Quantum key distribution(QKD)optical networks can provide more secure communications.However,with the increase of the QKD path requests and key updates,network blocking problems will become severe.The blocking problem...Quantum key distribution(QKD)optical networks can provide more secure communications.However,with the increase of the QKD path requests and key updates,network blocking problems will become severe.The blocking problems in the network can become more severe because each fiber link has limited resources(such as wavelengths and time slots).In addition,QKD optical networks are also affected by external disturbances such as data interception and eavesdropping,resulting in inefficient network communication.In this paper,we exploit the idea of protection path to enhance the anti-interference ability of QKD optical network.By introducing the concept of security metric,we propose a routing wavelength and time slot allocation algorithm(RWTA)based on protection path,which can lessen the blocking problem of QKD optical network.According to simulation analysis,the security-metric-based RWTA algorithm(SM-RWTA)proposed in this paper can substantially improve the success rate of security key(SK)update and significantly reduce the blocking rate of the network.It can also improve the utilization rate of resources such as wavelengths and time slots.Compared with the non-security-metric-based RWTA algorithm(NSM-RWTA),our algorithm is robust and can enhance the anti-interference ability and security of QKD optical networks.展开更多
A mode-pairing quantum key distribution based on heralded pair-coherent source with passive decoy-states is proposed,named HPCS-PDS-MP-QKD protocol,where the light sources at Alice and Bob sides are changed to heralde...A mode-pairing quantum key distribution based on heralded pair-coherent source with passive decoy-states is proposed,named HPCS-PDS-MP-QKD protocol,where the light sources at Alice and Bob sides are changed to heralded pair-coherent sources,and devices designed to implement passive decoy states are included at the transmitter sides to generate the decoy state pulses in the decoy-state window passively.With the defined efficient events and the designed pairing strategy,the key bits and bases can be obtained by data post-processing.Numerical simulation results verify the feasibility of the proposed protocol.The results show that the proposed protocol can exceed PLOB when the pairing interval setting is greater than 10^(3),and the transmission distance exceeds 200 km.When the key transmission distance reaches 300 km and the maximum pairing interval is equivalent to 1,its performance is improved by nearly 1.8 times compared to the original MP-QKD protocol with a weak coherent source(WCS-MP-QKD),and by 6.8 times higher than that of WCS-MPQKD with passive decoy states(WCS-PDS-MP-QKD).Meanwhile,the key transmission distance can reach 480 km,and surpasses the WCS-PDS-MP-QKD protocol by nearly 40 km.When the total pulse length is greater than 10^(11),the key generation rate is almost equal to that of infinite pulses.It is a promising QKD protocol that breaks the PLOB bound without requiring phase tracking and locking,has a longer transmission distance and a higher key generation rate,and eliminates the potential of side channel attack.展开更多
Quantum key distribution(QKD)is a method for secure communication that utilizes quantum mechanics principles to distribute cryptographic keys between parties.Integrated photonics offer benefits such as compactness,sca...Quantum key distribution(QKD)is a method for secure communication that utilizes quantum mechanics principles to distribute cryptographic keys between parties.Integrated photonics offer benefits such as compactness,scalability,energy efficiency and the potential for extensive integration.We have achieved BB84 phase encoding and decoding,time-bin phase QKD,and the coherent one-way(COW)protocol on a planar lightwave circuit(PLC)platform.At the optimal temperature,our chip successfully prepared quantum states,performed decoding and calculated the secure key rate of the time-bin phasedecoding QKD to be 80.46 kbps over a 20 km transmission with a quantum bit error rate(QBER)of 4.23%.The secure key rate of the COW protocol was 18.18 kbps,with a phase error rate of 3.627%and a time error rate of 0.377%.The uniqueness of this technology lies in its combination of high integration and protocol flexibility,providing an innovative solution for the development of future quantum communication networks.展开更多
