The simultaneous transmitting and reflecting reconfigurable intelligent surface(STAR-RIS)can independently adjust surface’s reflection and transmission coefficients so as to enhance space coverage.For a multiple-inpu...The simultaneous transmitting and reflecting reconfigurable intelligent surface(STAR-RIS)can independently adjust surface’s reflection and transmission coefficients so as to enhance space coverage.For a multiple-input multiple-output(MIMO)communication system with a STAR-RIS,a base station(BS),an eavesdropper,and multiple users,the system security rate is studied.A joint design of the power allocation at the transmitter and phase shift matrices for reflection and transmission at the STAR-RIS is conducted,in order to maximize the worst achievable security data rate(ASDR).Since the problem is nonconvex and hence challenging,a particle swarm optimization(PSO)based algorithm is developed to tackle the problem.Both the cases of continuous and discrete phase shift matrices at the STAR-RIS are considered.Simulation results demonstrate the effectiveness of the proposed algorithm and shows the benefits of using STAR-RIS in MIMO mutliuser systems.展开更多
An optimization of device-to-device(D2D) security rate algorithm based on power control is provided to enhance the physical layer security underlaying D2D communication and guarantee the data rate requirement of the c...An optimization of device-to-device(D2D) security rate algorithm based on power control is provided to enhance the physical layer security underlaying D2D communication and guarantee the data rate requirement of the cellular user(CU) at the same time.First,a scenario model is set up,in which an eavesdropper is considered to wiretap the information of D2D transmitters.Then,a secure region of D2D communication is proposed.When D2D communication users reside outside the secure region,the spectrum of CU's is not allowed to share with the D2D communication so as to avoid eavesdropper tapping useful information of D2D communication.When D2D communication users reside inside the secure region,the security rate of D2D is maximized by optimization of the transmitting power of D2D and CU.The simulation results showthat the achieved D2D security rate of the proposed algorithm increases 2.8 bps/Hz when the signal to noise ratio(SNR) is 15 d B,compared with that when the random access algorithm is used.展开更多
Excessive nitrogen（N） fertilization in intensive agricultural areas such as the plain region of South China has resulted in low nitrogen use efficiency and serious environmental problems. To determine the optimum N ...Excessive nitrogen（N） fertilization in intensive agricultural areas such as the plain region of South China has resulted in low nitrogen use efficiency and serious environmental problems. To determine the optimum N application rate, grain yield, apparent nitrogen recovery efficiency（ANRE）, apparent N loss, and ammonium（NH_3） volatilization under different N application rates in the three years from 2012 to 2014 were studied. The results showed that the relationship between grain yields and N application rate in the three years were well fitted by quadratic equations. When N application rate reached 197 kg ha^（–1） in 2012, 199 kg ha^（–1） in 2013 and 196 kg ha^（–1） in 2014, the plateau of the grain yields appeared. With the increase of N application rate, the ANRE for rice decreased which could be expressed with sigmoidal equation; when N application rate was 305 kg ha^（–1） in 2012, 275 kg ha^（–1） in 2013 and 312 kg ha^（–1） in 2014, the curves of ANRE appeared turing points. Besides, the relationship between soil Nresidual and N application rate was fitted by the quadratic equation and the maximums of soil Nresidual were reached in the three years with the N application rate of 206, 244 and 170 kg ha^（–1）, respectively. Statistical analysis indicated that NH3 volatilization and apparent N loss in three years all increased with the increasing N application rate. When the amount of NH3 volatilization increased to 11.6 kg N ha^（–1） in 2012, 40.5 kg N ha^（–1） in 2013 and 57.0 kg N ha^（–1）in 2014, the apparent N loss in the three years had obvious increase. To determine the optimum N application rate, the average N application on the plateau of the grain yield was considered as the lower limit while the average N application rate at the turning points of ANRE, the residual N in soil and apparent N loss was taken as the upper limit. According to the results in three years, the optimum N application rate for rice in Zhejiang was 197–255 kg ha^（–1）.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
