Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Dianzi xuebao

Design of Electronics for Phase Coding QKD System

Zheng‐Fu Han

Published Jan 1, 2011• 2 citations
OpenAlex

Abstract

Phase coding is frequently used in current quantum key distribution(QKD) systems.It has posed many technical challenges on the design of the control electronics.After the description to the overall design of our phase coding QKD system,the paper focuses on the special requirements and implementations on the synchronizing mechanism and automatic phase drift scanning and compensation.The electronics designed in this paper combining with the optical devices can be an independent node device of a QKD network.We have successfully used these node devices to build a practical encrypted communication system through the commercial communication optical fiber system of Wuhu Telecom in Anhui Province.Encrypted communication between multiple nodes by quantum cryptography is implemented in this system.The QKD system in the network actualizes BB84 phase coding protocol at 20MHz repetition rate of light pulses.It achieves quantum bit error rate(QBER)2.95% and secure key generation rate 4.91kbps with a 20km transmission distance.

Related papers

High-speed phase-encoded quantum key distribution over a 1.4-km free-space channel

Li Zhang, Fang‐Xiang Wang, Haiyang Fu +10 more

Quantum Key Distribution (QKD) represents a groundbreaking cryptographic technology that enables theoretically unconditionally secure key generation between communication parties. With recent advancements in network integration, QKD systems have been successfully deployed across diverse complex scenarios. For last-mile access network applications, free-space optical channels emerge as an optimal transmission medium. In this work, we implement a free-space QKD system employing a high-repetition-rate phase-encoding BB84 protocol. The experimental setup incorporates a simplified, highly integrable synchronization apparatus and self-compensating phase drift correction mechanism, which enhances both system stability and secure key generation rate. Experimental results demonstrate robust performance over a 1.4-km free-space channel with approximately 13 dB attenuation, achieving a secure key rate (SKR) of 160.19 kbps while maintaining a quantum bit error rate (QBER) of 2.3%. These findings establish the feasibility and efficiency of phase-encoded free-space QKD for last-mile access network applications.

Optica Quantum•Feb 9, 2026•1 citation

Real-time compensation of phase drift for phase-encoded quantum key distribution systems

Lijun Zhang, Yonggang Wang, Zhen−Qiang Yin +7 more

Phase drift is an inherent problem in phase-encoded quantum key distribution (QKD) systems. The current active phase tracking and compensation solutions cannot satisfy the requirements of a system with nonlinearity in phase modulation. This paper presents a four-phase scanning method, which is based on the quantitative analysis of the quantum bit error rate (QBER) from phase drift and the performance requirements of phase compensation. By obtaining the four interference fringes and adjusting the coding matrix of the system, this method automatically calculates the accurate driving voltages for the phase modulator. The implementation and experimental tests show that the proposed method can compensate phase drift caused by environmental changes and the system’s nonlinearity, and is applicable to large-scale QKD networks.

Chinese Science Bulletin•Jul 11, 2011•21 citations

Phase encoded quantum key distribution up to 380 km in standard telecom grade fiber enabled by baseline error optimization

Nishant Kumar Pathak, Sumit Chaudhary, Sangeeta +1 more

Phase encoding in quantum key distribution (QKD) enables long-distance information-theoretic secure communication in optical fibers. We present a novel theoretical model characterizing errors from various sources in practical phase encoding-based QKD systems, namely the laser linewidth, detector dark counts, and channel dispersion. This model provides optimized optical pulse parameters and less distortion in pulses, which eliminates system imperfections and leads to a reduced quantum bit error rate (QBER) for practical QKD scenario. This analysis is applicable to various fiber-based phase and time encoding protocols. In particular, we implement this to a differential phase shift (DPS) QKD scheme operating at a 2.5 GHz clock, which produces a secure key rate of 193 bits/s at a fiber length of 265 km and an unprecedented QBER < 1[Formula: see text] up to 225 km length with standard telecom components. We show that by adjusting the quantum efficiency and dark count rates of detectors, proposed system can establish secure keys up to 380 km distance using standard telecom grade fiber with a QBER of 1.48%. Moreover, the system is compatible with existing optical fiber networks and capable of establishing a secure key exchange between two cities 432 km apart using ultra-low-loss (ULL) specialty fiber.

