Article
Multidisciplinary Sciences
Nitin Jain, Hou-Man Chin, Hossein Mani, Cosmo Lupo, Dino Solar Nikolic, Arne Kordts, Stefano Pirandola, Thomas Brochmann Pedersen, Matthias Kolb, Bernhard Omer, Christoph Pacher, Tobias Gehring, Ulrik L. Andersen
Summary: This paper introduces a continuous-variable quantum key distribution (CVQKD) protocol that can generate composable keys secure against collective attacks. By using Gaussian-modulated coherent states and improving the security proof and system operation, this CVQKD protocol overcomes the difficulty of key generation in existing protocols. This advance brings CVQKD implementations closer to their discrete-variable counterparts in terms of practicality, performance, and security.
NATURE COMMUNICATIONS
(2022)
Article
Physics, Multidisciplinary
Pu Wang, Yu Zhang, Zhenguo Lu, Xuyang Wang, Yongmin Li
Summary: Discrete-modulation continuous-variable (CV) quantum key distribution has the potential for large-scale deployment in secure quantum communication networks due to its low implementation complexity and compatibility with current coherent optical telecommunication. However, current protocols require large constellation sizes for comparable key rates to Gaussian modulation. This study demonstrates that a high key rate comparable to Gaussian modulation can be achieved using only ten or so coherent states through suitable key mapping and numerical convex optimization techniques.
NEW JOURNAL OF PHYSICS
(2023)
Article
Optics
T. I. A. N. Y. I. Wang, M. I. N. G. LI, X. U. Wang
Summary: This study investigates the impact of discretization on CV-QKD through experimental setups and modeling analysis, and proposes a data-filtering process to accurately estimate the quadrature fluctuation induced by discretized polar modulation. Numerical results show that under certain amplitude and phase resolutions, discretized polar modulation enables efficient transmission within a certain distance.
Article
Quantum Science & Technology
Adnan A. E. Hajomer, Nitin Jain, Hossein Mani, Hou-Man Chin, Ulrik L. Andersen, Tobias Gehring
Summary: This study proposes a CVQKD system without modulation leakage vulnerability, achieving state preparation and measurement using baseband modulation and an IQ modulator. The system can generate a composable secret key secure against collective attacks.
NPJ QUANTUM INFORMATION
(2022)
Article
Multidisciplinary Sciences
Takaya Matsuura, Kento Maeda, Toshihiko Sasaki, Masato Koashi
Summary: Continuous-variable quantum key distribution (CV-QKD) offers advantages in terms of cost and compatibility with wavelength division multiplexing compared to conventional discrete-variable QKD (DV-QKD), but lacks complete security proofs due to its continuous nature. By proposing a method to estimate fidelity via heterodyne measurements and proving the security of a binary phase modulated CV-QKD protocol, the authors address this gap in security proofs for CV-QKD in the finite-key-size regime. Exploiting the benefits of CV-QKD requires a full security proof against general attacks, which is achieved in this study for a protocol with a binary phase modulation.
NATURE COMMUNICATIONS
(2021)
Article
Quantum Science & Technology
Nitin Jain, Ivan Derkach, Hou-Man Chin, Radim Filip, Ulrik L. Andersen, Vladyslav C. Usenko, Tobias Gehring
Summary: This study identified a modulation leakage vulnerability in continuous-variable quantum key distribution systems, caused by inadequate suppression of certain sidebands during modulation. The leakage was found to impact the range of secret key obtainment and could potentially lead to security breaches, with additional trusted noise proving effective in countering this vulnerability.
QUANTUM SCIENCE AND TECHNOLOGY
(2021)
Article
Mathematics
Yiwu Zhu, Lei Mao, Hui Hu, Yijun Wang, Ying Guo
Summary: The article discusses the negative impact of analog-to-digital converter's finite sampling bandwidth on continuous-variable quantum key distribution, and proposes a method to enhance system security using an adaptive optics unit. The research demonstrates the feasibility of this method for CVQKD in realistic free-space environments through numerical simulations.