As one of the main application directions of quantum technology,underwater quantum communication is of great research significance.In order to study the influence of marine planktonic algal particles on the communicat...As one of the main application directions of quantum technology,underwater quantum communication is of great research significance.In order to study the influence of marine planktonic algal particles on the communication performance of underwater quantum links,based on the extinction characteristics of marine planktonic algal particles,the influence of changes in the chlorophyll concentration and particle number density of planktonic algal particles on the attenuation of underwater links is explored respectively,the influence of marine planktonic algal particles on the fidelity of underwater quantum links,the generation rate of the security key,and the utilization rate of the channel is analyzed,and simulation experiments are carried out.The results show that with the increase in chlorophyll concentration and particle density of aquatic planktonic algal particles,quantum communication channel link attenuation shows a gradually increasing trend.In addition,the security key generation rate,channel fidelity and utilization rate are gradually decreasing.Therefore,the performance of underwater quantum communication channel will be interfered by marine planktonic algal particles,and it is necessary to adjust the relevant parameter values in the quantum communication system according to different marine planktonic algal particle number density and chlorophyll concentration to improve the performance of quantum communication.展开更多
The secure key rate of quantum key distribution(QKD)is greatly reduced because of the untrusted devices.In this paper,to raise the secure key rate of QKD,a device-independent quantum key distribution(DIQKD)protocol is...The secure key rate of quantum key distribution(QKD)is greatly reduced because of the untrusted devices.In this paper,to raise the secure key rate of QKD,a device-independent quantum key distribution(DIQKD)protocol is proposed based on hyper-entangled states and Bell inequalities.The security of the protocol is analyzed against the individual attack by an adversary only limited by the no-signaling condition.Based on the formalization of Clauser-Horne Shimony-Holt(CHSH)violation measurement on local correlation,the probability of a secure secret bit is obtained,which is produced by a pair of hyper-entangled particles.By analyzing the secure secret bit,it is proven that,when both the polarization mode and the path mode contains entangled-states,the DIQKD protocol gets a better secure key rate than common Bell states.展开更多
With the widespread application of quantum communication technology,there is an urgent need to enhance unconditionally secure key rates and capacity.Measurement-device-independent quantum key distribution(MDI-QKD),pro...With the widespread application of quantum communication technology,there is an urgent need to enhance unconditionally secure key rates and capacity.Measurement-device-independent quantum key distribution(MDI-QKD),proven to be immune to detection-side channel attacks,is a secure and reliable quantum communication scheme.The core of this scheme is Hong–Ou–Mandle(HOM)interference,a quantum optical phenomenon with no classical analog,where identical photons meeting on a symmetric beam splitter(BS)undergo interference and bunching.Any differences in the degrees of freedom(frequency,arrival time,spectrum,polarization,and the average number of photons per pulse)between the photons will deteriorate the interference visibility.Here,we demonstrate 16-channel weak coherent pulses(WCPs)of HOM interference with all channels’interference visibility over 46%based on two independent frequency-post-aligned soliton microcombs(SMCs).In our experiment,full locking and frequency alignment of the comb teeth between the two SMCs were achieved through pump frequency stabilization,SMC repetition rate locking,and fine tuning of the repetition rate.This demonstrates the feasibility of using independently generated SMCs as multi-wavelength sources for quantum communication.Meanwhile,SMC can achieve hundreds of frequency-stable comb teeth by locking only two parameters,which further reduces the complexity of frequency locking and the need for finding sufficient suitable frequency references compared to independent laser arrays.展开更多
