Quantum key distribution(QKD),rooted in quantum mechanics,offers information-theoretic security.However,practi-cal systems open security threats due to imperfections,notably bright-light blinding attacks targeting sin...Quantum key distribution(QKD),rooted in quantum mechanics,offers information-theoretic security.However,practi-cal systems open security threats due to imperfections,notably bright-light blinding attacks targeting single-photon detectors.Here,we propose a concise,robust defense strategy for protecting single-photon detectors in QKD systems against blinding attacks.Our strategy uses a dual approach:detecting the bias current of the avalanche photodiode(APD)to defend against con-tinuous-wave blinding attacks,and monitoring the avalanche amplitude to protect against pulsed blinding attacks.By integrat-ing these two branches,the proposed solution effectively identifies and mitigates a wide range of bright light injection attempts,significantly enhancing the resilience of QKD systems against various bright-light blinding attacks.This method forti-fies the safeguards of quantum communications and offers a crucial contribution to the field of quantum information security.展开更多
Quantum key distribution(QKD)is a technology that can resist the threat of quantum computers to existing conventional cryptographic protocols.However,due to the stringent requirements of the quantum key generation env...Quantum key distribution(QKD)is a technology that can resist the threat of quantum computers to existing conventional cryptographic protocols.However,due to the stringent requirements of the quantum key generation environment,the generated quantum keys are considered valuable,and the slow key generation rate conflicts with the high-speed data transmission in traditional optical networks.In this paper,for the QKD network with a trusted relay,which is mainly based on point-to-point quantum keys and has complex changes in network resources,we aim to allocate resources reasonably for data packet distribution.Firstly,we formulate a linear programming constraint model for the key resource allocation(KRA)problem based on the time-slot scheduling.Secondly,we propose a new scheduling scheme based on the graded key security requirements(GKSR)and a new micro-log key storage algorithm for effective storage and management of key resources.Finally,we propose a key resource consumption(KRC)routing optimization algorithm to properly allocate time slots,routes,and key resources.Simulation results show that the proposed scheme significantly improves the key distribution success rate and key resource utilization rate,among others.展开更多
The reference-frame-independent(RFI)quantum key distribution(QKD)is suitable for satellite-based links by removing the active alignment on the reference frames.However,how the beam wandering influences the performance...The reference-frame-independent(RFI)quantum key distribution(QKD)is suitable for satellite-based links by removing the active alignment on the reference frames.However,how the beam wandering influences the performance of RFI-QKD remains a pending issue in satellite-to-ground links.In this paper,based on the mathematical model for characterizing beam wandering,we present the security analysis for satellite-to-ground RFI-QKD and analytically derive formulas for calculating the secret key rate with beam wandering.Our simulation results show that the performance of RFI-QKD is better than the Bennett–Brassard 1984(BB84)QKD with beam wandering in asymptotic case.Furthermore,the degree of influences of beam wandering is specifically presented for satellite-to-ground RFI-QKD when statistical fluctuations are taken into account.Our work can provide theoretical support for the realization of RFI-QKD using satellite-to-ground links and have implications for the construction of large-scale satellite-based quantum networks.展开更多
The data post-processing scheme based on two-way classical communication(TWCC)can improve the tolerable bit error rate and extend the maximal transmission distance when used in a quantum key distribution(QKD)system.In...The data post-processing scheme based on two-way classical communication(TWCC)can improve the tolerable bit error rate and extend the maximal transmission distance when used in a quantum key distribution(QKD)system.In this study,we apply the TWCC method to improve the performance of reference-frame-independent quantum key distribution(RFI-QKD),and analyze the influence of the TWCC method on the performance of decoy-state RFI-QKD in both asymptotic and non-asymptotic cases.Our numerical simulation results show that the TWCC method is able to extend the maximal transmission distance from 175 km to 198 km and improve the tolerable bit error rate from 10.48%to 16.75%.At the same time,the performance of RFI-QKD in terms of the secret key rate and maximum transmission distance are still greatly improved when statistical fluctuations are considered.We conclude that RFI-QKD with the TWCC method is of practical interest.展开更多