Article
Quantum Science & Technology
Florian Kanitschar, Ian George, Jie Lin, Twesh Upadhyaya, Norbert Lutkenhaus
Summary: Discrete-modulated continuous-variable quantum key distribution (DM CV-QKD) protocols are promising candidates for commercial quantum communication networks. This paper presents a finite-size security proof against independently and identically distributed collective attacks for a general DM CV-QKD protocol. The method addresses the issue of acceptance sets and allows for nonunique acceptance statistics.
Article
Quantum Science & Technology
Cosmo Lupo, Yingkai Ouyang
Summary: This study presents a theory to rigorously account for the experimental limitations of realistic heterodyne detection and obtains tight bounds on the key rates through semidefinite programming.
Article
Optics
Tianyi Wang, Ming LI, Xu Wang, Lei Hou
Summary: In experimental setups of CV-QKD, ideal Gaussian modulation degrades into discretized polar modulation (DPM), leading to an overestimation of excess noise. We show that the DPM-induced estimation bias depends solely on modulation resolutions and can be modeled as a quadratic function. By calibrating the estimated excess noise based on the quadratic bias model and analyzing the model residuals, we establish the upper bound of estimated excess noise and the lower bound of secret key rate. Simulation results demonstrate that the proposed calibration scheme can eliminate a 14.5% estimation bias, enhancing the efficiency and feasibility of DPM CV-QKD.
Article
Physics, Multidisciplinary
Leixin Wu, Yanyan Feng, Jian Zhou, Ronghua Shi, Jinjing Shi
Summary: This paper thoroughly analyzes the influence of gravity on quantum key distribution and presents an improved protocol for practical space communication.
EUROPEAN PHYSICAL JOURNAL PLUS
(2023)
Article
Quantum Science & Technology
Chenyang Li, Li Qian, Hoi-Kwong Lo
Summary: In this paper, simple security proofs for continuous variable quantum key distribution systems with intensity fluctuating sources are provided, with systems divided into two cases based on device assumptions in the source. The security is proven using the tagging idea, which is a main technique for discrete variable quantum key distribution, and the proofs are shown to be implementable without hardware adjustment for current systems, providing secure secret keys in finite-size scenarios.
NPJ QUANTUM INFORMATION
(2021)
Article
Optics
Yan Tian, Yu Zhang, Shuaishuai Liu, Pu Wang, Zhenguo Lu, Xuyang Wang, Yongmin Li
Summary: We demonstrate the successful implementation of a high-rate discretely modulated continuous-variable quantum key distribution system over 80 km standard single-mode fiber. By using well-designed digital signal processing algorithms, we effectively suppress the excess noise of the system. The achieved secret key rates are 49.02 Mbits/s, 11.86 Mbits/s, and 2.11 Mbits/s over 25 km, 50 km, and 80 km optical fiber, respectively, which are 67.4%, 70.0%, and 66.5% of the secret key rate performance of a Gaussian-modulated protocol.
Article
Optics
Jianqiang Liu, Yanxia Cao, Pu Wang, Shuaishuai Liu, Zhenguo Lu, Xuyang Wang, Yongmin Li
Summary: This study analyzes the impact of balanced homodyne detector (BHD) bandwidth and signal modulation patterns on the channel parameters estimation in continuous-variable quantum key distribution (CV-QKD) systems. It is found that insufficient BHD bandwidth leads to incorrect estimation of transmission loss and excess noise, significantly affecting the performance of CV-QKD systems. Additionally, an optimal signal repetition rate that maximizes the secure key rate is identified.
Article
Optics
Di Jin, Ying Guo, Yijun Wang, Yin Li, Duan Huang
Summary: The proposal introduces key-sifting algorithms for a CV-QKD protocol using machine learning and digital signal processing based on anomaly detection, showing improved feasibility in noisy environments. Experimental results over a 100-km fiber link confirm the utility of the algorithm in reducing excess noise, with potential application to other QKD protocols.