We investigate the resource allocation problem of a cell-free massive multiple-input multiple-output system under the condition of colluding eavesdropping by multiple passive eavesdroppers.To address the problem of li...We investigate the resource allocation problem of a cell-free massive multiple-input multiple-output system under the condition of colluding eavesdropping by multiple passive eavesdroppers.To address the problem of limited pilot resources,a scheme is proposed to allocate the pilot with the minimum pollution to users based on access point selection and optimize the pilot transmission power to improve the accuracy of channel estimation.Aiming at the secure transmission problem under a colluding eavesdropping environment by multiple passive eavesdroppers,based on the local partial zero-forcing precoding scheme,a transmission power optimization scheme is formulated to maximize the system’s minimum security spectral efficiency.Simulation results show that the proposed scheme can effectively reduce channel estimation error and improve system security.展开更多
The advent of quantum computers has significantly challenged the security of traditional cryptographic systems,prompting a surge in research on quantum key distribution(QKD).Among various QKD approaches,continuousvari...The advent of quantum computers has significantly challenged the security of traditional cryptographic systems,prompting a surge in research on quantum key distribution(QKD).Among various QKD approaches,continuousvariable QKD(CVQKD)offers superior resilience against background noise.However,the local local oscillator(LLO)CVQKD scheme faces substantial physical limitations in scenarios with high channel attenuation,and the large attenuation CVQKD remains unrealized.Bottleneck challenges include ensuring stable low-noise transmission and accurately estimating parameters under fluctuating channel conditions.We propose a continuousmode theoretical framework that provides an analytical method for time-varying quantum systems within a freespace channel.This framework can achieve high-fidelity LLO-CVQKD in free space without the need for complex,real-time frequency locking and transmittance calibration equipment.It can also enable free-space QKD under large attenuation and high repetition frequency.Through experimental validation,we first demonstrate high-rate secure quantum key distribution over high-loss free-space channels.Specifically,we achieve asymptotic key rates of 76.366 kbps and 403.896 kbps in 25 dB attenuation free-space channels without turbulence and 21.5 dB average attenuation free-space channels with turbulence,respectively.Additionally,we confirm the feasibility of experiments on mildly turbulent atmospheric channels spanning at least 10.5 km using current equipment.Our scheme provides direct insight into constructing an integrated air-ground quantum communication network.展开更多
文摘The simultaneous transmitting and reflecting reconfigurable intelligent surface(STAR-RIS)can independently adjust surface’s reflection and transmission coefficients so as to enhance space coverage.For a multiple-input multiple-output(MIMO)communication system with a STAR-RIS,a base station(BS),an eavesdropper,and multiple users,the system security rate is studied.A joint design of the power allocation at the transmitter and phase shift matrices for reflection and transmission at the STAR-RIS is conducted,in order to maximize the worst achievable security data rate(ASDR).Since the problem is nonconvex and hence challenging,a particle swarm optimization(PSO)based algorithm is developed to tackle the problem.Both the cases of continuous and discrete phase shift matrices at the STAR-RIS are considered.Simulation results demonstrate the effectiveness of the proposed algorithm and shows the benefits of using STAR-RIS in MIMO mutliuser systems.
基金National Natural Science Foundation of China(No.61503251)Natural Science Foundation of Shanghai,China(No.16ZR1424500)
文摘An optimization of device-to-device(D2D) security rate algorithm based on power control is provided to enhance the physical layer security underlaying D2D communication and guarantee the data rate requirement of the cellular user(CU) at the same time.First,a scenario model is set up,in which an eavesdropper is considered to wiretap the information of D2D transmitters.Then,a secure region of D2D communication is proposed.When D2D communication users reside outside the secure region,the spectrum of CU's is not allowed to share with the D2D communication so as to avoid eavesdropper tapping useful information of D2D communication.When D2D communication users reside inside the secure region,the security rate of D2D is maximized by optimization of the transmitting power of D2D and CU.The simulation results showthat the achieved D2D security rate of the proposed algorithm increases 2.8 bps/Hz when the signal to noise ratio(SNR) is 15 d B,compared with that when the random access algorithm is used.
