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

arXiv:1708.04074 · New Journal of Physics

Long-distance continuous-variable quantum key distribution using non-Gaussian state-discrimination detection

Qin Liao, Ying Guo, Duan Huang, Peng Huang, Guihua Zeng

Published Jan 18, 2018• 57 citations
arXivHTMLPDF

Abstract

We propose a long-distance continuous-variable quantum key distribution (CVQKD) with a four-state protocol using non-Gaussian state-discrimination detection. A photon subtraction operation, which is deployed at the transmitter, is used for splitting the signal required for generating the non-Gaussian operation to lengthen the maximum transmission distance of the CVQKD. Whereby an improved state-discrimination detector, which can be deemed as an optimized quantum measurement that allows the discrimination of nonorthogonal coherent states beating the standard quantum limit, is applied at the receiver to codetermine the measurement result with the conventional coherent detector. By tactfully exploiting the multiplexing technique, the resulting signals can be simultaneously transmitted through an untrusted quantum channel, and subsequently sent to the state-discrimination detector and coherent detector, respectively. Security analysis shows that the proposed scheme can lengthen the maximum transmission distance up to hundreds of kilometers. Furthermore, by taking the finite-size effect and composable security into account we obtain the tightest bound of the secure distance, which is more practical than that obtained in the asymptotic limit.

DOI
10.1088/1367-2630/aaa8c4

Related papers

Plug-and-play discrete modulation continuous variable quantum key distribution based on non-Gaussian state-discrimination detection

Xiaodong Wu, Duan Huang

Plug-and-play discrete modulation continuous variable quantum key distribution can generate local oscillator light locally without using two independent lasers, and both signal light and local oscillator are generated from the same laser, which can effectively ensure the practical security of the system and have a completely identical frequency characteristic. In addition, this scheme has good compatibility with efficient error correction codes, and can achieve high reconciliation efficiency even at low signal-to-noise ratio. However, there exists large excess noise in the plug-and-play configuration based on the untrusted source model, which seriously limits the maximum transmission distance of the discrete modulation scheme. To solve this problem, we propose a plug-and-play discrete modulation continuous variable quantum key distribution based on non-Gaussian state-discrimination detection. That is to say, a non-Gaussian state-discrimination detector is deployed at the receiver. With adaptive measurement method and Bayesian inference, four non-orthogonal coherent states which are based on four-state discrete modulation can be unconditionally distinguished on condition that the error probability is lower than the standard quantum limit. We analyze the security of the proposed protocol by considering both asymptotic limit and finite-size effect. Simulation results show that the secret key rate and maximum transmission distance are significantly enhanced by using no-Gaussian state-discrimination detection even under the influence of the untrusted source noise compared with the original plug-and-play discrete modulation continuous variable quantum key distribution. These results indicate that the proposed scheme can effectively reduce the negative influence of the untrust source noise on the performance of the plug-and-play discrete modulation continuous variable quantum key distribution protocol. The proposed protocol can not only ensure the practical security of the system, but also achieve more efficient and longer transmission distance quantum key distribution.

Acta Physica Sinica•Dec 27, 2022•4 citations

Continuous variable quantum key distribution based on state-discrimination detector

LIAO Qin, TANG Chong, Junyue Yang +1 more

Aiming at the problem that the traditional coherent detector was limited by the standard quantum limit (SQL) in the continuous variable quantum key distribution (CVQKD) protocol, a CVQKD protocol based on state-discrimination detector (SDD), namely SDD-CVQKD, was proposed. The protocol replaced the traditional coherent detector with SDD, and used multi-round adaptive measurement and MAP criterion to achieve high-precision discrimination of discrete modulated coherent states, which reduced the detection error probability. The security bounds were derived under the security model of reverse reconciliation and collective beam-splitting attack. Numerical simulation results show that the proposed protocol is superior to the traditional CVQKD protocol in terms of channel parameters and secret key rate, and even exceeds the PLOB bound, showing higher security.

•Jan 1, 2026•0 citations

State-discrimination attack on discretely modulated continuous-variable quantum key distribution

Peng Huang, Jian Fang, Guihua Zeng

The continuous-variable quantum key distribution (CVQKD) schemes with discrete modulation are proposed to allow distributions of secret keys over long distance due to the sharing of discrete data. However, the nonorthogonal signal states in these schemes can be discriminated by using quantum receivers with low error rates, which may incur state-discrimination (SD) attacks. We consider the feasibility of Eve's attacks on discrete-modulated CVQKD protocol based on the SD receiver. In particular, an intercept-resend attack is proposed on the four-state protocol based on an SD receiver and a heralded noiseless linear amplifier. The security analysis shows that the secret key rate inferred by Alice and Bob can be larger than its true value, which reveals that the original four-state protocol is not secure under the SD attack. Fortunately, the decoy states can be well applied to remedy this defect, but with the cost of complicated practical implementation.