Encoding system plays a significant role in quantum key distribution(QKD).However,the security and performance of QKD systems can be compromised by encoding misalignment due to the inevitable defects in realistic devi...Encoding system plays a significant role in quantum key distribution(QKD).However,the security and performance of QKD systems can be compromised by encoding misalignment due to the inevitable defects in realistic devices.To alleviate the influence of misalignments,a method exploiting statistics from mismatched basis is proposed to enable uncharacterized sources to generate secure keys in QKD.In this work,we propose a scheme on four-intensity decoy-state quantum key distribution with uncharacterized heralded single-photon sources.It only requires the source states are prepared in a two-dimensional Hilbert space,and can thus reduce the complexity of practical realizations.Moreover,we carry out corresponding numerical simulations and demonstrate that our present four-intensity decoy-state scheme can achieve a much higher key rate compared than a three-intensity decoy-state method,and meantime it can obtain a longer transmission distance compared than the one using weak coherent sources.展开更多
Quantum key distribution(QKD)in principle can provide unconditional secure communication between distant parts.However,when finite-key length is taken into account,the security can only be ensured within certain secur...Quantum key distribution(QKD)in principle can provide unconditional secure communication between distant parts.However,when finite-key length is taken into account,the security can only be ensured within certain security level.In this paper,we adopt the Chernoff bound analysis method to deal with finite-key-size effects,carrying out corresponding investigations on the relationship between the key generation rate and security parameters for different protocols,including BB84,measurement-device-independent and twin-field QKD protocols.Simulation results show that there exists a fundamental limit between the key rate and the security parameters.Therefore,this study can provide valuable references for practical application of QKD,getting a nice balance between the key generation rate and the security level.展开更多
Quantum key distribution(QKD) generates information-theoretical secure keys between two parties based on the physical laws of quantum mechanics. The phase-matching(PM) QKD protocol allows the key rate to break the qua...Quantum key distribution(QKD) generates information-theoretical secure keys between two parties based on the physical laws of quantum mechanics. The phase-matching(PM) QKD protocol allows the key rate to break the quantum channel secret key capacity limit without quantum repeaters, and the security of the protocol is demonstrated by using equivalent entanglement. In this paper, the wavelength division multiplexing(WDM) technique is applied to the PM-QKD protocol considering the effect of crosstalk noise on the secret key rate. The performance of PM-QKD protocol based on WDM with the influence of adjacent classical channels and Raman scattering is analyzed by numerical simulations to maximize the total secret key rate of the QKD, providing a reference for future implementations of QKD based on WDM techniques.展开更多
Quantum key distribution(QKD)is a sophisticated method for securing information by leveraging the principles of quantum mechanics.Its objective is to establish a confidential key between authorized partners who are co...Quantum key distribution(QKD)is a sophisticated method for securing information by leveraging the principles of quantum mechanics.Its objective is to establish a confidential key between authorized partners who are connected via both a quantum channel and a classical authentication channel.This paper presents a comprehensive overview of QKD protocols,chip-based QKD systems,quantum light sources,quantum detectors,fiber-based QKD networks,space-based QKD systems,as well as the applications and prospects of QKD technology.展开更多
The huge discrepancies between actual devices and theoretical assumptions severely threaten the security of quantum key distribution.Recently,a general new framework called the reference technique has attracted wide a...The huge discrepancies between actual devices and theoretical assumptions severely threaten the security of quantum key distribution.Recently,a general new framework called the reference technique has attracted wide attention in defending against the imperfect sources of quantum key distribution.Here,the state preparation flaws,the side channels of mode dependencies,the Trojan horse attacks,and the pulse classical correlations are studied by using the reference technique on the phase-matching protocol.Our simulation results highlight the importance of the actual secure parameters choice for transmitters,which is necessary to achieve secure communication.Increasing the single actual secure parameter will reduce the secure key rate.However,as long as the parameters are set properly,the secure key rate is still high.Considering the influences of multiple actual secure parameters will significantly reduce the secure key rate.These actual secure parameters must be considered when scientists calibrate transmitters.This work is an important step towards the practical and secure implementation of phase-matching protocol.In the future,it is essential to study the main parameters,find out their maximum and general values,classify the multiple parameters as the same parameter,and give countermeasures.展开更多