Scientific Reports•Sep 22, 2023•27 citations

Real-Time Phase Tracking Scheme With Mismatched-Basis Data for Phase-Coding Quantum Key Distribution

Dong Wang, Xiaotian Song, Liangjiang Zhou +1 more

Phase drift is an inevitable problem in the practical implementation of phase-coding quantum key distribution (QKD) systems. Conventional active phase tracking and compensation solutions cannot be implemented during the key transmission process, resulting in reduced efficiency of the system. In this paper, we propose a single-photon level real-time phase tracking scheme using only the estimated quantum bit error rate (QBER) and mismatched-basis data to acquire the phase drift parameter instead of a phase scanning process or reference light pulses, without extra hardware or interrupting the transmission of quantum signals. This scheme is applied into a phase-coding QKD system with active phase disturbance and obtains an average QBER of $1.01\%$ with a standard derivation of $0.37\%$ over 50 h of continuous operation. Experimental results show that this scheme enables QKD systems to operate continuously with long-term stability and keep a low level of QBER even with rapid phase drift, suggesting its suitability for practical applications.

IEEE photonics journal•Apr 13, 2020•9 citations

Experimental demonstration of a local active phase compensation method for a phase encoding quantum key distribution system

Yue Zhang, Junyue Yin, Huiqing Zhao +7 more

An efficient phase stabilization method is required in quantum key distribution (QKD) systems for stability in practical applications. The existing active phase compensation method has limitations in multi-node network applications, especially in network-scale applications based on measurement-device-independent QKD systems. In this study, we propose a local active phase compensation scheme that can realize phase compensation independently for each interferometer node. We performed experimental demonstrations in the BB84 phase encoding system based on a Faraday-Michelson interferometer. The average QBER rates of the system under two different forms of the reference light were found to be 1.9% and 1.6%. This scheme can also be applied to other QKD systems and has potential for application in future quantum communication networks.

Applied Optics•Aug 19, 2022•2 citations

Implementation of Quantum Key Distribution for Secure data transmission in Optical Communication

S. Krithiga, Ajay V, R Manoojitth +1 more

Quantum Key Distribution (QKD) is a potential defense against future quantum attacks that can break traditional encryption algorithms, such as RSA and ECC. The current work is based on the development of the BB84 protocol with the features of utilizing quantum mechanics and eavesdropping detection through signal disturbance. A simulation of the BB84 protocol was built using polarization encoding over a 10 km single-mode optical fiber using OptiSystem software. The system consists of standard telecom equipment, such as a continuous wave laser at a frequency of 193.1 THz, polarization controllers, and single-photon detectors. Both secure and insecure cases were simulated, where an attacker (Eve) had used an intercept-resend attack. The outcome showed significant Bit Error Rate (BER) and Quantum Bit Error Rate (QBER) increases during attacks, thus proving the protocol's vulnerability to interference. In addition, a special intrusion detection system based on BER was used to identify such anomalies in real-time. The simulation illustrates the feasibility of using QKD in today's optical networks to secure communications.

