Article
Optics
Junsang Oh, Jeongsik Cho, June-Koo Kevin Rhee
Summary: A novel heterodyne detection scheme for continuous-variable quantum key distribution (CVQKD) is proposed in this study, which measures both quadrature components of a quantum signal encoded in optical phase space. The proposed method achieves identical performance to conventional heterodyne detection with only a single homodyne detection system using time division. Additionally, a Faraday-Michelson interferometer is utilized in our method to make it independent of polarization drift and eliminate the need for dynamic polarization control. Experimental results demonstrate that our method, using the Gaussian-modulated coherent-states (GMCS) protocol, achieves an expected secret key rate of up to 0.187 Mbps over a 20.06 km optical fiber channel.
Article
Optics
Mi Zou, Yingqiu Mao, Teng-Yun Chen
Summary: This study proposes a rigorous calibration method for homodyne detection efficiency, aiming to establish a trusted noise-free detection model for continuous-variable quantum key distribution. The experimental results demonstrate that overestimating the detection efficiency leads to underestimation of modulation variance and excess noise, which poses security vulnerabilities.
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
Physics, Multidisciplinary
Yi Zheng, Haobin Shi, Wei Pan, Quantao Wang, Jiahui Mao
Summary: The paper introduces a new quantum hacking attack on an integrated silicon photonic continuous-variable quantum key distribution (CVQKD) system, known as a power analysis attack. This attack involves analyzing the power from the integrated electrical control circuit in state preparation with the help of machine learning, and the simulation results show that an increase in attack accuracy leads to decreased secret key information.
Article
Optics
Zikang Su, Jintao Wang, Dajian Cai, Xiaojie Guo, Dawei Wang, Zhaohui Li
Summary: We propose and experimentally demonstrate a phase-sensitive continuous variable quantum key distribution system with improved secure key rate, utilizing multimode coherent states, phase-conjugated subcarrier modulation, and phase-sensitive detection. The experimental results confirm the higher secure key rate and better excess noise tolerance of the new scheme compared to the typical implementation of GG02.
PHOTONICS RESEARCH
(2023)
Article
Multidisciplinary Sciences
Mariana F. Ramos, Armando N. Pinto, Nuno A. Silva
Summary: This study proposes a implementation method of discrete-variable quantum key distribution (DV-QKD) that combines phase modulators and conjugate homodyne detection scheme, enabling the deployment of high-speed QKD systems. The system relies on a detection threshold and a time-multiplexed pilot tone-quantum signal architecture, optimizing system performance and compensating for polarization drift.
SCIENTIFIC REPORTS
(2022)
Article
Physics, Multidisciplinary
Yanxiang Jia, Xuyang Wang, Xiao Hu, Xin Hua, Yu Zhang, Xubo Guo, Shengxiang Zhang, Xi Xiao, Shaohua Yu, Jun Zou, Yongmin Li
Summary: We have designed and experimentally demonstrated a silicon photonics-integrated time-domain balanced homodyne detector with excellent common mode rejection ratio. It has been successfully used in quantum tomography experiments and continuous-variable quantum key distribution systems.
NEW JOURNAL OF PHYSICS
(2023)
Article
Physics, Multidisciplinary
Ryo Namiki
Summary: In this study, we analyze the security against collective attacks for a homodyne-based continuous-variable quantum key distribution protocol using binary coherent states and postselection. We derive a lower bound of the secret key rate in an asymptotic scenario and numerically optimize it for the case of a symmetric Gaussian channel.
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN
(2023)
Article
Quantum Science & Technology
Polina Acheva, Konstantin Zaitsev, Vladimir Zavodilenko, Anton Losev, Anqi Huang, Vadim Makarov
Summary: An automated testbench has been developed to detect vulnerabilities in single-photon detectors in quantum key distribution when subjected to tailored bright illumination attacks. The testbench successfully identifies the controllability of a free-running detector in continuous-blinding regime and reveals the excessive photocurrent in a quantum regime, indicating the attack. A manually performed pulsed blinding attack is found to be missed by the countermeasure in a wide range of blinding pulse durations and powers, allowing the eavesdropping of the key. Recommendations for improvements in both the testbench and countermeasure are provided.
EPJ QUANTUM TECHNOLOGY
(2023)
Article
Physics, Multidisciplinary
Shengjie Xu, Yin Li, Yun Mao, Ying Guo
Summary: This paper suggests a countermeasure approach to resist saturation attacks in continuous-variable quantum key distribution (CVQKD) by embedding an adjustable optical filter (AOF) in the system. Numerical simulations demonstrate the positive effects of this approach on the system performance and the ability to trace back eavesdropped information.
Article
Quantum Science & Technology
Subhankar Bera, Shashank Gupta, A. S. Majumdar
Summary: We uniformly generate random states of various ranks and study their performance in entanglement-based quantum key distribution. We analyze the efficacy of random two-qubit states in device-independent QKD and observe that the number of entangled and Bell-nonlocal states decreases as rank increases. The decrease in the secure key rate is more pronounced with the increase in rank. We find that pure state and Werner state provide the upper and lower bound on the minimum secure key rate of all mixed two-qubit states with the same magnitude of entanglement under general and optimal collective attack strategies.