Quantum key distribution(QKD)system based on passive silica planar lightwave circuit(PLC)asymmetric Mach–Zehnder interferometers(AMZI)is characterized with thermal stability,low loss and sufficient integration scalab...Quantum key distribution(QKD)system based on passive silica planar lightwave circuit(PLC)asymmetric Mach–Zehnder interferometers(AMZI)is characterized with thermal stability,low loss and sufficient integration scalability.However,waveguide stresses,both intrinsic and temperature-induced stresses,have significant impacts on the stable operation of the system.We have designed silica AMZI chips of 400 ps delay,with bend waveguides length equalized for both long and short arms to balance the stresses thereof.The temperature characteristics of the silica PLC AMZI chip are studied.The interference visibility at the single photon level is kept higher than 95%over a wide temperature range of 12℃.The delay time change is 0.321 ps within a temperature change of 40℃.The spectral shift is 0.0011 nm/0.1℃.Temperature-induced delay time and peak wavelength variations do not affect the interference visibility.The experiment results demonstrate the advantage of being tolerant to chip temperature fluctuations.展开更多
Phase-matching quantum key distribution is a promising scheme for remote quantum key distribution,breaking through the traditional linear key-rate bound.In practical applications,finite data size can cause significant...Phase-matching quantum key distribution is a promising scheme for remote quantum key distribution,breaking through the traditional linear key-rate bound.In practical applications,finite data size can cause significant system performance to deteriorate when data size is below 1010.In this work,an improved statistical fluctuation analysis method is applied for the first time to two decoy-states phase-matching quantum key distribution,offering a new insight and potential solutions for improving the key generation rate and the maximum transmission distance while maintaining security.Moreover,we also compare the influence of the proposed improved statistical fluctuation analysis method on system performance with those of the Gaussian approximation and Chernoff-Hoeffding boundary methods on system performance.The simulation results show that the proposed scheme significantly improves the key generation rate and maximum transmission distance in comparison with the Chernoff-Hoeffding approach,and approach the results obtained when the Gaussian approximation is employed.At the same time,the proposed scheme retains the same security level as the Chernoff-Hoeffding method,and is even more secure than the Gaussian approximation.展开更多
Quantum key distribution provides an unconditional secure key sharing method in theory,but the imperfect factors of practical devices will bring security vulnerabilities.In this paper,we characterize the imperfections...Quantum key distribution provides an unconditional secure key sharing method in theory,but the imperfect factors of practical devices will bring security vulnerabilities.In this paper,we characterize the imperfections of the sender and analyze the possible attack strategies of Eve.Firstly,we present a quantized model for distinguishability of decoy states caused by intensity modulation.Besides,considering that Eve may control the preparation of states through hidden variables,we evaluate the security of preparation in practical quantum key distribution(QKD)scheme based on the weak-randomness model.Finally,we analyze the influence of the distinguishability of decoy state to secure key rate,for Eve may conduct the beam splitting attack and control the channel attenuation of different parts.Through the simulation,it can be seen that the secure key rate is sensitive to the distinguishability of decoy state and weak randomness,especially when Eve can control the channel attenuation.展开更多
Post-processing is indispensable in quantum key distribution （QKD）, which is aimed at sharing secret keys between two distant parties. It mainly consists of key reconciliation and privacy amplification, which is use...Post-processing is indispensable in quantum key distribution （QKD）, which is aimed at sharing secret keys between two distant parties. It mainly consists of key reconciliation and privacy amplification, which is used for sharing the same keys and for distilling unconditional secret keys. In this paper, we focus on speeding up the privacy amplification process by choosing a simple multiplicative universal class of hash functions. By constructing an optimal multiplication algorithm based on four basic multiplication algorithms, we give a fast software implementation of length-adaptive privacy amplification. ＂Length-adaptive＂ indicates that the implementation of privacy amplification automatically adapts to different lengths of input blocks. When the lengths of the input blocks are 1 Mbit and 10 Mbit, the speed of privacy amplification can be as fast as 14.86 Mbps and 10.88 Mbps, respectively. Thus, it is practical for GHz or even higher repetition frequency QKD systems.展开更多
In a quantum key distribution（QKD） system, the error rate needs to be estimated for determining the joint probability distribution between legitimate parties, and for improving the performance of key reconciliation....In a quantum key distribution（QKD） system, the error rate needs to be estimated for determining the joint probability distribution between legitimate parties, and for improving the performance of key reconciliation. We propose an efficient error estimation scheme for QKD, which is called parity comparison method（PCM）. In the proposed method, the parity of a group of sifted keys is practically analysed to estimate the quantum bit error rate instead of using the traditional key sampling. From the simulation results, the proposed method evidently improves the accuracy and decreases revealed information in most realistic application situations.展开更多