基金supported by the National Natural Science Foundation of China(41501238)the Key Technologies R&D Program of China during the 12th Five-Year Plan period(2015BAD23B03)the Special Fund for Agro-scientific Research in the Public Interest from the Ministry of Agriculture,China(201003014-02-08)
文摘Excessive nitrogen（N） fertilization in intensive agricultural areas such as the plain region of South China has resulted in low nitrogen use efficiency and serious environmental problems. To determine the optimum N application rate, grain yield, apparent nitrogen recovery efficiency（ANRE）, apparent N loss, and ammonium（NH_3） volatilization under different N application rates in the three years from 2012 to 2014 were studied. The results showed that the relationship between grain yields and N application rate in the three years were well fitted by quadratic equations. When N application rate reached 197 kg ha^（–1） in 2012, 199 kg ha^（–1） in 2013 and 196 kg ha^（–1） in 2014, the plateau of the grain yields appeared. With the increase of N application rate, the ANRE for rice decreased which could be expressed with sigmoidal equation; when N application rate was 305 kg ha^（–1） in 2012, 275 kg ha^（–1） in 2013 and 312 kg ha^（–1） in 2014, the curves of ANRE appeared turing points. Besides, the relationship between soil Nresidual and N application rate was fitted by the quadratic equation and the maximums of soil Nresidual were reached in the three years with the N application rate of 206, 244 and 170 kg ha^（–1）, respectively. Statistical analysis indicated that NH3 volatilization and apparent N loss in three years all increased with the increasing N application rate. When the amount of NH3 volatilization increased to 11.6 kg N ha^（–1） in 2012, 40.5 kg N ha^（–1） in 2013 and 57.0 kg N ha^（–1）in 2014, the apparent N loss in the three years had obvious increase. To determine the optimum N application rate, the average N application on the plateau of the grain yield was considered as the lower limit while the average N application rate at the turning points of ANRE, the residual N in soil and apparent N loss was taken as the upper limit. According to the results in three years, the optimum N application rate for rice in Zhejiang was 197–255 kg ha^（–1）.
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.
基金funded by Youth Fund of the National Natural Science Foundation of China,grant number 11504176,61601230.
文摘As one of the main application directions of quantum technology,underwater quantum communication is of great research significance.In order to study the influence of marine planktonic algal particles on the communication performance of underwater quantum links,based on the extinction characteristics of marine planktonic algal particles,the influence of changes in the chlorophyll concentration and particle number density of planktonic algal particles on the attenuation of underwater links is explored respectively,the influence of marine planktonic algal particles on the fidelity of underwater quantum links,the generation rate of the security key,and the utilization rate of the channel is analyzed,and simulation experiments are carried out.The results show that with the increase in chlorophyll concentration and particle density of aquatic planktonic algal particles,quantum communication channel link attenuation shows a gradually increasing trend.In addition,the security key generation rate,channel fidelity and utilization rate are gradually decreasing.Therefore,the performance of underwater quantum communication channel will be interfered by marine planktonic algal particles,and it is necessary to adjust the relevant parameter values in the quantum communication system according to different marine planktonic algal particle number density and chlorophyll concentration to improve the performance of quantum communication.
基金This work is supported by NSFC(Grant Nos.61572086,61402058)the Application Foundation Project of Sichuan Province of China(Grant No.2017JY0168)+3 种基金the National Key Research and Development Program(No.2017YFB0802302)Sichuan innovation team of quantum security communication(No.17TD0009)Sichuan academic and technical leaders training funding support projects(No.2016120080102643)the Fund for Middle and Young Academic Leaders of CUIT(Grant No.J201511).
文摘The secure key rate of quantum key distribution(QKD)is greatly reduced because of the untrusted devices.In this paper,to raise the secure key rate of QKD,a device-independent quantum key distribution(DIQKD)protocol is proposed based on hyper-entangled states and Bell inequalities.The security of the protocol is analyzed against the individual attack by an adversary only limited by the no-signaling condition.Based on the formalization of Clauser-Horne Shimony-Holt(CHSH)violation measurement on local correlation,the probability of a secure secret bit is obtained,which is produced by a pair of hyper-entangled particles.By analyzing the secure secret bit,it is proven that,when both the polarization mode and the path mode contains entangled-states,the DIQKD protocol gets a better secure key rate than common Bell states.