Physical Review A•Apr 28, 2014•42 citations

Continuous-variable quantum key distribution based on non-Gaussian operations with on-off detection

Xiaoting Chen, Fang Jia, Teng Zhao +3 more

Quantum key distribution (QKD) with continuous variable (CV) is an effective method for achieving the high key rate, but is also limited to a short transmission distance. To overcome this limitation, some solutions have been proposed, including non-Gaussian operations, such as photon addition and photon subtraction using ideal photon source and number-resolving detection. Here we consider the effect of non-Gaussian operation for realistic photon source and ideal on-off photon detection. In the realistic case, it is shown that the performance of CVQKD can not be improved by both photon-subtraction/addition on the right side before the entangled source reaches the channel and photon-subtraction on the left side preceding the entangled source to the sender Alice before performing heterodyne detection, but be enhanced by the photon addition on the left side in a long distance case. These results may provide a useful reference for quantum information with continuous variable.

Optics Express•Sep 12, 2023•4 citations

Non-Gaussian postselection and virtual photon subtraction in continuous-variable quantum key distribution

Zhengyu Li, Yichen Zhang, Xiangyu Wang +3 more

Photon subtraction can enhance the performance of continuous-variable quantum key distribution (CV QKD). However, the enhancement effect will be reduced by the imperfections of practical devices, especially the limited efficiency of a single-photon detector. In this paper, we propose a non-Gaussian postselection method to emulate the photon substraction used in coherent-state CV QKD protocols. The virtual photon subtraction not only can avoid the complexity and imperfections of a practical photon-subtraction operation, which extends the secure transmission distance as the ideal case does, but also can be adjusted flexibly according to the channel parameters to optimize the performance. Furthermore, our preliminary tests on the information reconciliation suggest that in the low signal-to-noise ratio regime, the performance of reconciliating the postselected non-Gaussian data is better than that of the Gaussian data, which implies the feasibility of implementing this method practically.

arXiv:1601.02799•Physical Review A•Jan 7, 2016•71 citations

Practical Non-Gaussian Detection for Enhanced Security in CV-QKD Protocols

Joás Lacerda, Lucas Felipe Bezerra de Melo Oliveira, Alexandre B. Tacla

Continuous-variable quantum key distribution (CV-QKD) has emerged as a leading protocol for provably secure cryptographic key exchange, leveraging quantum properties of optical signals while remaining compatible with existing telecom infrastructure.In these systems, the receiver's detection capability directly impacts the rate at which cryptographic keys can be generated, making it a critical factor for real-time secure communications.Conventional coherent reception schemes (based solely on Gaussian operations) are fundamentally limited in their ability to distinguish quantum states, performing below the ultimate limit allowed by quantum mechanics.Overcoming this limitation requires non-Gaussian detection strategies, which can approach this theoretical bound and unlock higher key generation rates.In this work, we investigate the optimized displacement receiver (ODR) -a non-Gaussian strategy that combines a signal preprocessing step with photon countingas an alternative to conventional homodyne detection for CV-QKD protocols employing binary phase-shift keying (BPSK) modulation.We evaluate its security performance under realistic conditions by modeling practical detector imperfections such as efficiency loss and noise.Our results show that the ODR achieves higher secret key rates than conventional homodyne detection for all detector efficiencies, at all distances, and across the range of detector noise relevant for practical devices, directly translating into enhanced cryptographic performance and extended transmission range.