Recently the performance of the quantum key distribution （QKD） is substantially improved by the decoy state method and the non-orthogonal encoding protocol, separately. In this paper, a practical non-orthogonal deco...Recently the performance of the quantum key distribution （QKD） is substantially improved by the decoy state method and the non-orthogonal encoding protocol, separately. In this paper, a practical non-orthogonal decoy state protocol with a heralded single photon source （HSPS） for QKD is presented. The protocol is based on 4 states with different intensities. i.e. one signal state and three decoy states. The signal state is for generating keys; the decoy states are for detecting the eavesdropping and estimating the fraction of single-photon and two-photon pulses. We have discussed three cases of this protocol, i.e. the general case, the optimal case and the special case. Moreover, the final key rate over transmission distance is simulated. For the low dark count of the HSPS and the utilization of the two-photon pulses, our protocol has a higher key rate and a longer transmission distance than any other decoy state protocol.展开更多
An efficient two-step quantum key distribution （QKD） protocol with orthogonal product states in the （×）（n ≥3） Hilbert space is presented. In this protocol, the particles in the orthogonal product states fo...An efficient two-step quantum key distribution （QKD） protocol with orthogonal product states in the （×）（n ≥3） Hilbert space is presented. In this protocol, the particles in the orthogonal product states form two particle sequences. The sender, Alice, first sends one sequence to the receiver, Bob. After Bob receives the first particle sequence, Alice and Bob check eavesdropping by measuring a fraction of particles randomly chosen. After ensuring the security of the quantum channel, Alice sends the other particle sequence to Bob. By making an orthogonal measurement on the two particle sequences, Bob can obtain the information of the orthogonal product states sent by Alice. This protocol has many distinct features such as great capacity, high efficiency in that it uses all orthogonal product states in distributing the key except those chosen for checking eavesdroppers.展开更多
A quantum key distribution protocol, based on the quantum dense encoding in entangled states, is presented. In this protocol, we introduce an encoding process to encode two classical bits information into one of the f...A quantum key distribution protocol, based on the quantum dense encoding in entangled states, is presented. In this protocol, we introduce an encoding process to encode two classical bits information into one of the four one-qubit unitary operations implemented by Alice and the Bell states measurement implemented by Bob in stead of direct measuring the previously shared Einstein-Podolsky-Rosen pairs by both of the distant parties, Alice and Bob.Considering the practical application we can get the conclusion that our protocol has some advantages. It not only simplifies the measurement which may induce potential errors, but also improves the effectively transmitted rate of the generated qubits by the raw key. Here we also discuss eavesdropping attacks against the scheme and the channel loss.展开更多
This paper develops a QKD （quantum key distribution）-based queueing model to investigate the data delay on QKD link and network, especially that based on trusted relays. It shows the mean packet delay performance of...This paper develops a QKD （quantum key distribution）-based queueing model to investigate the data delay on QKD link and network, especially that based on trusted relays. It shows the mean packet delay performance of the QKD system. Furthermore, it proposes a key buffering policy which could effectively improve the delay performance in practice. The results will be helpful for quality of service in practical QKD systems.展开更多
A new theoretical quantum key distribution scheme based on entanglement swapping is proposed, where four-qubit symmetric W state functions as quantum channel. It is shown that two legitimate users can secretly share a...A new theoretical quantum key distribution scheme based on entanglement swapping is proposed, where four-qubit symmetric W state functions as quantum channel. It is shown that two legitimate users can secretly share a series of key bits by using Bell-state measurements and classical communication.展开更多
A measuring-basis encrypted quantum key distribution scheme is proposed by using twelve nonorthogohal states in a four-state system and the measuring-basis encryption technique. In this scheme, two bits of classical i...A measuring-basis encrypted quantum key distribution scheme is proposed by using twelve nonorthogohal states in a four-state system and the measuring-basis encryption technique. In this scheme, two bits of classical information can be encoded on one four-state particle and the transmitted particles can be fully used.展开更多
基金This work was supported by the Major Scientific and Technological Special Project of Anhui Province(202103a13010004)the Major Scientific and Technological Special Project of Hefei City(2021DX007)+1 种基金the Key R&D Plan of Shandong Province(2020CXGC010105)the China Postdoctoral Science Foundation(2021M700315).
