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

Physica Scripta

Thermal state continuous-variable quantum key distribution via fast fading channel

Yue Xia Tian, Jian Zhou, Runbo Zhao, Ronghua Shi, Jinjing Shi, Yanyan Feng

Published Jun 23, 2025• 0 citations
Publisher

Abstract

Abstract This study examines the implementation of continuous-variable quantum key distribution (CV-QKD) using thermal states via fast fading channel. In such channel, communication occurs in free space under adverse conditions such as atmospheric turbulence, causing the channel transmittance to vary according to a specific mathematical probability. In worst-case scenarios, an eavesdropper could fully control the channel, leaving communicators to make pessimistic assumptions about channel conditions. The security of this system is analyzed and evaluated using homodyne and heterodyne detection methods under reverse reconciliation. The results indicate that even with full eavesdropper control, employing noise sources in CV-QKD ensures high key rates and protocol security. Furthermore, it has been demonstrated that the introduction of preparation noise in heterodyne detection is more effective than homodyne detection under fast fading channel conditions.

DOI
10.1088/1402-4896/ade6db

Related papers

Continuous-variable quantum key distribution in uniform fast-fading channels

Panagiotis Papanastasiou, Christian Weedbrook, Stefano Pirandola

We investigate the performance of several continuous-variable quantum key distribution protocols in the presence of uniform fading channels. These are lossy channels whose transmissivity changes according to a uniform probability distribution. We assume the worst-case scenario where an eavesdropper induces a fast-fading process, where she chooses the instantaneous transmissivity while the remote parties may only detect the mean statistical effect. We analyze coherent-state protocols in various configurations, including the one-way switching protocol in reverse reconciliation, the measurement-device-independent protocol in the symmetric configuration, and its extension to a three-party network. We show that, regardless of the advantage given to the eavesdropper (control of the fading), these protocols can still achieve high rates under realistic attacks, within reasonable values for the variance of the probability distribution associated with the fading process.

arXiv:1710.03525•Physical Review A•Mar 12, 2018•59 citations

Free space continuous-variable quantum key distribution with practical links

Ming Li, Tianyi Wang, Jiawei Han +4 more

The transmittance fluctuation resulting from free space optics will impart the continuous-variable quantum key distribution (CV-QKD). In this paper, we study the CV-QKD over free space by taking practical transmittance fluctuation into account. The transmittance is modeled following the Gaussian distribution, which reflects the most realistic fluctuation since all sources of perturbation are required to be incorporated together in practice. The comprehensive comparison between the practical model and existing models in secret key rate is drawn. The numerical results reveal that the existing model of uniform distribution underestimates the impact of air link for both slow and fast fading scenarios, and the practical secret key rate will suffer severer degradation. Further, as the variance of the Gaussian model decreases, the secret key rate degrades as well. Also, a comparison between heterodyne and homodyne detection schemes is made, and we found that the heterodyne detection outperforms the homodyne detection in the secret key rate for both the slow and fast fading air quantum channels.

Journal of the Optical Society of America B•Oct 8, 2020•12 citations

Discrete modulation continuous variable quantum key distribution under fast fading channel

Jinyi Li, Jian Zhou, Yanyan Feng +2 more

Abstract After decades of development, continuous variable quantum key distribution technology still cannot meet people’s needs for secure communication over long distances. Free-space quantum communication provides a new way for secure communication over long distances. However, because the communication connected in free space is inevitably affected by atmospheric turbulence, the transmission rate of the channel changes rapidly according to the probability distribution, making it difficult for the communication personnel to determine the transmission rate of the channel. At the same time, discrete modulated continuously variable quantum key Distribution protocol (DM-CVQKD) has certain advantages over Gauss modulated continuously variable quantum key Distribution protocol (GM-CVQKD) in the communication distance. Therefore, this paper analyzes the key rate of DM-CVQKD in this case (that is, in the fast attenuation channel), proves that it can resist the collective attack, and observes the relationship between the parameters and the key rate in the fast attenuation channel by numerical simulation and control variables. Finally, through the analysis of numerical simulation results, it is found that DM-CVQKD can still maintain a high key rate under certain conditions, which proves that long-distance free space quantum communication is feasible under certain conditions. At the same time, it was found that the performance of DM-CVQKD was affected by the extreme case where Eve completely controlled the instantaneous transmittance.