International Conference on Emerging Research in Electronics, Computer Science and Technology (ICERECT)•Sep 12, 2025•0 citations
Phase coding is frequently used in current quantum key distribution(QKD) systems.It has posed many technical challenges on the design of the control electronics.After the description to the overall design of our phase coding QKD system,the paper focuses on the special requirements and implementations on the synchronizing mechanism and automatic phase drift scanning and compensation.The electronics designed in this paper combining with the optical devices can be an independent node device of a QKD network.We have successfully used these node devices to build a practical encrypted communication system through the commercial communication optical fiber system of Wuhu Telecom in Anhui Province.Encrypted communication between multiple nodes by quantum cryptography is implemented in this system.The QKD system in the network actualizes BB84 phase coding protocol at 20MHz repetition rate of light pulses.It achieves quantum bit error rate(QBER)2.95% and secure key generation rate 4.91kbps with a 20km transmission distance.
Quantum Key Distribution (QKD) represents a groundbreaking cryptographic technology that enables theoretically unconditionally secure key generation between communication parties. With recent advancements in network integration, QKD systems have been successfully deployed across diverse complex scenarios. For last-mile access network applications, free-space optical channels emerge as an optimal transmission medium. In this work, we implement a free-space QKD system employing a high-repetition-rate phase-encoding BB84 protocol. The experimental setup incorporates a simplified, highly integrable synchronization apparatus and self-compensating phase drift correction mechanism, which enhances both system stability and secure key generation rate. Experimental results demonstrate robust performance over a 1.4-km free-space channel with approximately 13 dB attenuation, achieving a secure key rate (SKR) of 160.19 kbps while maintaining a quantum bit error rate (QBER) of 2.3%. These findings establish the feasibility and efficiency of phase-encoded free-space QKD for last-mile access network applications.
Phase drift is an inherent problem in phase-encoded quantum key distribution (QKD) systems. The current active phase tracking and compensation solutions cannot satisfy the requirements of a system with nonlinearity in phase modulation. This paper presents a four-phase scanning method, which is based on the quantitative analysis of the quantum bit error rate (QBER) from phase drift and the performance requirements of phase compensation. By obtaining the four interference fringes and adjusting the coding matrix of the system, this method automatically calculates the accurate driving voltages for the phase modulator. The implementation and experimental tests show that the proposed method can compensate phase drift caused by environmental changes and the system’s nonlinearity, and is applicable to large-scale QKD networks.
Phase encoding in quantum key distribution (QKD) enables long-distance information-theoretic secure communication in optical fibers. We present a novel theoretical model characterizing errors from various sources in practical phase encoding-based QKD systems, namely the laser linewidth, detector dark counts, and channel dispersion. This model provides optimized optical pulse parameters and less distortion in pulses, which eliminates system imperfections and leads to a reduced quantum bit error rate (QBER) for practical QKD scenario. This analysis is applicable to various fiber-based phase and time encoding protocols. In particular, we implement this to a differential phase shift (DPS) QKD scheme operating at a 2.5 GHz clock, which produces a secure key rate of 193 bits/s at a fiber length of 265 km and an unprecedented QBER < 1[Formula: see text] up to 225 km length with standard telecom components. We show that by adjusting the quantum efficiency and dark count rates of detectors, proposed system can establish secure keys up to 380 km distance using standard telecom grade fiber with a QBER of 1.48%. Moreover, the system is compatible with existing optical fiber networks and capable of establishing a secure key exchange between two cities 432 km apart using ultra-low-loss (ULL) specialty fiber.
Phase drift is an inevitable problem in the practical implementation of phase-coding quantum key distribution (QKD) systems. Conventional active phase tracking and compensation solutions cannot be implemented during the key transmission process, resulting in reduced efficiency of the system. In this paper, we propose a single-photon level real-time phase tracking scheme using only the estimated quantum bit error rate (QBER) and mismatched-basis data to acquire the phase drift parameter instead of a phase scanning process or reference light pulses, without extra hardware or interrupting the transmission of quantum signals. This scheme is applied into a phase-coding QKD system with active phase disturbance and obtains an average QBER of 1.01%1.01\%1.01% with a standard derivation of 0.37%0.37\%0.37% over 50 h of continuous operation. Experimental results show that this scheme enables QKD systems to operate continuously with long-term stability and keep a low level of QBER even with rapid phase drift, suggesting its suitability for practical applications.
An efficient phase stabilization method is required in quantum key distribution (QKD) systems for stability in practical applications. The existing active phase compensation method has limitations in multi-node network applications, especially in network-scale applications based on measurement-device-independent QKD systems. In this study, we propose a local active phase compensation scheme that can realize phase compensation independently for each interferometer node. We performed experimental demonstrations in the BB84 phase encoding system based on a Faraday-Michelson interferometer. The average QBER rates of the system under two different forms of the reference light were found to be 1.9% and 1.6%. This scheme can also be applied to other QKD systems and has potential for application in future quantum communication networks.
Quantum Key Distribution (QKD) is a potential defense against future quantum attacks that can break traditional encryption algorithms, such as RSA and ECC. The current work is based on the development of the BB84 protocol with the features of utilizing quantum mechanics and eavesdropping detection through signal disturbance. A simulation of the BB84 protocol was built using polarization encoding over a 10 km single-mode optical fiber using OptiSystem software. The system consists of standard telecom equipment, such as a continuous wave laser at a frequency of 193.1 THz, polarization controllers, and single-photon detectors. Both secure and insecure cases were simulated, where an attacker (Eve) had used an intercept-resend attack. The outcome showed significant Bit Error Rate (BER) and Quantum Bit Error Rate (QBER) increases during attacks, thus proving the protocol's vulnerability to interference. In addition, a special intrusion detection system based on BER was used to identify such anomalies in real-time. The simulation illustrates the feasibility of using QKD in today's optical networks to secure communications.