文摘Quantum key distribution(QKD),rooted in quantum mechanics,offers information-theoretic security.However,practi-cal systems open security threats due to imperfections,notably bright-light blinding attacks targeting single-photon detectors.Here,we propose a concise,robust defense strategy for protecting single-photon detectors in QKD systems against blinding attacks.Our strategy uses a dual approach:detecting the bias current of the avalanche photodiode(APD)to defend against con-tinuous-wave blinding attacks,and monitoring the avalanche amplitude to protect against pulsed blinding attacks.By integrat-ing these two branches,the proposed solution effectively identifies and mitigates a wide range of bright light injection attempts,significantly enhancing the resilience of QKD systems against various bright-light blinding attacks.This method forti-fies the safeguards of quantum communications and offers a crucial contribution to the field of quantum information security.
基金Project supported by the Natural Science Foundation of Jilin Province of China(Grant No.20210101417JC).
文摘Quantum key distribution(QKD)is a technology that can resist the threat of quantum computers to existing conventional cryptographic protocols.However,due to the stringent requirements of the quantum key generation environment,the generated quantum keys are considered valuable,and the slow key generation rate conflicts with the high-speed data transmission in traditional optical networks.In this paper,for the QKD network with a trusted relay,which is mainly based on point-to-point quantum keys and has complex changes in network resources,we aim to allocate resources reasonably for data packet distribution.Firstly,we formulate a linear programming constraint model for the key resource allocation(KRA)problem based on the time-slot scheduling.Secondly,we propose a new scheduling scheme based on the graded key security requirements(GKSR)and a new micro-log key storage algorithm for effective storage and management of key resources.Finally,we propose a key resource consumption(KRC)routing optimization algorithm to properly allocate time slots,routes,and key resources.Simulation results show that the proposed scheme significantly improves the key distribution success rate and key resource utilization rate,among others.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.61505261,62101597,61605248,and 61675235)the National Key Research and Development Program of China (Grant No.2020YFA0309702)+2 种基金the China Postdoctoral Science Foundation (Grant No.2021M691536)the Natural Science Foundation of Henan Province,China (Grant Nos.202300410534 and 202300410532)the Fund of the Anhui Initiative in Quantum Information Technologies。
文摘The reference-frame-independent(RFI)quantum key distribution(QKD)is suitable for satellite-based links by removing the active alignment on the reference frames.However,how the beam wandering influences the performance of RFI-QKD remains a pending issue in satellite-to-ground links.In this paper,based on the mathematical model for characterizing beam wandering,we present the security analysis for satellite-to-ground RFI-QKD and analytically derive formulas for calculating the secret key rate with beam wandering.Our simulation results show that the performance of RFI-QKD is better than the Bennett–Brassard 1984(BB84)QKD with beam wandering in asymptotic case.Furthermore,the degree of influences of beam wandering is specifically presented for satellite-to-ground RFI-QKD when statistical fluctuations are taken into account.Our work can provide theoretical support for the realization of RFI-QKD using satellite-to-ground links and have implications for the construction of large-scale satellite-based quantum networks.
基金supported by the National Natural Science Foundation of China(Grant Nos.61505261,62101597,61605248,and 61675235)the National Key Research and Development Program of China(Grant No.2020YFA0309702)+2 种基金the China Postdoctoral Science Foundation(Grant No.2021M691536)the Natural Science Foundation of Henan Province(Grant Nos.202300410534 and 202300410532)the Anhui Initiative in Quantum Information Technologies.
文摘The data post-processing scheme based on two-way classical communication(TWCC)can improve the tolerable bit error rate and extend the maximal transmission distance when used in a quantum key distribution(QKD)system.In this study,we apply the TWCC method to improve the performance of reference-frame-independent quantum key distribution(RFI-QKD),and analyze the influence of the TWCC method on the performance of decoy-state RFI-QKD in both asymptotic and non-asymptotic cases.Our numerical simulation results show that the TWCC method is able to extend the maximal transmission distance from 175 km to 198 km and improve the tolerable bit error rate from 10.48%to 16.75%.At the same time,the performance of RFI-QKD in terms of the secret key rate and maximum transmission distance are still greatly improved when statistical fluctuations are considered.We conclude that RFI-QKD with the TWCC method is of practical interest.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12074194,12104240,and 62101285)the Industrial Prospect and Key Core Technology Projects of Jiangsu Provincial Key Research and Development Program(Grant No.BE2022071)the Natural Science Foundation of Jiangsu Province,China(Grant Nos.BK20192001 and BK20210582).