Physica Scripta•Oct 11, 2024•0 citations

Continuous-variable quantum key distribution using thermal states

Christian Weedbrook, Stefano Pirandola, Timothy C. Ralph

We consider the security of continuous-variable quantum key distribution using thermal (or noisy) Gaussian resource states. Specifically, we analyze this against collective Gaussian attacks using direct and reverse reconciliation where both protocols use either homodyne or heterodyne detection. We show that in the case of direct reconciliation with heterodyne detection, an improved robustness to channel noise is achieved when large amounts of preparation noise is added, as compared to the case when no preparation noise is added. We also consider the theoretical limit of infinite preparation noise and show a secure key can still be achieved in this limit provided the channel noise is less than the preparation noise. Finally, we consider the security of quantum key distribution at various electromagnetic wavelengths and derive an upper bound related to an entanglement-breaking eavesdropping attack and discuss the feasibility of microwave quantum key distribution.

arXiv:1110.4617•Physical Review A•Aug 17, 2012•140 citations

Unidimensional Continuous Variable Quantum Key Distribution under Fast Fading Channel

Runbo Zhao, Jian Zhou, Ronghua Shi +1 more

Abstract In this paper, the performance of a unidimensional continuous variable quantum key distribution protocol is analyzed using Gaussian modulated coherent state under fast fading channel. In the fast fading channel, both parties are connected in free space, resulting in a harsh propagation environment and pollution caused by atmospheric turbulence. This pollution makes it difficult for the communicators to determine the channel transmittance, which can only be estimated based on a probability distribution. To address this, only one modulator is used to code, which demonstrates performance equivalent to that of the symmetric modulated Gaussian coherent state protocol. The security of the protocol in the face of collective attacks is analyzed and it is proved that it can accept a certain amount of excessive channel noise while simplifying operations. Simultaneously, the impact of finite‐key length effects on the protocol is analyzed. It is also demonstrated that this protocol can reduce costs within an acceptable range of performance losses, making it more practical.

Annalen der Physik•Dec 14, 2023•8 citations

Continuous-variable measurement-device-independent multipartite quantum communication via a fast-fading channel

Runbo Zhao, Jian Zhou, Ronghua Shi +2 more

This study investigates the implementation of measurement-device-independent multiparty quantum communication using continuous-variable Greenberger-Horne-Zeilinger (CV GHZ) states under the fast fading channel. The communication parties are connected through free space, and factors such as atmospheric turbulence cause beam drift, resulting in variations in channel transmittance according to specific probability distributions. We assume a worst-case scenario in which an eavesdropper has complete control over the channel, forcing the communicators to estimate the channel based on this probability distribution. The protocol employs CV GHZ states to achieve secure communication through quantum cryptographic conference and quantum secret sharing. For the aspect of security, independent entangling cloner attack and coherent attack are analyzed. Simulation results demonstrate that the protocol can withstand advantageous attacks from eavesdroppers.