In the process of quantum key distribution(QKD), the communicating parties need to randomly determine quantum states and measurement bases. To ensure the security of key distribution, we aim to use true random sequenc...In the process of quantum key distribution(QKD), the communicating parties need to randomly determine quantum states and measurement bases. To ensure the security of key distribution, we aim to use true random sequences generated by true random number generators as the source of randomness. In practical systems, due to the difficulty of obtaining true random numbers, pseudo-random number generators are used instead. Although the random numbers generated by pseudorandom number generators are statistically random, meeting the requirements of uniform distribution and independence,they rely on an initial seed to generate corresponding pseudo-random sequences. Attackers may predict future elements from the initial elements of the random sequence, posing a security risk to quantum key distribution. This paper analyzes the problems existing in current pseudo-random number generators and proposes corresponding attack methods and applicable scenarios based on the vulnerabilities in the pseudo-random sequence generation process. Under certain conditions, it is possible to obtain the keys of the communicating parties with very low error rates, thus effectively attacking the quantum key system. This paper presents new requirements for the use of random numbers in quantum key systems, which can effectively guide the security evaluation of quantum key distribution protocols.展开更多
The robustness of reference-frame-independent measurement-device-independent quantum key distribution(RFIMDI-QKD)against detection system vulnerabilities and its tolerance to reference frame drifts make it an ideal ch...The robustness of reference-frame-independent measurement-device-independent quantum key distribution(RFIMDI-QKD)against detection system vulnerabilities and its tolerance to reference frame drifts make it an ideal choice for hybrid channels.However,the impact of atmospheric turbulence on transmittance fluctuations remains a significant challenge for enhancing the performance of RFI-MDI-QKD.In this paper,we apply prefixed-threshold real-time selection and advantage distillation techniques to RFI-MDI-QKD in a hybrid channels scenario.Then,we analytically derive formulas for secret key rate in hybrid channels.Simulation results show that our modified scheme has apparent advances in both maximum tolerant loss and secure key rate compared to the fiber-only channel.Specifically,the result demonstrates that the maximum transmission distance can be improved by 15 km and 28 km when N=10^(12)and 10^(11).Our work not only provides a more robust key distribution protocol but also establishes a solid theoretical foundation for enhancing the performance of RFI-MDI-QKD in hybrid channels.展开更多
Mode-pairing quantum key distribution(MP-QKD)is an excellent scheme that can exceed the repeaterless ratetransmittance bound without complex phase locking.Nevertheless,MP-QKD usually needs to ensure that the communica...Mode-pairing quantum key distribution(MP-QKD)is an excellent scheme that can exceed the repeaterless ratetransmittance bound without complex phase locking.Nevertheless,MP-QKD usually needs to ensure that the communication distances of the two channels are equal.To address the problem,the asymmetric MP-QKD protocol is proposed.In this paper,we enhance the performance of the asymmetric MP-QKD protocol based on the advantage distillation(AD)method without modifying the quantum process.The simulation results show that the AD method can extend the communication distance by about 70 km in the case of asymmetry.And we observe that as the misalignment error increases,the AD method further increases the expandable communication distance.Our work can further enhance the robustness and promote the practical application of the asymmetric MP-QKD.展开更多
Reference-frame-independent quantum key distribution(RFI-QKD)can avoid real-time calibration operation of reference frames and improve the efficiency of the communication process.However,due to imperfections of optica...Reference-frame-independent quantum key distribution(RFI-QKD)can avoid real-time calibration operation of reference frames and improve the efficiency of the communication process.However,due to imperfections of optical devices,there will inevitably exist intensity fluctuations in the source side of the QKD system,which will affect the final secure key rate.To reduce the influence of intensity fluctuations,an improved 3-intensity RFI-QKD scheme is proposed in this paper.After considering statistical fluctuations and implementing global parameter optimization,we conduct corresponding simulation analysis.The results show that our present work can present both higher key rate and a farther transmission distance than the standard method.展开更多
In the implementation of quantum key distribution,Security certification is a prerequisite for social deployment.Trans-mitters in decoy-BB84 systems typically employ gain-switched semiconductor lasers(GSSLs)to generat...In the implementation of quantum key distribution,Security certification is a prerequisite for social deployment.Trans-mitters in decoy-BB84 systems typically employ gain-switched semiconductor lasers(GSSLs)to generate optical pulses for encod-ing quantum information.However,the working state of the laser may violate the assumption of pulse independence.Here,we explored the dependence of intensity fluctuation and high-order correlation distribution of optical pulses on driving cur-rents at 2.5 GHz.We found the intensity correlation distribution had a significant dependence on the driving currents,which would affect the final key rate.By utilizing rate equations in our simulation,we confirmed the fluctuation and correlation origi-nated from the instability of gain-switched laser driven at a GHz-repetitive frequency.Finally,we evaluated the impact of inten-sity fluctuation on the secure key rate.This work will provide valuable insights for assessing whether the transmitter is operat-ing at optimal state in practice.展开更多
