Phase-matching quantum-key distribution(PM-QKD)has achieved significant results in various practical applications.However,real-time communication requires dynamic adjustment and optimization of key parameters during c...Phase-matching quantum-key distribution(PM-QKD)has achieved significant results in various practical applications.However,real-time communication requires dynamic adjustment and optimization of key parameters during communication.In this letter,we predict the PM-QKD parameters using nature-inspired algorithms(NIAs).The results are obtained from an exhaustive traversal algorithm(ETA),which serves as a benchmark.We mainly study the parameter optimization effects of the two NIAs:ant colony optimization(ACO)and the genetic algorithm(GA).The configuration of the inherent parameters of these algorithms in the decoy-state PM-QKD is also discussed.The simulation results indicate that the parameters obtained by the ACO exhibit superior convergence and stability,whereas the GA results are relatively scattered.Nevertheless,more than 97%of the key rates predicted by both algorithms are highly consistent with the optimal key rate.Moreover,the relative error of the key rates remained below 10%.Furthermore,NIAs maintain power consumption below 8 W and require three orders of magnitude less computing time than ETA.展开更多
Using entanglement swapping of high-level Bell states, we first derive a covert layer between the secret message and the possible output results of the entanglement swapping between any two generalized Bell states, an...Using entanglement swapping of high-level Bell states, we first derive a covert layer between the secret message and the possible output results of the entanglement swapping between any two generalized Bell states, and then propose a novel high-efficiency quantum information hiding protocol based on the covert layer. In the proposed scheme, a covert channel can be built up under the cover of a high-level quantum secure direct communication （QSDC） channel for securely transmitting secret messages without consuming any auxiliary quantum state or any extra communication resource. It is shown that this protocol not only has a high embedding efficiency but also achieves a good imperceptibility as well as a high security.展开更多
In free space channel,continuous-variable quantum key distribution(CV-QKD)using polarized coherent-states can not only make the signal state more stable and less susceptible to interference based on the polarization n...In free space channel,continuous-variable quantum key distribution(CV-QKD)using polarized coherent-states can not only make the signal state more stable and less susceptible to interference based on the polarization non-sensitive of the free-space channel,but also reduce the noise introduced by phase interference.However,arbitrary continuous modulation can not be carried out in the past polarization coding,resulting in that the signal state can not obtain arbitrary continuous value in Poincare space,and the security analysis of CV-QKD using polarized coherent-states in free space is not complete.Here we propose a new modulation method to extend the modulation range of signal states with an optical-fiber-based polarization controller.In particular,in terms of the main influence factors in the free-space channel,we utilize the beam extinction and elliptical model when considering the transmittance and adopt the formulation of secret key rate.In addition,the performance of the proposed scheme under foggy weather is also taken into consideration to reveal the influence of severe weather.Numerical simulation shows that the proposed scheme is seriously affected by attenuation under foggy weather.The protocol fails when visibility is less than 1 km.At the same time,the wavelength can affect the performance of the proposed scheme.Specifically,under foggy weather,the longer the wavelength,the smaller the attenuation coefficient,and the better the transmission performance.Our proposed scheme can expand the modulation range of signal state,and supplement the security research of the scheme in the free-space channel,thus can provide theoretical support for subsequent experiments.展开更多
We propose a fully symmetrical QKD system that enables quantum states to be prepared and measured simultaneously without compromising system performance.Over a 25.6 km fiber channel,we demonstrate point-to-point QKD o...We propose a fully symmetrical QKD system that enables quantum states to be prepared and measured simultaneously without compromising system performance.Over a 25.6 km fiber channel,we demonstrate point-to-point QKD operations with asymmetric Mach–Zehnder interferometer modules.Two interference visibilities of above99%indicate that the proposed system has excellent stability.Consequently,the scheme not only improves the feasibility of distributing secret keys,but also enables QKD closer to more practical applications.展开更多
