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Multi-carrier continuous-variable quantum key distribution (CV-QKD) is considered to be a promising way to boost the secret key rate (SKR) over the existing single-carrier CV-QKD scheme. However, the extra excess noise induced in the…

Quantum Physics · Physics 2023-03-22 Heng Wang , Yan Pan , Yun Shao , Yaodi Pi , Ting Ye , Yang Li , Tao Zhang , Jinlu Liu , Jie Yang , Li Ma , Wei Huang , Bingjie Xu

Continuous-variable quantum key distribution (CV-QKD) enables two remote parties to establish information-theoretically secure keys and offers high practical feasibility due to its compatibility with mature coherent optical communication…

Quantum Physics · Physics 2025-12-18 Yanhao Sun , Jiayu Ma , Xiangyu Wang , Song Yu , Ziyang Chen , Hong Guo

Coherent measurement of quantum signals used for continuous-variable (CV) quantum key distribution (QKD) across satellite-to-ground channels requires compensation of phase wavefront distortions caused by atmospheric turbulence. One…

Quantum Physics · Physics 2025-08-13 Nathan K. Long , Robert Malaney , Kenneth J. Grant

In this paper we demonstrate an active polarization drift compensation scheme for optical fibres employed in a quantum key distribution experiment with polarization encoded qubits. The quantum signals are wavelength multiplexed in one fibre…

The value of residual phase noise, after phase compensation, is one of the key limitations of performance improvement for continuous-variable quantum key distribution using a local local oscillator (LLO CV-QKD) system, since it is the major…

Quantum Physics · Physics 2023-03-22 Yun Shao , Heng Wang , Yaodi Pi , Wei Huang , Yang Li , Jinlu Liu , Jie Yang , Yichen Zhang , Bingjie Xu

The advent of quantum computers has significantly challenged the security of traditional cryptographic systems, prompting a surge in research on quantum key distribution (QKD). Among various QKD approaches, continuous-variable QKD (CVQKD)…

Quantum Physics · Physics 2025-03-26 Xiaojuan Liao , Yuehan Xu , Qijun Zhang , Peng Huang , Tao Wang , Kaizhi Wang , Guihua Zeng

In practical implementation of quantum key distributions (QKD), it requires efficient, real-time feedback control to maintain system stability when facing disturbance from either external environment or imperfect internal components.…

Quantum Physics · Physics 2019-08-07 Jing-Yang Liu , Hua-Jian Ding , Chun-Mei Zhang , Shi-Peng Xie , Qin Wang

We use single homodyne detector to accomplish Continuous-Variable quantum key distribution(CV QKD) in a laboratory and urban environment free-space channel. This is based on Gaussian modulation with coherent-states in the polarization…

Quantum Physics · Physics 2019-07-24 Shi-Yang Shen , Ming-Wei Dai , Xue-Tao Zheng , Qi-Yao Sun , Bing Zhu , Guang-Can Guo , Zheng-Fu Han

In dynamically varying optical wireless communication (OWC) links, conventional quadrature amplitude modulation (QAM) in optical orthogonal frequency-division multiplexing (OFDM) requires frequent channel estimation and equalization,…

Optics · Physics 2026-03-19 Tian Cao , Ping Wang , Tianfeng Wu , Kaile Wang , Jian Song

Measurement-Device-Independent Quantum Key Distribution (MDI-QKD) provides unconditional security against detector vulnerabilities, but its practical deployment is severely hindered by asymmetric channel turbulence. Fluctuations in optical…

Polarizations of single-photon pulses have been controlled with long-term stability of more than 10 hours by using an active feedback technique for auto-compensation of unpredictable polarization scrambling in long-distance fiber.…

Quantum Physics · Physics 2007-05-23 Guang Wu , Jie Chen , Yao Li , Heping Zeng

We consider a continuous-variable (CV) quantum key distribution (QKD) protocol over free-space channels, which is simpler and more robust than typical CV QKD protocols. It uses a bright laser, squeezed and modulated in the amplitude…

Quantum Physics · Physics 2022-03-14 Nedasadat Hosseinidehaj , Matthew S. Winnel , Timothy C. Ralph

This paper introduces two new algorithms to accurately estimate the process noise covariance of a discrete-time Kalman filter online for robust orbit determination in the presence of dynamics model uncertainties. Common orbit determination…

Signal Processing · Electrical Eng. & Systems 2021-05-17 Nathan Stacey , Simone D'Amico

Quantum key distribution (QKD) has emerged as a promising solution to protect current cryptographic systems against the threat of quantum computers. As QKD transitions from laboratories to real-world applications, its implementation under…

Quantum Physics · Physics 2026-05-22 Hashir Kuniyil , Saif Al-Kuwari , Asad Ali , Artur Czerwinski , Syed M. Arslan

The secret key rate of a continuous-variable quantum key distribution (CV-QKD) system is limited by excess noise. A key issue typical to all modern CV-QKD systems implemented with a reference or pilot signal and an independent local…

Quantum Physics · Physics 2021-05-13 Hou-Man Chin , Nitin Jain , Darko Zibar , Ulrik L. Andersen , Tobias Gehring

State-of-the-art free-space continuous-variable quantum key distribution (CV-QKD) protocols use phase reference pulses to modulate the wavefront of a real local oscillator at the receiver, thereby compensating for wavefront distortions…

Discrete-variable (DV) quantum key distribution (QKD) based on single-photon detectors and sources have been successfully deployed for long-range secure key distribution. On the other hand, continuous-variable (CV) quantum key distribution…

Quantum Physics · Physics 2024-06-24 Sebastian P. Kish , Patrick J. Gleeson , Angus Walsh , Ping Koy Lam , Syed M. Assad

Information reconciliation protocol has a significant effect on the secret key rate and maximal transmission distance of continuous-variable quantum key distribution (CV-QKD) systems. We propose an efficient rate-adaptive reconciliation…

Quantum Physics · Physics 2018-04-12 Xiangyu Wang , Yi-Chen Zhang , Zhengyu Li , Bingjie Xu , Song Yu , Hong Guo

We study the robustness of quantum key distribution protocols using discrete or continuous variables to the channel noise. We introduce the model of such noise based on coupling of the signal to a thermal reservoir, typical for…

Quantum Physics · Physics 2017-06-12 Mikołaj Lasota , Radim Filip , Vladyslav C. Usenko

Continuous-variable (CV) quantum key distribution (QKD) allows for quantum secure communication with the benefit of being close to existing classical coherent communication. In recent years, CV QKD protocols using a discrete number of…