文摘Encoding system plays a significant role in quantum key distribution(QKD).However,the security and performance of QKD systems can be compromised by encoding misalignment due to the inevitable defects in realistic devices.To alleviate the influence of misalignments,a method exploiting statistics from mismatched basis is proposed to enable uncharacterized sources to generate secure keys in QKD.In this work,we propose a scheme on four-intensity decoy-state quantum key distribution with uncharacterized heralded single-photon sources.It only requires the source states are prepared in a two-dimensional Hilbert space,and can thus reduce the complexity of practical realizations.Moreover,we carry out corresponding numerical simulations and demonstrate that our present four-intensity decoy-state scheme can achieve a much higher key rate compared than a three-intensity decoy-state method,and meantime it can obtain a longer transmission distance compared than the one using weak coherent sources.
基金the Research on Key Technology and Equipment Development of Autonomous and Controllable Lightweight Endogenous Safety of Power Monitoring System(Grant No.5108-202118056A-0-0-00).
文摘Quantum key distribution(QKD)in principle can provide unconditional secure communication between distant parts.However,when finite-key length is taken into account,the security can only be ensured within certain security level.In this paper,we adopt the Chernoff bound analysis method to deal with finite-key-size effects,carrying out corresponding investigations on the relationship between the key generation rate and security parameters for different protocols,including BB84,measurement-device-independent and twin-field QKD protocols.Simulation results show that there exists a fundamental limit between the key rate and the security parameters.Therefore,this study can provide valuable references for practical application of QKD,getting a nice balance between the key generation rate and the security level.
基金supported by the State Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications) (Grant No. IPOC2021ZT10)the National Natural Science Foundation of China (Grant No. 11904333)+1 种基金the Fundamental Research Funds for the Central Universities (Grant No. 2019XDA02)BUPT Innovation and Entrepreneurship Support Program (Grant No. 2022-YC-T051)。
文摘Quantum key distribution(QKD) generates information-theoretical secure keys between two parties based on the physical laws of quantum mechanics. The phase-matching(PM) QKD protocol allows the key rate to break the quantum channel secret key capacity limit without quantum repeaters, and the security of the protocol is demonstrated by using equivalent entanglement. In this paper, the wavelength division multiplexing(WDM) technique is applied to the PM-QKD protocol considering the effect of crosstalk noise on the secret key rate. The performance of PM-QKD protocol based on WDM with the influence of adjacent classical channels and Raman scattering is analyzed by numerical simulations to maximize the total secret key rate of the QKD, providing a reference for future implementations of QKD based on WDM techniques.
基金Project supported by the Innovation Program for Quantum Science and Technology (Grant No.2021ZD0300701)the National Key Research and Development Program of China (Grant No.2018YFA0306403)the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No.XDB43000000)。
文摘Quantum key distribution(QKD)is a sophisticated method for securing information by leveraging the principles of quantum mechanics.Its objective is to establish a confidential key between authorized partners who are connected via both a quantum channel and a classical authentication channel.This paper presents a comprehensive overview of QKD protocols,chip-based QKD systems,quantum light sources,quantum detectors,fiber-based QKD networks,space-based QKD systems,as well as the applications and prospects of QKD technology.
基金the National Key Research and Development Program of China(Grant Nos.2020YFA0309702 and 2020YFA0309701)the National Natural Science Foundation of China(Grant No.62101597)+2 种基金the China Postdoctoral Science Foundation(Grant No.2021M691536)the Natural Science Foundation of Henan(Grant Nos.202300410534 and 202300410532)the Anhui Initiative in Quantum Information Technologies。
文摘The huge discrepancies between actual devices and theoretical assumptions severely threaten the security of quantum key distribution.Recently,a general new framework called the reference technique has attracted wide attention in defending against the imperfect sources of quantum key distribution.Here,the state preparation flaws,the side channels of mode dependencies,the Trojan horse attacks,and the pulse classical correlations are studied by using the reference technique on the phase-matching protocol.Our simulation results highlight the importance of the actual secure parameters choice for transmitters,which is necessary to achieve secure communication.Increasing the single actual secure parameter will reduce the secure key rate.However,as long as the parameters are set properly,the secure key rate is still high.Considering the influences of multiple actual secure parameters will significantly reduce the secure key rate.These actual secure parameters must be considered when scientists calibrate transmitters.This work is an important step towards the practical and secure implementation of phase-matching protocol.In the future,it is essential to study the main parameters,find out their maximum and general values,classify the multiple parameters as the same parameter,and give countermeasures.