Block Adjustment(BA)is one of the essential techniques for producing high-precision geospatial 3D data products with optical stereo satellite imagery.For block adjustment with few ground-control points or without grou...Block Adjustment(BA)is one of the essential techniques for producing high-precision geospatial 3D data products with optical stereo satellite imagery.For block adjustment with few ground-control points or without ground control,the vertical error of the model is the decisive factor that constrains the accuracy of 3D data products.The elevation data obtained by spaceborne laser altimeter have the advantages of short update periods,high positioning precision,and low acquisition cost,providing sufficient data support for improving the elevation accuracy of stereo models through the combined BA.This paper proposes a geometric positioning model based on the integration of Optical Satellite Stereo Imagery(OSSI)and spaceborne laser altimeter data.Firstly,we elaborate the principle and necessity of this work through a literature review of existing methods.Then,the framework of our geo-positioning models.Secondly,four key technologies of the proposed model are expounded in order,including the acquisition and management of global Laser Control Points,the association of LCPs and OSSI,the block adjustment model combining LCPs with OSSI,and the accuracy estimation and quality control of the combined BA.Next,the combined BA experiment using Ziyuan-3(ZY-3)OSSI and ICESat-2 laser data was carried out at the testing site in Shandong Province,China.Experimental results prove that our method can automatically select LCPs with high accuracy.The elevation deviation of the combined BA eventually achieved the Mean Error(ME)of 0.06 m and the Root Mean Square Error(RMSE)of 1.18 m,much lower than the ME of 13.20 m and the RMSE of 3.88 m before the block adjustment.A further research direction will be how to perform more adequate accuracy analysis and quality control using massive laser points as checkpoints.展开更多
Leaf pigments are critical indicators of plant photosynthesis,stress,and physiological conditions.Inversion of radiative transfer models(RTMs)is a promising method for robustly retrieving leaf biochem-ical traits from...Leaf pigments are critical indicators of plant photosynthesis,stress,and physiological conditions.Inversion of radiative transfer models(RTMs)is a promising method for robustly retrieving leaf biochem-ical traits from canopy observations,and adding prior information has been effective in alleviating the“ill-posed”problem,a major challenge in model inversion.Canopy structure parameters,such as leaf area index(LAI)and average leaf inclination angle(ALA),can serve as prior information for leaf pigment retrie-val.Using canopy spectra simulated from the PROSAIL model,we estimated the effects of uncertainty in LAI and ALA used as prior information for lookup table-based inversions of leaf chlorophyll(C _(ab))and car-otenoid(C_(ar)).The retrieval accuracies of the two pigments were increased by use of the priors of LAI(RMSE of C_(ab) from 7.67 to 6.32μg cm^(-2),C_(ar) from 2.41 to 2.28μg cm^(-2))and ALA(RMSE of C_(ab) from 7.67 to 5.72μg cm^(-2),C_(ar) from 2.41 to 2.23μg cm^(-2)).However,this improvement deteriorated with an increase of additive and multiplicative uncertainties,and when 40% and 20% noise was added to LAI and ALA respectively,these priors ceased to increase retrieval accuracy.Validation using an experimental winter wheat dataset also showed that compared with C_(ar),the estimation accuracy of C_(ab) increased more or deteriorated less with uncertainty in prior canopy structure.This study demonstrates possible limita-tions of using prior information in RTM inversions for retrieval of leaf biochemistry,when large uncer-tainties are present.展开更多
This study applied a computerized parametric methodology to monitor, map, and quantify land degradation by salinization risk detection techniques at a 1：250 000 mapping scale using geo-information technology. The nor...This study applied a computerized parametric methodology to monitor, map, and quantify land degradation by salinization risk detection techniques at a 1：250 000 mapping scale using geo-information technology. The northern part of the Shaanxi province in China was taken as a case. Multi-temporal remotely sensed materials of both Landsat TM and thematic maps （ETM＋） were used as the bases to provide comprehensive views of surface conditions such as vegetation cover and salinization detection. With ERDAS ver. 9.1 software, the Normalized Differential Salinity Index （NDSl） and Salinity Index （S.I.） were computed and then evaluated for land degradation by salinization. Arc/Info ver. 9.2 software was used along with field observation data （GPS） for analysis. Using spatial analysis methods, results showed that 19 973.1 km^2 （72%） of land had no risk of land degradation by salinization, 3 684.7 km^2 （13%） had slight land degradation by salinization risk, 2 797.9 km^2 （10%） had moderate land degradation by salinization risk, and 1 218.9 km^2 （4%） of the total land area was at a high risk of land degradation by salinization. The study area, in general, is exposed to a high risk of soil salinization.展开更多
The application of χ state are investigated in remote state preparation （RSP）. By constructing useful measurement bases with the aid of Hurwitz matrix equation, we propose several RSP schemes of arbitrary two- and ...The application of χ state are investigated in remote state preparation （RSP）. By constructing useful measurement bases with the aid of Hurwitz matrix equation, we propose several RSP schemes of arbitrary two- and three-qubit states via the χ state as the entangled resource. It is shown that the original state can be successfully prepared with the probability 100% and 50% for real coefficients and complex coefficients, respectively. For the latter case, the special ensembles with unit success probability are discussed by the permutation group. It is worth mentioning that the novel measurement bases have no restrictions on the coefficients of the prepared state, which means that the proposed schemes are more applicable.展开更多