Anais de XXXV Simpósio Brasileiro de Telecomunicações e Processamento de Sinais•Jan 1, 2026•0 citations
We propose a long-distance continuous-variable quantum key distribution (CVQKD) with a four-state protocol using non-Gaussian state-discrimination detection. A photon subtraction operation, which is deployed at the transmitter, is used for splitting the signal required for generating the non-Gaussian operation to lengthen the maximum transmission distance of the CVQKD. Whereby an improved state-discrimination detector, which can be deemed as an optimized quantum measurement that allows the discrimination of nonorthogonal coherent states beating the standard quantum limit, is applied at the receiver to codetermine the measurement result with the conventional coherent detector. By tactfully exploiting the multiplexing technique, the resulting signals can be simultaneously transmitted through an untrusted quantum channel, and subsequently sent to the state-discrimination detector and coherent detector, respectively. Security analysis shows that the proposed scheme can lengthen the maximum transmission distance up to hundreds of kilometers. Furthermore, by taking the finite-size effect and composable security into account we obtain the tightest bound of the secure distance, which is more practical than that obtained in the asymptotic limit.
Plug-and-play discrete modulation continuous variable quantum key distribution can generate local oscillator light locally without using two independent lasers, and both signal light and local oscillator are generated from the same laser, which can effectively ensure the practical security of the system and have a completely identical frequency characteristic. In addition, this scheme has good compatibility with efficient error correction codes, and can achieve high reconciliation efficiency even at low signal-to-noise ratio. However, there exists large excess noise in the plug-and-play configuration based on the untrusted source model, which seriously limits the maximum transmission distance of the discrete modulation scheme. To solve this problem, we propose a plug-and-play discrete modulation continuous variable quantum key distribution based on non-Gaussian state-discrimination detection. That is to say, a non-Gaussian state-discrimination detector is deployed at the receiver. With adaptive measurement method and Bayesian inference, four non-orthogonal coherent states which are based on four-state discrete modulation can be unconditionally distinguished on condition that the error probability is lower than the standard quantum limit. We analyze the security of the proposed protocol by considering both asymptotic limit and finite-size effect. Simulation results show that the secret key rate and maximum transmission distance are significantly enhanced by using no-Gaussian state-discrimination detection even under the influence of the untrusted source noise compared with the original plug-and-play discrete modulation continuous variable quantum key distribution. These results indicate that the proposed scheme can effectively reduce the negative influence of the untrust source noise on the performance of the plug-and-play discrete modulation continuous variable quantum key distribution protocol. The proposed protocol can not only ensure the practical security of the system, but also achieve more efficient and longer transmission distance quantum key distribution.
Aiming at the problem that the traditional coherent detector was limited by the standard quantum limit (SQL) in the continuous variable quantum key distribution (CVQKD) protocol, a CVQKD protocol based on state-discrimination detector (SDD), namely SDD-CVQKD, was proposed. The protocol replaced the traditional coherent detector with SDD, and used multi-round adaptive measurement and MAP criterion to achieve high-precision discrimination of discrete modulated coherent states, which reduced the detection error probability. The security bounds were derived under the security model of reverse reconciliation and collective beam-splitting attack. Numerical simulation results show that the proposed protocol is superior to the traditional CVQKD protocol in terms of channel parameters and secret key rate, and even exceeds the PLOB bound, showing higher security.
The continuous-variable quantum key distribution (CVQKD) schemes with discrete modulation are proposed to allow distributions of secret keys over long distance due to the sharing of discrete data. However, the nonorthogonal signal states in these schemes can be discriminated by using quantum receivers with low error rates, which may incur state-discrimination (SD) attacks. We consider the feasibility of Eve's attacks on discrete-modulated CVQKD protocol based on the SD receiver. In particular, an intercept-resend attack is proposed on the four-state protocol based on an SD receiver and a heralded noiseless linear amplifier. The security analysis shows that the secret key rate inferred by Alice and Bob can be larger than its true value, which reveals that the original four-state protocol is not secure under the SD attack. Fortunately, the decoy states can be well applied to remedy this defect, but with the cost of complicated practical implementation.
Quantum key distribution (QKD) with continuous variable (CV) is an effective method for achieving the high key rate, but is also limited to a short transmission distance. To overcome this limitation, some solutions have been proposed, including non-Gaussian operations, such as photon addition and photon subtraction using ideal photon source and number-resolving detection. Here we consider the effect of non-Gaussian operation for realistic photon source and ideal on-off photon detection. In the realistic case, it is shown that the performance of CVQKD can not be improved by both photon-subtraction/addition on the right side before the entangled source reaches the channel and photon-subtraction on the left side preceding the entangled source to the sender Alice before performing heterodyne detection, but be enhanced by the photon addition on the left side in a long distance case. These results may provide a useful reference for quantum information with continuous variable.
Photon subtraction can enhance the performance of continuous-variable quantum key distribution (CV QKD). However, the enhancement effect will be reduced by the imperfections of practical devices, especially the limited efficiency of a single-photon detector. In this paper, we propose a non-Gaussian postselection method to emulate the photon substraction used in coherent-state CV QKD protocols. The virtual photon subtraction not only can avoid the complexity and imperfections of a practical photon-subtraction operation, which extends the secure transmission distance as the ideal case does, but also can be adjusted flexibly according to the channel parameters to optimize the performance. Furthermore, our preliminary tests on the information reconciliation suggest that in the low signal-to-noise ratio regime, the performance of reconciliating the postselected non-Gaussian data is better than that of the Gaussian data, which implies the feasibility of implementing this method practically.
Continuous-variable quantum key distribution (CV-QKD) has emerged as a leading protocol for provably secure cryptographic key exchange, leveraging quantum properties of optical signals while remaining compatible with existing telecom infrastructure.In these systems, the receiver's detection capability directly impacts the rate at which cryptographic keys can be generated, making it a critical factor for real-time secure communications.Conventional coherent reception schemes (based solely on Gaussian operations) are fundamentally limited in their ability to distinguish quantum states, performing below the ultimate limit allowed by quantum mechanics.Overcoming this limitation requires non-Gaussian detection strategies, which can approach this theoretical bound and unlock higher key generation rates.In this work, we investigate the optimized displacement receiver (ODR) -a non-Gaussian strategy that combines a signal preprocessing step with photon countingas an alternative to conventional homodyne detection for CV-QKD protocols employing binary phase-shift keying (BPSK) modulation.We evaluate its security performance under realistic conditions by modeling practical detector imperfections such as efficiency loss and noise.Our results show that the ODR achieves higher secret key rates than conventional homodyne detection for all detector efficiencies, at all distances, and across the range of detector noise relevant for practical devices, directly translating into enhanced cryptographic performance and extended transmission range.