Physical Review A•Jan 13, 2025•10 citations
Abstract This study examines the implementation of continuous-variable quantum key distribution (CV-QKD) using thermal states via fast fading channel. In such channel, communication occurs in free space under adverse conditions such as atmospheric turbulence, causing the channel transmittance to vary according to a specific mathematical probability. In worst-case scenarios, an eavesdropper could fully control the channel, leaving communicators to make pessimistic assumptions about channel conditions. The security of this system is analyzed and evaluated using homodyne and heterodyne detection methods under reverse reconciliation. The results indicate that even with full eavesdropper control, employing noise sources in CV-QKD ensures high key rates and protocol security. Furthermore, it has been demonstrated that the introduction of preparation noise in heterodyne detection is more effective than homodyne detection under fast fading channel conditions.
We investigate the performance of several continuous-variable quantum key distribution protocols in the presence of uniform fading channels. These are lossy channels whose transmissivity changes according to a uniform probability distribution. We assume the worst-case scenario where an eavesdropper induces a fast-fading process, where she chooses the instantaneous transmissivity while the remote parties may only detect the mean statistical effect. We analyze coherent-state protocols in various configurations, including the one-way switching protocol in reverse reconciliation, the measurement-device-independent protocol in the symmetric configuration, and its extension to a three-party network. We show that, regardless of the advantage given to the eavesdropper (control of the fading), these protocols can still achieve high rates under realistic attacks, within reasonable values for the variance of the probability distribution associated with the fading process.
The transmittance fluctuation resulting from free space optics will impart the continuous-variable quantum key distribution (CV-QKD). In this paper, we study the CV-QKD over free space by taking practical transmittance fluctuation into account. The transmittance is modeled following the Gaussian distribution, which reflects the most realistic fluctuation since all sources of perturbation are required to be incorporated together in practice. The comprehensive comparison between the practical model and existing models in secret key rate is drawn. The numerical results reveal that the existing model of uniform distribution underestimates the impact of air link for both slow and fast fading scenarios, and the practical secret key rate will suffer severer degradation. Further, as the variance of the Gaussian model decreases, the secret key rate degrades as well. Also, a comparison between heterodyne and homodyne detection schemes is made, and we found that the heterodyne detection outperforms the homodyne detection in the secret key rate for both the slow and fast fading air quantum channels.
Abstract After decades of development, continuous variable quantum key distribution technology still cannot meet people’s needs for secure communication over long distances. Free-space quantum communication provides a new way for secure communication over long distances. However, because the communication connected in free space is inevitably affected by atmospheric turbulence, the transmission rate of the channel changes rapidly according to the probability distribution, making it difficult for the communication personnel to determine the transmission rate of the channel. At the same time, discrete modulated continuously variable quantum key Distribution protocol (DM-CVQKD) has certain advantages over Gauss modulated continuously variable quantum key Distribution protocol (GM-CVQKD) in the communication distance. Therefore, this paper analyzes the key rate of DM-CVQKD in this case (that is, in the fast attenuation channel), proves that it can resist the collective attack, and observes the relationship between the parameters and the key rate in the fast attenuation channel by numerical simulation and control variables. Finally, through the analysis of numerical simulation results, it is found that DM-CVQKD can still maintain a high key rate under certain conditions, which proves that long-distance free space quantum communication is feasible under certain conditions. At the same time, it was found that the performance of DM-CVQKD was affected by the extreme case where Eve completely controlled the instantaneous transmittance.
We consider the security of continuous-variable quantum key distribution using thermal (or noisy) Gaussian resource states. Specifically, we analyze this against collective Gaussian attacks using direct and reverse reconciliation where both protocols use either homodyne or heterodyne detection. We show that in the case of direct reconciliation with heterodyne detection, an improved robustness to channel noise is achieved when large amounts of preparation noise is added, as compared to the case when no preparation noise is added. We also consider the theoretical limit of infinite preparation noise and show a secure key can still be achieved in this limit provided the channel noise is less than the preparation noise. Finally, we consider the security of quantum key distribution at various electromagnetic wavelengths and derive an upper bound related to an entanglement-breaking eavesdropping attack and discuss the feasibility of microwave quantum key distribution.
Abstract In this paper, the performance of a unidimensional continuous variable quantum key distribution protocol is analyzed using Gaussian modulated coherent state under fast fading channel. In the fast fading channel, both parties are connected in free space, resulting in a harsh propagation environment and pollution caused by atmospheric turbulence. This pollution makes it difficult for the communicators to determine the channel transmittance, which can only be estimated based on a probability distribution. To address this, only one modulator is used to code, which demonstrates performance equivalent to that of the symmetric modulated Gaussian coherent state protocol. The security of the protocol in the face of collective attacks is analyzed and it is proved that it can accept a certain amount of excessive channel noise while simplifying operations. Simultaneously, the impact of finite‐key length effects on the protocol is analyzed. It is also demonstrated that this protocol can reduce costs within an acceptable range of performance losses, making it more practical.
This study investigates the implementation of measurement-device-independent multiparty quantum communication using continuous-variable Greenberger-Horne-Zeilinger (CV GHZ) states under the fast fading channel. The communication parties are connected through free space, and factors such as atmospheric turbulence cause beam drift, resulting in variations in channel transmittance according to specific probability distributions. We assume a worst-case scenario in which an eavesdropper has complete control over the channel, forcing the communicators to estimate the channel based on this probability distribution. The protocol employs CV GHZ states to achieve secure communication through quantum cryptographic conference and quantum secret sharing. For the aspect of security, independent entangling cloner attack and coherent attack are analyzed. Simulation results demonstrate that the protocol can withstand advantageous attacks from eavesdroppers.