Recently, deterministic joint remote state preparation (JRSP) schemes have been proposed to achieve 100% success probability. In this paper, we propose a new version of deterministic JRSP scheme of an arbitrary two-qu...Recently, deterministic joint remote state preparation (JRSP) schemes have been proposed to achieve 100% success probability. In this paper, we propose a new version of deterministic JRSP scheme of an arbitrary two-qubit state by using the six-qubit cluster state as shared quantum resource. Compared with previous schemes, our scheme has high efficiency since less quantum resource is required, some additional unitary operations and measurements are unnecessary. We point out that the existing two types of deterministic JRSP schemes based on GHZ states and EPR pairs are equivalent.展开更多
Some important insights into the electron-states-architecture (ESA) and its dimensionality (from 3 to 0) in a semiconductor (or generally crystalline) material are obtained. The self-consistency of the set of density ...Some important insights into the electron-states-architecture (ESA) and its dimensionality (from 3 to 0) in a semiconductor (or generally crystalline) material are obtained. The self-consistency of the set of density of states (DOS) expressions with different dimensionalities is remediated through the clarification and rearrangement of the wave-function boundary conditions for working out the eigenvalues in the wave vector space. The actually too roughly observed and theoretically unpredicted critical points for the dimensionality transitions referring to the integer ones are revealed upon an unusual assumption of the intrinsic energy-level dispersion (ELD). The ELD based quantitative physical model had been established on an immediate instinct at the very beginning and has been properly modified afterwards. The uncertainty regarding the relationship between the de Broglie wavelength of electrons and the dimensionality transitions, seeming somewhat mysterious before, is consequentially eliminated. The effect of the material dimensions on the ELD width is also predicted and has been included in the model. The continuous evolution of the ESA dimensionality is convincingly and comprehensively interpreted and thus the area of the fractional ESA dimensionalities is opened. Another new assumption of the spatial extension shrinkage (SES) closely related to the ELD has also been made and thus the understanding of the behavior of an electron or, in a general sense, a particle has become more comprehensive. This work would manifest itself a new basis for further development of nanoheterostructures (or low dimensional heterostructures including the quantum wells, quantum wires, quantum dots and especially the hetero-dimensional structures). Expected should also be the possible inventions of some novel electronic and optoelectronic devices. More basically, it leads to a new quantum mechanical picture, the essential modifications of Schrödinger equation and Newtonian equation that give rise to a full cosmic-scope picture, and a super-low-speed relativity assumption.展开更多
An efficient quantum key distribution （QKD） protocol with orthogonal product states in the 3 3 Hilbert space is presented. The sender, Alice, disorders the orthogonal product state sequence and sends it to Bob. Aft...An efficient quantum key distribution （QKD） protocol with orthogonal product states in the 3 3 Hilbert space is presented. The sender, Alice, disorders the orthogonal product state sequence and sends it to Bob. After Alice has published the matching information of the particle sequence, Bob recovers the correct correspondences and makes an orthogonal measurement on the orthogonal product states to obtain the information sent by Alice. Finally, security analysis is also made.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
We present a （t, .n） threshold multiparty controlled quantum teleportation protocol of an arbitrary m-qubit quantum state between two remote parties. The unknown m-qubit quantum state can be recovered by the receive...We present a （t, .n） threshold multiparty controlled quantum teleportation protocol of an arbitrary m-qubit quantum state between two remote parties. The unknown m-qubit quantum state can be recovered by the receiver under control of a subset of the n controllers if the number of the subset is larger than or equal to a threshold, say, t, but not for any t - 1 or fewer controllers. Our scheme seems to be more practical and more flexible than other existing protocols. The quantum resource required is just m Einstein-Podolsky-Rosen （EPR） pairs plus some single photons. The techniques required are only Bell state measurement, single-qubit unitary operation and yon Neumann measurement. So our scheme is also feasible with present-day technique.展开更多