QUANTUM INFORMATION PROCESSING
(2023)
Article
Optics
Jaehak Lee, Jiyong Park, Jaewan Kim, M. S. Kim, Hyunchul Nha
Summary: Homodyne measurement is a crucial tool for addressing continuous variables in bosonic quantum systems. However, the use of a strong coherent local oscillator is not readily available for massive quantum systems like a Bose-Einstein condensate, making it necessary to establish a practical framework that includes the effects of nonideal local oscillators. We develop entanglement criteria beyond a Gaussian regime for realistic homodyne measurement, which do not require assumptions on the state of local oscillators.
Article
Physics, Multidisciplinary
Shihai Sun, Feihu Xu
Summary: This study provides a comprehensive security analysis considering both source and detection imperfections, evaluating the performance of a QKD system with imperfections. It represents an important step toward practical security of QKD with realistic devices.
NEW JOURNAL OF PHYSICS
(2021)
Article
Quantum Science & Technology
Shyam R. Sihare
Summary: The research paper presents a new approach to multi-party quantum key distribution using variational quantum eigensolvers. It aims to establish secure communication among multiple parties in a quantum network. The paper outlines a comprehensive framework and provides mathematical formulations and experimental designs.
ADVANCED QUANTUM TECHNOLOGIES
(2023)
Article
Quantum Science & Technology
G. S. Castro, R. Ramos
Summary: In quantum key distribution protocols, eavesdropper activities can be detected by analyzing the randomness of the bit sequence obtained by Bob after a slight modification of the BB84 QKD protocol. The research suggests that using disentropy to measure the randomness of signals can enhance security in QKD setups. A second eavesdropping detection strategy is proposed to further improve the security of QKD systems by distinguishing between errors caused by eavesdroppers and those by imperfections in the optical channel and optoelectronic devices.
QUANTUM INFORMATION PROCESSING
(2022)
Article
Optics
Ze-Hao Wang, Shuang Wang, Guan-Jie Fan-Yuan, Feng-Yu Lu, Zhen-Qiang Yin, Wei Chen, De-Yong He, Guang-Can Guo, Zheng-Fu Han
Summary: Measurement-device-independent quantum key distribution (MDI-QKD) is a crucial protocol in quantum communication, and considering the afterpulse effect can significantly improve the key rate, as demonstrated by the developed afterpulse-compatible MDI-QKD model.
Article
Optics
Xing Lin, Rong Wang, Shuang Wang, Zhen-Qiang Yin, Wei Chen, De-Yong He, Zheng Zhou, Guang-can Guo, Zhen-fu Han
Summary: This article proposes a unified model for imperfect measurements in SI-QRNG and provides a tight rate bound based on the uncertainty relation for smooth entropies. The performance is evaluated with large device imperfections, and the randomness rate in our model can approach a similar order of magnitude of the rate upper bound in common discrete variable QRNGs.
Article
Physics, Multidisciplinary
Xing Lin, Rong Wang, Shuang Wang, Zhen-Qiang Yin, Wei Chen, Guang-Can Guo, Zheng-Fu Han
Summary: Generating random numbers is important in scientific applications. Quantum devices can generate true random numbers based on quantum mechanics. In order to address the deviation between existing random number generation models and real-world devices, we propose a quantum random number generation protocol and demonstrate it experimentally. Our protocol makes no assumptions about the source and only requires certain reasonable assumptions about trusted two-dimensional measurements. We achieve a randomness generation rate of over 1 Mbps with a universal composable security parameter of 10(-10).
PHYSICAL REVIEW LETTERS
(2022)
Article
Optics
Feng-Yu Lu, Ze-Hao Wang, Zhen-Qiang Yin, Shuang Wang, Rong Wang, Guan-Jie Fan-Yuan, Xiao-Juan Huang, De-Yong He, Wei Chen, Zheng Zhou, Guang-Can Guo, Zheng-Fu Han
Summary: Measurement-device-independent quantum key distribution (MDIQKD) is a revolutionary protocol that is immune to attacks on the detection side. This work presents a MDIQKD protocol that requires less knowledge of the encoding system to combat modulation errors and fluctuations, and experimental results show high performance and good security for practical applications.
Article
Optics
Guan-Jie Fan-Yuan, Feng-Yu Lu, Shuang Wang, Zhen-Qiang Yin, De-Yong He, Wei Chen, Zheng Zhou, Ze-Hao Wang, Jun Teng, Guang-Can Guo, Zheng-Fu Han
Summary: This study proposes an MDI-QKD networking scheme that is robust against environmental disturbance and adaptable to multi-user access. It allows multiple users to generate keys simultaneously in a multi-user scenario.
