization is assumed, which…

Quantum Physics · Physics 2026-03-05 Zhaohui Liu , Ahmed Lawey , Mohsen Razavi

Many quantum key distribution (QKD) protocols require random choice of measurement basis for each pulse or each train of pulses. In some QKD protocols, such as the Round-Robin Differential Phase Shift (RRDPS) QKD protocol, this requirement…

Quantum Physics · Physics 2016-04-18 Toshihiko Sasaki , Kiyoshi Tamaki , Masato Koashi

Quantum cryptography is now considered as a promising technology due to its promise of unconditional security. In recent years, rigorous work is being done for the experimental realization of quantum key distribution (QKD) protocols to…

Quantum Physics · Physics 2024-01-02 Satish Kumar , Priya Malpani , Britant , Sandeep Mishra , Anirban Pathak

Passive quantum key distribution (QKD) has been proposed for discrete variable protocols to eliminate side channels in the source. Unfortunately, the key rate of passive DV-QKD protocols suffers from sifting loss and additional quantum…

Quantum Physics · Physics 2022-12-06 Chenyang Li , Chengqiu Hu , Wenyuan Wang , Rong Wang , Hoi-Kwong Lo

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