The ＇plug ＆ play＇ quantum key distribution system is the most stable and the earliest commercial system in the quantum communication field. Jones matrix and Jones calculus are widely used in the analysis of this sy...The ＇plug ＆ play＇ quantum key distribution system is the most stable and the earliest commercial system in the quantum communication field. Jones matrix and Jones calculus are widely used in the analysis of this system and the improved version, which is called the auto-compensating quantum key distribution system. Unfortunately, existing analysis has two drawbacks： only the auto-compensating process is analyzed and existing systems do not fully consider laser phase affected by a Faraday mirror （FM）. In this work, we present a detailed analysis of the output of light pulse transmitting in a plug ＆ play quantum key distribution system that contains only an FM, by Jones calculus. A similar analysis is made to a home-made auto-compensating system which contains two FMs to compensate for environmental effects. More importantly, we show that theoretical and experimental results are different in the plug ＆ play interferometric setup due to the fact that a conventional Jones matrix of FM neglected an additional phase π on alternative polarization direction. To resolve the above problem, we give a new Jones matrix of an FM according to the coordinate rotation. This new Jones matrix not only resolves the above contradiction in the plug ＆ play interferometric setup, but also is suitable for the previous analyses about auto-compensating quantum key distribution.展开更多
Real time phase regeneration is necessary for degraded phase modulation format optical communication systems. A regenerator based on the discrimitive gain effect of a semiconductor optical amplifier was proposed in re...Real time phase regeneration is necessary for degraded phase modulation format optical communication systems. A regenerator based on the discrimitive gain effect of a semiconductor optical amplifier was proposed in recent years. In this paper, for this type of regenerator, its optimal working condition is found by solving the dynamic equations which describe the variance of the optical field and carrier density in the semiconductor optical amplifier by the finite difference method. The results show that the optimal improvement of signal Q factor can reach more than 2.2 dB.展开更多
Quantum steganography that utilizes the quantum mechanical effect to achieve the purpose of information hiding is a popular topic of quantum information. Recently, E1 Allati et al. proposed a new quantum steganography...Quantum steganography that utilizes the quantum mechanical effect to achieve the purpose of information hiding is a popular topic of quantum information. Recently, E1 Allati et al. proposed a new quantum steganography using the GHZ4 state. Since all of the 8 groups of unitary transformations used in the secret message encoding rule change the GHZ4 state into 6 instead of 8 different quantum states when the global phase is not considered, we point out that a 2-bit instead of a 3-bit secret message can be encoded by one group of the given unitary transformations. To encode a 3-bit secret message by performing a group of unitary transformations on the GHZ4 state, we give another 8 groups of unitary transformations that can change the GHZ4 state into 8 different quantum states. Due to the symmetry of the GHZ4 state, all the possible 16 groups of unitary transformations change the GHZ4 state into 8 different quantum states, so the improved protocol achieves a high efficiency.展开更多
Reference-frame-independent quantum key distribution(RFI-QKD)can allow a quantum key distribution system to obtain the ideal key rate and transmission distance without reference system calibration,which has attracted ...Reference-frame-independent quantum key distribution(RFI-QKD)can allow a quantum key distribution system to obtain the ideal key rate and transmission distance without reference system calibration,which has attracted much attention.Here,we propose an RFI-QKD protocol based on wavelength division multiplexing(WDM)considering finite-key analysis and crosstalk.The finite-key bound for RFI-QKD with decoy states is derived under the crosstalk of WDM.The resulting secret key rate of RFI-QKD,which is more rigorous,is obtained.Simulation results reveal that the secret key rate of RFI-QKD based on WDM is affected by the multiplexing channel number,as well as crosstalk between adjacent channels.展开更多
An eavesdropper(Eve)can exploit all the imperfections of a practical quantum key distribution(QKD)system to obtain some information about the secret key,no matter whether these imperfections are from the physical laye...An eavesdropper(Eve)can exploit all the imperfections of a practical quantum key distribution(QKD)system to obtain some information about the secret key,no matter whether these imperfections are from the physical layer or from the post-processing layer.We propose a possible attack on a passive detection QKD system based on the imperfection from the software layer.The analysis shows that Eve can obtain all the information about the key without being discovered.展开更多