基金Innovation Program for Quantum Science and Technology(2021ZD0300701,2021ZD0301500)CAS Project for Young Scientists in Basic Research(YSBR-069)+1 种基金National Natural Science Foundation of China(62075238,62205036)National Key Research and Development Program of China(2021YFB2800603)。
文摘With the widespread application of quantum communication technology,there is an urgent need to enhance unconditionally secure key rates and capacity.Measurement-device-independent quantum key distribution(MDI-QKD),proven to be immune to detection-side channel attacks,is a secure and reliable quantum communication scheme.The core of this scheme is Hong–Ou–Mandle(HOM)interference,a quantum optical phenomenon with no classical analog,where identical photons meeting on a symmetric beam splitter(BS)undergo interference and bunching.Any differences in the degrees of freedom(frequency,arrival time,spectrum,polarization,and the average number of photons per pulse)between the photons will deteriorate the interference visibility.Here,we demonstrate 16-channel weak coherent pulses(WCPs)of HOM interference with all channels’interference visibility over 46%based on two independent frequency-post-aligned soliton microcombs(SMCs).In our experiment,full locking and frequency alignment of the comb teeth between the two SMCs were achieved through pump frequency stabilization,SMC repetition rate locking,and fine tuning of the repetition rate.This demonstrates the feasibility of using independently generated SMCs as multi-wavelength sources for quantum communication.Meanwhile,SMC can achieve hundreds of frequency-stable comb teeth by locking only two parameters,which further reduces the complexity of frequency locking and the need for finding sufficient suitable frequency references compared to independent laser arrays.
基金supported by the National Natural Science Foundation of China(Nos.62071485,61671472,and 62271503)the Natural Science Foundation of Jiangsu Province,China(Nos.20201334 and 20181335)。
文摘We investigate the resource allocation problem of a cell-free massive multiple-input multiple-output system under the condition of colluding eavesdropping by multiple passive eavesdroppers.To address the problem of limited pilot resources,a scheme is proposed to allocate the pilot with the minimum pollution to users based on access point selection and optimize the pilot transmission power to improve the accuracy of channel estimation.Aiming at the secure transmission problem under a colluding eavesdropping environment by multiple passive eavesdroppers,based on the local partial zero-forcing precoding scheme,a transmission power optimization scheme is formulated to maximize the system’s minimum security spectral efficiency.Simulation results show that the proposed scheme can effectively reduce channel estimation error and improve system security.
基金Innovation Program for Quantum Science and Technology(2021ZD0300703)Shanghai Municipal Science and Technology Major Project(2019SHZDZX01)+1 种基金Key R&D Program of Guangdong Province(2020B0303040002)National Natural Science Foundation of China(62101320)。
文摘The advent of quantum computers has significantly challenged the security of traditional cryptographic systems,prompting a surge in research on quantum key distribution(QKD).Among various QKD approaches,continuousvariable QKD(CVQKD)offers superior resilience against background noise.However,the local local oscillator(LLO)CVQKD scheme faces substantial physical limitations in scenarios with high channel attenuation,and the large attenuation CVQKD remains unrealized.Bottleneck challenges include ensuring stable low-noise transmission and accurately estimating parameters under fluctuating channel conditions.We propose a continuousmode theoretical framework that provides an analytical method for time-varying quantum systems within a freespace channel.This framework can achieve high-fidelity LLO-CVQKD in free space without the need for complex,real-time frequency locking and transmittance calibration equipment.It can also enable free-space QKD under large attenuation and high repetition frequency.Through experimental validation,we first demonstrate high-rate secure quantum key distribution over high-loss free-space channels.Specifically,we achieve asymptotic key rates of 76.366 kbps and 403.896 kbps in 25 dB attenuation free-space channels without turbulence and 21.5 dB average attenuation free-space channels with turbulence,respectively.Additionally,we confirm the feasibility of experiments on mildly turbulent atmospheric channels spanning at least 10.5 km using current equipment.Our scheme provides direct insight into constructing an integrated air-ground quantum communication network.