The advantage distillation(AD)technology has been proven to effectively improve the secret key rate and the communication distance of quantum key distribution(QKD).The mode-pairing quantum key distribution(MP-QKD)prot...The advantage distillation(AD)technology has been proven to effectively improve the secret key rate and the communication distance of quantum key distribution(QKD).The mode-pairing quantum key distribution(MP-QKD)protocol can overcome a fundamental physical limit,known as the Pirandola-Laurenza-Ottaviani-Banchi bound,without requiring global phase-locking.In this work,we propose a method based on multi-step AD to further enhance the performance of MP-QKD.The simulation results show that,compared to one-step AD,multi-step AD achieves better performance in long-distance scenarios and can tolerate a higher quantum bit error rate.Specifically,when the difference between the communication distances from Alice and Bob to Charlie is 25 km,50 km and 75 km,and the corresponding transmission distance exceeds 523 km,512 km and 496 km,respectively,the secret key rate achieved by multi-step AD surpasses that of one-step AD.Our findings indicate that the proposed method can effectively promote the application of MP-QKD in scenarios with high loss and high error rate.展开更多
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
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
In principle,the asynchronous measurement-device-independent quantum key distribution(AMDI-QKD)can surpass the key rate capacity without phase tracking and phase locking.However,practical imperfections in sources or d...In principle,the asynchronous measurement-device-independent quantum key distribution(AMDI-QKD)can surpass the key rate capacity without phase tracking and phase locking.However,practical imperfections in sources or detections would dramatically depress its performance.Here,we present an improved model on AMDI-QKD to reduce the influence of these imperfections,including intensity fluctuation,the afterpulse effect,and the dead time of detectors.Furthermore,we carry out corresponding numerical simulations.Simulation results show that,by implementing our present work,it can have more than 100 km longer secure transmission distance and one order of magnitude enhancement in the key generation rate after 320 km compared with the standard method.Moreover,our model can still break the Pirandola–Laurenza–Ottaviani–Banchi(PLOB)bound even under realistic experimental conditions.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 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
Trusted relays are the main state-of-the-art way to realize quantum key distribution networks.However,it is hard to require that all nodes in the network are fully trusted.In a multipath keytransmission mechanism,the ...Trusted relays are the main state-of-the-art way to realize quantum key distribution networks.However,it is hard to require that all nodes in the network are fully trusted.In a multipath keytransmission mechanism,the nodes can be weakly trusted because the secret key can be split into many parts and each part is transmitted to the receiver through a different path.However,if the capacity of a node’s quantum key pool is poorly designed,an attacker,Eve may eavesdrop on the communicating parties’secret message by initiating a redirection attack.In this paper,we show that Eve can trigger a cascading collapse effect by collapsing one of the edges in the network and forcing the communication parties to transmit the message through the nodes controlled by Eve.The influence of the traffic transfer ratio and the control parameters of the edge load on the breakdown probability of the edge are analyzed using a simulation.In order to effectively defend against the cascading attack,it is important for the designer to handle the relationship between the traffic and the capacity of the quantum key pool of each node in the network.展开更多
Combined with the dense coding mechanism and the bias-BB84 protocol,an efficient quantum key distribution protocol with dense coding on single photons(QDKD-SP)is proposed.Compared with the BB84 or bias-BB84 protocols ...Combined with the dense coding mechanism and the bias-BB84 protocol,an efficient quantum key distribution protocol with dense coding on single photons(QDKD-SP)is proposed.Compared with the BB84 or bias-BB84 protocols based on single photons,our QDKD-SP protocol has a higher capacity without increasing the difficulty of its experiment implementation as each correlated photon can carry two bits of useful information.Compared with the quantum dense key distribution(QDKD)protocol based on entangled states,our protocol is more feasible as the preparation and the measurement of a single-photon quantum state is not difficult with current technology.In addition,our QDKD-SP protocol is theoretically proved to be secure against the intercept-resend attack.展开更多