Article
Optics
Peng Ye, Wei Chen, Ze-Hao Wang, Guo-Wei Zhang, Yu-Yang Ding, Guan-Zhong Huang, Zhen-Qiang Yin, Shuang Wang, De-Yong He, Wen Liu, Guang-Can Guo, Zheng-Fu Han
Summary: This article proposes an on-chip transmittance-invariant phase modulator (TIPM) to solve the non-ideal quantum state preparation issue in chip-based quantum key distribution systems. Simulated and experimental results show that TIPM can eliminate the correlation between phase, intensity, and polarization of quantum states caused by phase-dependent loss. TIPM also has a significant fabrication mismatch tolerance and can be applied to multi-material platforms, improving the practical security and performance of chip-based QKD systems.
Article
Computer Science, Information Systems
Guo-Wei Zhang, Wei Chen, Guan-Jie Fan-Yuan, Li Zhang, Fang-Xiang Wang, Shuang Wang, Zhen-Qiang Yin, De-Yong He, Wen Liu, Jun-Ming An, Guang-Can Guo, Zheng-Fu Han
Summary: A polarization-insensitive time-bin decoder chip for self-stabilizing QKD system is developed and verified, which shows its feasibility in experimental tests.
SCIENCE CHINA-INFORMATION SCIENCES
(2022)
Editorial Material
Optics
Shuang Wang
Summary: Quantum key distribution is a proven secure method for private key distribution, enabling the practical implementation of information retrieval that protects both user privacy and database security.
LIGHT-SCIENCE & APPLICATIONS
(2022)
Article
Physics, Multidisciplinary
Rui-Qiang Wang, Zhen-Qiang Yin, Xiao-Hang Jin, Rong Wang, Shuang Wang, Wei Chen, Guang-Can Guo, Zheng-Fu Han
Summary: Quantum key distribution (QKD) allows secure sharing of keys between remote parties. Continuous phase randomization, commonly assumed in QKD protocols, is challenged in experiments. In this study, we propose a technique based on conjugate measurement and quantum state distinguishment to analyze the security of a QKD protocol with discrete-phase randomization. Our results show that TF-QKD with a reasonable number of discrete random phases can achieve satisfactory performance, but finite-size effects become more notable. This method is also applicable to other QKD protocols.
Article
Physics, Applied
Yao Zhou, Zhen-Qiang Yin, Rui-Qiang Wang, Shuang Wang, Wei Chen, Guang-Can Guo, Zheng-Fu Han
Summary: This article proposes a TF QKD protocol with partial phase postselection, which maintains the advantage of high key rate while improving performance. Numerical simulations confirm the potential advantages of this protocol in terms of key rate and achievable distance.
PHYSICAL REVIEW APPLIED
(2022)
Article
Physics, Applied
Xiao-Hai Zhan, Zhen-Qiu Zhong, Shuang Wang, Zhen-Qiang Yin, Wei Chen, De-Yong He, Guang-Can Guo, Zheng-Fu Han
Summary: This article proposes a new approach to quantitatively evaluate the role of unique features in MDI QKD by decomposing the spectral entangled state, thereby improving the secure key rate.
PHYSICAL REVIEW APPLIED
(2023)
Article
Optics
Xiao-Juan Huang, Feng-Yu Lu, Shuang Wang, Zhen-Qiang Yin, Ze-Hao Wang, Wei Chen, De-Yong He, Guan-Jie Fan-Yuan, Guang-Can Guo, Zheng-Fu Han
Summary: This article presents a dependency model for quantum-key distribution (QKD) systems, which improves the optimization accuracy and guides users on choosing suitable dead time parameters by considering the dead time and afterpulse issues of single-photon avalanche diodes (SPADs).
Article
Optics
Zhen-Qiu Zhong, Shuang Wang, Xiao-Hai Zhan, Zhen-Qiang Yin, Wei Chen, Guang-Can Guo, Zheng-Fu Han
Summary: This paper analyzes the correlation between the photon-number distribution and the joint spectral distribution in entanglement-based quantum key distribution (EB-QKD) and presents a general model that can be used to calculate the secure key rate for both pulse-pumped and continuous-wave (cw) pumped systems. The existing models, which consider the photon-number distribution of pulse-pumped entanglement sources as thermal, lead to an overestimation of the secure key rate due to the neglect of spectral modes.
Article
Optics
Lu Fengyu, Yin Zhenqiang, Wang Shang, Wang Zehao, Chen Wei, Guo Guangcan, Han Zhenfu
Summary: The uncharacterized-source MDI-QKD is a protocol that can generate secret keys even when the prepared states are uncharacterized, combining theoretical information security with practical security.
ACTA OPTICA SINICA
(2022)
Article
Optics
Yang-Guang Shan, Zhen-Qiang Yin, Hang Liu, Shuang Wang, Wei Chen, De-Yong He, Guang-Can Guo, Zheng-Fu Han
Summary: In this article, a round-robin-differential-quadrature-phase-shift (RRDQPS) protocol is proposed by introducing four-phase modulations into the round-robin-differential-phase-shift (RRDPS) quantum key distribution (QKD) protocol. The security proof for the general n-photon RRDQPS protocol is provided, making RRDQPS protocol with a practical weak coherent source feasible in experiments. Numerical simulation confirms the advantage of RRDQPS protocol over RRDPS protocol in terms of transmission distance, especially with a small number of pulses.