基金Project supported by the National Key R&D Program of China (Grant No.2018YFA0306403)the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No.XDB43000000)+1 种基金Innovation Program for Quantum Science and TechnologyComputer Interconnect Technology Alliance Funding (Grant No.20220103)。
文摘Quantum key distribution(QKD)system based on passive silica planar lightwave circuit(PLC)asymmetric Mach–Zehnder interferometers(AMZI)is characterized with thermal stability,low loss and sufficient integration scalability.However,waveguide stresses,both intrinsic and temperature-induced stresses,have significant impacts on the stable operation of the system.We have designed silica AMZI chips of 400 ps delay,with bend waveguides length equalized for both long and short arms to balance the stresses thereof.The temperature characteristics of the silica PLC AMZI chip are studied.The interference visibility at the single photon level is kept higher than 95%over a wide temperature range of 12℃.The delay time change is 0.321 ps within a temperature change of 40℃.The spectral shift is 0.0011 nm/0.1℃.Temperature-induced delay time and peak wavelength variations do not affect the interference visibility.The experiment results demonstrate the advantage of being tolerant to chip temperature fluctuations.
文摘Phase-matching quantum key distribution is a promising scheme for remote quantum key distribution,breaking through the traditional linear key-rate bound.In practical applications,finite data size can cause significant system performance to deteriorate when data size is below 1010.In this work,an improved statistical fluctuation analysis method is applied for the first time to two decoy-states phase-matching quantum key distribution,offering a new insight and potential solutions for improving the key generation rate and the maximum transmission distance while maintaining security.Moreover,we also compare the influence of the proposed improved statistical fluctuation analysis method on system performance with those of the Gaussian approximation and Chernoff-Hoeffding boundary methods on system performance.The simulation results show that the proposed scheme significantly improves the key generation rate and maximum transmission distance in comparison with the Chernoff-Hoeffding approach,and approach the results obtained when the Gaussian approximation is employed.At the same time,the proposed scheme retains the same security level as the Chernoff-Hoeffding method,and is even more secure than the Gaussian approximation.
基金the National Key Research and Development Program of China(Grant No.2020YFA0309702)NSAF(Grant No.U2130205)+3 种基金the National Natural Science Foundation of China(Grant Nos.62101597,61605248,and 61505261)the China Postdoctoral Science Foundation(Grant No.2021M691536)the Natural Science Foundation of Henan(Grant Nos.202300410534 and 202300410532)the Anhui Initiative in Quantum Information Technologies。
文摘Quantum key distribution provides an unconditional secure key sharing method in theory,but the imperfect factors of practical devices will bring security vulnerabilities.In this paper,we characterize the imperfections of the sender and analyze the possible attack strategies of Eve.Firstly,we present a quantized model for distinguishability of decoy states caused by intensity modulation.Besides,considering that Eve may control the preparation of states through hidden variables,we evaluate the security of preparation in practical quantum key distribution(QKD)scheme based on the weak-randomness model.Finally,we analyze the influence of the distinguishability of decoy state to secure key rate,for Eve may conduct the beam splitting attack and control the channel attenuation of different parts.Through the simulation,it can be seen that the secure key rate is sensitive to the distinguishability of decoy state and weak randomness,especially when Eve can control the channel attenuation.
基金supported by the National Basic Research Program of China(Grant Nos.2011CBA00200 and 2011CB921200)the National Natural Science Foundation of China(Grant Nos.60921091 and 61101137)
文摘Post-processing is indispensable in quantum key distribution （QKD）, which is aimed at sharing secret keys between two distant parties. It mainly consists of key reconciliation and privacy amplification, which is used for sharing the same keys and for distilling unconditional secret keys. In this paper, we focus on speeding up the privacy amplification process by choosing a simple multiplicative universal class of hash functions. By constructing an optimal multiplication algorithm based on four basic multiplication algorithms, we give a fast software implementation of length-adaptive privacy amplification. ＂Length-adaptive＂ indicates that the implementation of privacy amplification automatically adapts to different lengths of input blocks. When the lengths of the input blocks are 1 Mbit and 10 Mbit, the speed of privacy amplification can be as fast as 14.86 Mbps and 10.88 Mbps, respectively. Thus, it is practical for GHz or even higher repetition frequency QKD systems.