On basis of the nonlocality without entanglement proposed by Bennett,the properties of an orthogonal set of product states of two qutrits are revealed,i.e.,the transformation among different composite spaces can be re...On basis of the nonlocality without entanglement proposed by Bennett,the properties of an orthogonal set of product states of two qutrits are revealed,i.e.,the transformation among different composite spaces can be realized by using three unitary operations,and the correlation between two composite spaces is found.These properties can be used to quantum communication and quantum cryptography.As examples,we propose a scheme of controlled quantum secure direct communication and one of quantum key distribution.It is shown that applying the product state of qutrit to quantum information processing not only is of the advantages of large capacity and high efficiency,but ensures the security.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
基金funded by Youth Program of Shaanxi Provincial Department of Science and Technology(Grant No.2024JC-YBQN-0630)。
文摘Quantum key distribution(QKD)optical networks can provide more secure communications.However,with the increase of the QKD path requests and key updates,network blocking problems will become severe.The blocking problems in the network can become more severe because each fiber link has limited resources(such as wavelengths and time slots).In addition,QKD optical networks are also affected by external disturbances such as data interception and eavesdropping,resulting in inefficient network communication.In this paper,we exploit the idea of protection path to enhance the anti-interference ability of QKD optical network.By introducing the concept of security metric,we propose a routing wavelength and time slot allocation algorithm(RWTA)based on protection path,which can lessen the blocking problem of QKD optical network.According to simulation analysis,the security-metric-based RWTA algorithm(SM-RWTA)proposed in this paper can substantially improve the success rate of security key(SK)update and significantly reduce the blocking rate of the network.It can also improve the utilization rate of resources such as wavelengths and time slots.Compared with the non-security-metric-based RWTA algorithm(NSM-RWTA),our algorithm is robust and can enhance the anti-interference ability and security of QKD optical networks.
基金Project supported by the National Natural Science Foundation of China(Grant No.62375140)the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China(Grant No.KYCX241191 and SJCX250315)the Open Research Fund of the National Laboratory of Solid State Microstructures(Grant No.M36055)。
文摘A mode-pairing quantum key distribution based on heralded pair-coherent source with passive decoy-states is proposed,named HPCS-PDS-MP-QKD protocol,where the light sources at Alice and Bob sides are changed to heralded pair-coherent sources,and devices designed to implement passive decoy states are included at the transmitter sides to generate the decoy state pulses in the decoy-state window passively.With the defined efficient events and the designed pairing strategy,the key bits and bases can be obtained by data post-processing.Numerical simulation results verify the feasibility of the proposed protocol.The results show that the proposed protocol can exceed PLOB when the pairing interval setting is greater than 10^(3),and the transmission distance exceeds 200 km.When the key transmission distance reaches 300 km and the maximum pairing interval is equivalent to 1,its performance is improved by nearly 1.8 times compared to the original MP-QKD protocol with a weak coherent source(WCS-MP-QKD),and by 6.8 times higher than that of WCS-MPQKD with passive decoy states(WCS-PDS-MP-QKD).Meanwhile,the key transmission distance can reach 480 km,and surpasses the WCS-PDS-MP-QKD protocol by nearly 40 km.When the total pulse length is greater than 10^(11),the key generation rate is almost equal to that of infinite pulses.It is a promising QKD protocol that breaks the PLOB bound without requiring phase tracking and locking,has a longer transmission distance and a higher key generation rate,and eliminates the potential of side channel attack.
基金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 method for secure communication that utilizes quantum mechanics principles to distribute cryptographic keys between parties.Integrated photonics offer benefits such as compactness,scalability,energy efficiency and the potential for extensive integration.We have achieved BB84 phase encoding and decoding,time-bin phase QKD,and the coherent one-way(COW)protocol on a planar lightwave circuit(PLC)platform.At the optimal temperature,our chip successfully prepared quantum states,performed decoding and calculated the secure key rate of the time-bin phasedecoding QKD to be 80.46 kbps over a 20 km transmission with a quantum bit error rate(QBER)of 4.23%.The secure key rate of the COW protocol was 18.18 kbps,with a phase error rate of 3.627%and a time error rate of 0.377%.The uniqueness of this technology lies in its combination of high integration and protocol flexibility,providing an innovative solution for the development of future quantum communication networks.