Article
Physics, Mathematical
Anthony Leverrier
JOURNAL OF MATHEMATICAL PHYSICS
(2018)
Editorial Material
Optics
Mohsen Razavi, Anthony Leverrier, Xiongfeng Ma, Bing Qi, Zhiliang Yuan
JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS
(2019)
Article
Computer Science, Hardware & Architecture
Omar Fawzi, Antoine Grospellier, Anthony Leverrier
Summary: The paper investigates the asymptotic scaling of space overhead required for fault-tolerant quantum computation, showing that the polylogarithmic factor in the standard threshold theorem is unnecessary. A fault-tolerant construction is proposed that only uses a constant factor more qubits than the ideal computation. This result challenges the traditional concatenated code approach and suggests using quantum error-correcting codes with a constant encoding rate.
COMMUNICATIONS OF THE ACM
(2021)
Article
Quantum Science & Technology
Daniele Dequal, Luis Trigo Vidarte, Victor Roman Rodriguez, Giuseppe Vallone, Paolo Villoresi, Anthony Leverrier, Eleni Diamanti
Summary: Establishing secure communication links at a global scale using quantum information science is challenging but achievable, as shown by recent landmark experiments. Continuous-variable encoding in a satellite-to-ground downlink configuration can lead to positive secret key rates, especially in low-Earth-orbit scenarios, with limitations potentially arising in higher orbits due to finite-size effects. Our analysis helps determine parameters for successful secret key exchange and can guide further experimental efforts in this direction.
NPJ QUANTUM INFORMATION
(2021)
Article
Quantum Science & Technology
Antoine Grospellier, Lucien Groues, Anirudh Krishna, Anthony Leverrier
Summary: This research introduces new hybrid decoders that combine the belief propagation algorithm with the small-set-flip (SSF) decoder to improve the decoding performance of quantum low-density parity-check (LDPC) codes. Numerical simulations show that the error threshold of these codes performs well under different conditions.
Article
Quantum Science & Technology
Aurelie Denys, Peter Brown, Anthony Leverrier
Summary: The study establishes an analytical lower bound for continuous-variable quantum key distribution, supporting efficient modulation schemes and proposing a solution suitable for large-scale deployment.
Article
Quantum Science & Technology
Anthony Leverrier, Simon Apers, Christophe Vuillot
Summary: This article introduces a variant of the three-dimensional hypergraph product code construction and explores the non-CSS quantum LDPC code and its related algebraic and combinatorial problems, aiming to find potential codes for self-correcting quantum memories.
Article
Quantum Science & Technology
Anthony Leverrier, Vivien Londe, Gilles Zemor
Summary: This study introduces a new family of quantum codes called hemicubic codes. These codes are obtained by associating qubits with the faces of the n-cube and stabilizer constraints with faces of dimension (p +/- 1). The resulting quantum codes display local testability and a decoding algorithm is developed to correct errors. The study also explores the extension of this code family by considering the quotient of the n-cube by arbitrary linear classical codes. These hemicubic codes have potential applications in quantum computing.
Proceedings Paper
Computer Science, Information Systems
Omar Fawzi, Lucien Groues, Anthony Leverrier
Summary: The decoder based on linear programming for quantum CSS codes has a different approach from previous definitions, but performs well in simulations, especially in hypergraph products, where it outperforms traditional methods.
2020 IEEE INFORMATION THEORY WORKSHOP (ITW)
(2021)
Article
Computer Science, Theory & Methods
Vivien Londe, Anthony Leverrier
QUANTUM INFORMATION & COMPUTATION
(2019)
Article
Optics
Shouvik Ghorai, Eleni Diamanti, Anthony Leverrier
Proceedings Paper
Computer Science, Theory & Methods
Omar Fawzi, Antoine Grospellier, Anthony Leverrier
STOC'18: PROCEEDINGS OF THE 50TH ANNUAL ACM SIGACT SYMPOSIUM ON THEORY OF COMPUTING
(2018)
Proceedings Paper
Computer Science, Theory & Methods
Omar Fawzi, Antoine Grospellier, Anthony Leverrier
2018 IEEE 59TH ANNUAL SYMPOSIUM ON FOUNDATIONS OF COMPUTER SCIENCE (FOCS)
(2018)
Proceedings Paper
Computer Science, Information Systems
Andre Chailloux, Anthony Leverrier
ADVANCES IN CRYPTOLOGY - EUROCRYPT 2017, PT III
(2017)