基金Project supported by the National Basic Research Program of China(Grant Nos.2011CBA00200 and 2011CB921200)the National Natural Science Foundation of China(Grant Nos.61101137,61201239,and 61205118)
文摘In a quantum key distribution（QKD） system, the error rate needs to be estimated for determining the joint probability distribution between legitimate parties, and for improving the performance of key reconciliation. We propose an efficient error estimation scheme for QKD, which is called parity comparison method（PCM）. In the proposed method, the parity of a group of sifted keys is practically analysed to estimate the quantum bit error rate instead of using the traditional key sampling. From the simulation results, the proposed method evidently improves the accuracy and decreases revealed information in most realistic application situations.
基金Project supported by the National Natural Science Foundation of China (Grant No 60578055)the State Key Development Program for Basic Research of China (Grant No 2007CB307001)
文摘Recently the performance of the quantum key distribution （QKD） is substantially improved by the decoy state method and the non-orthogonal encoding protocol, separately. In this paper, a practical non-orthogonal decoy state protocol with a heralded single photon source （HSPS） for QKD is presented. The protocol is based on 4 states with different intensities. i.e. one signal state and three decoy states. The signal state is for generating keys; the decoy states are for detecting the eavesdropping and estimating the fraction of single-photon and two-photon pulses. We have discussed three cases of this protocol, i.e. the general case, the optimal case and the special case. Moreover, the final key rate over transmission distance is simulated. For the low dark count of the HSPS and the utilization of the two-photon pulses, our protocol has a higher key rate and a longer transmission distance than any other decoy state protocol.
基金Project supported by the National Natural Science Foundation of China （Grant No 60373059）, the Doctoral Programs Foundation of the Ministry of Education of China （Grant No 20040013007）, and the Major Research plan of the National Natural Science Foundation of China （Grant No 90604023）.
文摘An efficient two-step quantum key distribution （QKD） protocol with orthogonal product states in the （×）（n ≥3） Hilbert space is presented. In this protocol, the particles in the orthogonal product states form two particle sequences. The sender, Alice, first sends one sequence to the receiver, Bob. After Bob receives the first particle sequence, Alice and Bob check eavesdropping by measuring a fraction of particles randomly chosen. After ensuring the security of the quantum channel, Alice sends the other particle sequence to Bob. By making an orthogonal measurement on the two particle sequences, Bob can obtain the information of the orthogonal product states sent by Alice. This protocol has many distinct features such as great capacity, high efficiency in that it uses all orthogonal product states in distributing the key except those chosen for checking eavesdroppers.
文摘A quantum key distribution protocol, based on the quantum dense encoding in entangled states, is presented. In this protocol, we introduce an encoding process to encode two classical bits information into one of the four one-qubit unitary operations implemented by Alice and the Bell states measurement implemented by Bob in stead of direct measuring the previously shared Einstein-Podolsky-Rosen pairs by both of the distant parties, Alice and Bob.Considering the practical application we can get the conclusion that our protocol has some advantages. It not only simplifies the measurement which may induce potential errors, but also improves the effectively transmitted rate of the generated qubits by the raw key. Here we also discuss eavesdropping attacks against the scheme and the channel loss.
基金Project supported by National Fundamental Research Program of China (Grant No 2006CB921900)National Natural Science Foundation of China (Grant Nos 60537020 and 60621064)Knowledge Innovation Project of Chinese Academy of Sciences
文摘This paper develops a QKD （quantum key distribution）-based queueing model to investigate the data delay on QKD link and network, especially that based on trusted relays. It shows the mean packet delay performance of the QKD system. Furthermore, it proposes a key buffering policy which could effectively improve the delay performance in practice. The results will be helpful for quality of service in practical QKD systems.
基金The project supported by National Natural Science Foundation of China under Grant No. 60472017
文摘A new theoretical quantum key distribution scheme based on entanglement swapping is proposed, where four-qubit symmetric W state functions as quantum channel. It is shown that two legitimate users can secretly share a series of key bits by using Bell-state measurements and classical communication.
基金The project supported by the National Fundamental Research Program under Grant No. 2006CB0L0106, National Natural Science Foundation of China under Grant Nos. 60433050, 10325521, and 10447106, and the SRFDP Program of Education Ministry of China and Beijing Education Committee under Grant No. XK100270454
文摘A measuring-basis encrypted quantum key distribution scheme is proposed by using twelve nonorthogohal states in a four-state system and the measuring-basis encryption technique. In this scheme, two bits of classical information can be encoded on one four-state particle and the transmitted particles can be fully used.