文摘In the process of quantum key distribution(QKD), the communicating parties need to randomly determine quantum states and measurement bases. To ensure the security of key distribution, we aim to use true random sequences generated by true random number generators as the source of randomness. In practical systems, due to the difficulty of obtaining true random numbers, pseudo-random number generators are used instead. Although the random numbers generated by pseudorandom number generators are statistically random, meeting the requirements of uniform distribution and independence,they rely on an initial seed to generate corresponding pseudo-random sequences. Attackers may predict future elements from the initial elements of the random sequence, posing a security risk to quantum key distribution. This paper analyzes the problems existing in current pseudo-random number generators and proposes corresponding attack methods and applicable scenarios based on the vulnerabilities in the pseudo-random sequence generation process. Under certain conditions, it is possible to obtain the keys of the communicating parties with very low error rates, thus effectively attacking the quantum key system. This paper presents new requirements for the use of random numbers in quantum key systems, which can effectively guide the security evaluation of quantum key distribution protocols.
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)the Natural Science Foundation of Henan Province(Grant Nos.202300410534 and 202300410534)。
文摘The robustness of reference-frame-independent measurement-device-independent quantum key distribution(RFIMDI-QKD)against detection system vulnerabilities and its tolerance to reference frame drifts make it an ideal choice for hybrid channels.However,the impact of atmospheric turbulence on transmittance fluctuations remains a significant challenge for enhancing the performance of RFI-MDI-QKD.In this paper,we apply prefixed-threshold real-time selection and advantage distillation techniques to RFI-MDI-QKD in a hybrid channels scenario.Then,we analytically derive formulas for secret key rate in hybrid channels.Simulation results show that our modified scheme has apparent advances in both maximum tolerant loss and secure key rate compared to the fiber-only channel.Specifically,the result demonstrates that the maximum transmission distance can be improved by 15 km and 28 km when N=10^(12)and 10^(11).Our work not only provides a more robust key distribution protocol but also establishes a solid theoretical foundation for enhancing the performance of RFI-MDI-QKD in hybrid channels.
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(Grant Nos.202300410534 and 202300410532)the Anhui Initiative in Quantum Information Technologies.
文摘Mode-pairing quantum key distribution(MP-QKD)is an excellent scheme that can exceed the repeaterless ratetransmittance bound without complex phase locking.Nevertheless,MP-QKD usually needs to ensure that the communication distances of the two channels are equal.To address the problem,the asymmetric MP-QKD protocol is proposed.In this paper,we enhance the performance of the asymmetric MP-QKD protocol based on the advantage distillation(AD)method without modifying the quantum process.The simulation results show that the AD method can extend the communication distance by about 70 km in the case of asymmetry.And we observe that as the misalignment error increases,the AD method further increases the expandable communication distance.Our work can further enhance the robustness and promote the practical application of the asymmetric MP-QKD.
基金financial support from the Industrial Prospect and Key Core Technology Projects of Jiangsu Provincial Key R&D Program(Grant No.BE2022071)the Natural Science Foundation of Jiangsu Province(Grant No.BK20192001)+1 种基金the National Natural Science Foundation of China(Grant No.12074194)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.KYCX220954)。
文摘Reference-frame-independent quantum key distribution(RFI-QKD)can avoid real-time calibration operation of reference frames and improve the efficiency of the communication process.However,due to imperfections of optical devices,there will inevitably exist intensity fluctuations in the source side of the QKD system,which will affect the final secure key rate.To reduce the influence of intensity fluctuations,an improved 3-intensity RFI-QKD scheme is proposed in this paper.After considering statistical fluctuations and implementing global parameter optimization,we conduct corresponding simulation analysis.The results show that our present work can present both higher key rate and a farther transmission distance than the standard method.
基金support from the National Natural Science Foundation of China(62250710162).
文摘In the implementation of quantum key distribution,Security certification is a prerequisite for social deployment.Trans-mitters in decoy-BB84 systems typically employ gain-switched semiconductor lasers(GSSLs)to generate optical pulses for encod-ing quantum information.However,the working state of the laser may violate the assumption of pulse independence.Here,we explored the dependence of intensity fluctuation and high-order correlation distribution of optical pulses on driving cur-rents at 2.5 GHz.We found the intensity correlation distribution had a significant dependence on the driving currents,which would affect the final key rate.By utilizing rate equations in our simulation,we confirmed the fluctuation and correlation origi-nated from the instability of gain-switched laser driven at a GHz-repetitive frequency.Finally,we evaluated the impact of inten-sity fluctuation on the secure key rate.This work will provide valuable insights for assessing whether the transmitter is operat-ing at optimal state in practice.
基金supported by the National Natural Science Foundation of China(Grant Nos.62171144and 62031024)Guangxi Science Foundation(Grant Nos.2025GXNSFAA069137 and GXR-1BGQ2424005)Innovation Project of Guangxi Graduate Education(Grant No.YCBZ2025064)。
文摘The advantage distillation(AD)technology has been proven to effectively improve the secret key rate and the communication distance of quantum key distribution(QKD).The mode-pairing quantum key distribution(MP-QKD)protocol can overcome a fundamental physical limit,known as the Pirandola-Laurenza-Ottaviani-Banchi bound,without requiring global phase-locking.In this work,we propose a method based on multi-step AD to further enhance the performance of MP-QKD.The simulation results show that,compared to one-step AD,multi-step AD achieves better performance in long-distance scenarios and can tolerate a higher quantum bit error rate.Specifically,when the difference between the communication distances from Alice and Bob to Charlie is 25 km,50 km and 75 km,and the corresponding transmission distance exceeds 523 km,512 km and 496 km,respectively,the secret key rate achieved by multi-step AD surpasses that of one-step AD.Our findings indicate that the proposed method can effectively promote the application of MP-QKD in scenarios with high loss and high error rate.
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 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Project supported by Natural Science Foundation of Jiangsu Province(Grant Nos.BE2022071 and BK20192001)the National Natural Science Foundation of China(Grant Nos.12074194,62101285,62471248,and 12104240)Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.KYCX220954).
文摘In principle,the asynchronous measurement-device-independent quantum key distribution(AMDI-QKD)can surpass the key rate capacity without phase tracking and phase locking.However,practical imperfections in sources or detections would dramatically depress its performance.Here,we present an improved model on AMDI-QKD to reduce the influence of these imperfections,including intensity fluctuation,the afterpulse effect,and the dead time of detectors.Furthermore,we carry out corresponding numerical simulations.Simulation results show that,by implementing our present work,it can have more than 100 km longer secure transmission distance and one order of magnitude enhancement in the key generation rate after 320 km compared with the standard method.Moreover,our model can still break the Pirandola–Laurenza–Ottaviani–Banchi(PLOB)bound even under realistic experimental conditions.
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.
文摘Trusted relays are the main state-of-the-art way to realize quantum key distribution networks.However,it is hard to require that all nodes in the network are fully trusted.In a multipath keytransmission mechanism,the nodes can be weakly trusted because the secret key can be split into many parts and each part is transmitted to the receiver through a different path.However,if the capacity of a node’s quantum key pool is poorly designed,an attacker,Eve may eavesdrop on the communicating parties’secret message by initiating a redirection attack.In this paper,we show that Eve can trigger a cascading collapse effect by collapsing one of the edges in the network and forcing the communication parties to transmit the message through the nodes controlled by Eve.The influence of the traffic transfer ratio and the control parameters of the edge load on the breakdown probability of the edge are analyzed using a simulation.In order to effectively defend against the cascading attack,it is important for the designer to handle the relationship between the traffic and the capacity of the quantum key pool of each node in the network.
基金supported by the Natural Science Foundation of China under Grant No.11272120.
文摘Combined with the dense coding mechanism and the bias-BB84 protocol,an efficient quantum key distribution protocol with dense coding on single photons(QDKD-SP)is proposed.Compared with the BB84 or bias-BB84 protocols based on single photons,our QDKD-SP protocol has a higher capacity without increasing the difficulty of its experiment implementation as each correlated photon can carry two bits of useful information.Compared with the quantum dense key distribution(QDKD)protocol based on entangled states,our protocol is more feasible as the preparation and the measurement of a single-photon quantum state is not difficult with current technology.In addition,our QDKD-SP protocol is theoretically proved to be secure against the intercept-resend attack.
基金Supported by National Natural Sciences Foundation of China under Grant No.60667001
文摘On basis of the nonlocality without entanglement proposed by Bennett,the properties of an orthogonal set of product states of two qutrits are revealed,i.e.,the transformation among different composite spaces can be realized by using three unitary operations,and the correlation between two composite spaces is found.These properties can be used to quantum communication and quantum cryptography.As examples,we propose a scheme of controlled quantum secure direct communication and one of quantum key distribution.It is shown that applying the product state of qutrit to quantum information processing not only is of the advantages of large capacity and high efficiency,but ensures the security.
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.