The quaternion approach to solve the coupled nonlinear Schrodinger equations （CNSEs） in fibers is proposed, converting the CNSEs to a single variable equation by using a conception of eigen-quaternion of coupled qua...The quaternion approach to solve the coupled nonlinear Schrodinger equations （CNSEs） in fibers is proposed, converting the CNSEs to a single variable equation by using a conception of eigen-quaternion of coupled quater- nion. The crosstalk of quarter-phase-shift-key signals caused by fiber nonlinearity in polarization multiplexing systems with 100 Cbps bit-rate is investigated and simulated. The results demonstrate that the crosstalk is like a rotated ghosting of input constellation. For the 50 km conventional fiber link, when the total power is less than 4roW, the crosstalk effect can be neglected; when the power is larger than 20roW, the crosstalk is very obvious. In addition, the crosstalk can not be detected according to the output eye diagram and state of polarization in Poincare sphere in the trunk fiber, making it difficult for the monitoring of optical trunk link.展开更多
Recently, Mao, Zhang, Wu et al. constructed two key exchange(KE) protocols based on tensor ergodic problem(TEP). Although they conjectured that these constructions can potentially resist quantum computing attack, they...Recently, Mao, Zhang, Wu et al. constructed two key exchange(KE) protocols based on tensor ergodic problem(TEP). Although they conjectured that these constructions can potentially resist quantum computing attack, they did not provide a rigorous security proof for their KE protocols. In this paper, applying the properties of ergodic matrix, we first present a polynomial time algorithm to solve the TEP problem using O(n^6) arithmetic operations in the finite field, where n is the security parameter. Then, applying this polynomial time algorithm, we generate a common shared key for two TEP-based KE constructions, respectively. In addition, we also provide a polynomial time algorithm with O(n^6) arithmetic operations that directly recovers the plaintext from a ciphertext for the KE-based encryption scheme. Thus, the TEP-based KE protocols and their corresponding encryption schemes are insecure.展开更多
基金supported by the State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications)No.IPOC2021ZT10BUPT Excellent Ph.D.Students Foundation(Grant No.CX2023207)the BUPT innovation and entrepreneurship support program No.2024-YC-A188。
文摘Phase-matching quantum-key distribution(PM-QKD)has achieved significant results in various practical applications.However,real-time communication requires dynamic adjustment and optimization of key parameters during communication.In this letter,we predict the PM-QKD parameters using nature-inspired algorithms(NIAs).The results are obtained from an exhaustive traversal algorithm(ETA),which serves as a benchmark.We mainly study the parameter optimization effects of the two NIAs:ant colony optimization(ACO)and the genetic algorithm(GA).The configuration of the inherent parameters of these algorithms in the decoy-state PM-QKD is also discussed.The simulation results indicate that the parameters obtained by the ACO exhibit superior convergence and stability,whereas the GA results are relatively scattered.Nevertheless,more than 97%of the key rates predicted by both algorithms are highly consistent with the optimal key rate.Moreover,the relative error of the key rates remained below 10%.Furthermore,NIAs maintain power consumption below 8 W and require three orders of magnitude less computing time than ETA.
基金supported by the National Natural Science Foundation of China(Grant Nos.61303199,61272514,61170272,61121061,and 61411146001)the Shandong Provincial Natural Science Foundation of China(Grant Nos.ZR2013FM025,ZR2013FQ001,and ZR2014FM003)+4 种基金the Shandong Provincial Outstanding Research Award Fund for Young Scientists of China(Grant Nos.BS2013DX010 and BS2014DX007)the Program for New Century Excellent Talents in Universities,China(Grant No.NCET-13-0681)the National Development Foundation for Cryptological Research,China(Grant No.MMJJ201401012)the Fok Ying Tong Education Foundation,China(Grant No.131067)the Shandong Academy of Sciences Youth Fund Project,China(Grant No.2013QN007)
文摘Using entanglement swapping of high-level Bell states, we first derive a covert layer between the secret message and the possible output results of the entanglement swapping between any two generalized Bell states, and then propose a novel high-efficiency quantum information hiding protocol based on the covert layer. In the proposed scheme, a covert channel can be built up under the cover of a high-level quantum secure direct communication （QSDC） channel for securely transmitting secret messages without consuming any auxiliary quantum state or any extra communication resource. It is shown that this protocol not only has a high embedding efficiency but also achieves a good imperceptibility as well as a high security.
基金the Key Program of the National Natural Science Foundation of China(Grant No.61531003)the National Natural Science Foundation of China(Grant No.62001041)+1 种基金China Postdoctoral Science Foundation(Grant No.2020TQ0016)the Fund of State Key Laboratory of Information Photonics and Optical Communications.
文摘In free space channel,continuous-variable quantum key distribution(CV-QKD)using polarized coherent-states can not only make the signal state more stable and less susceptible to interference based on the polarization non-sensitive of the free-space channel,but also reduce the noise introduced by phase interference.However,arbitrary continuous modulation can not be carried out in the past polarization coding,resulting in that the signal state can not obtain arbitrary continuous value in Poincare space,and the security analysis of CV-QKD using polarized coherent-states in free space is not complete.Here we propose a new modulation method to extend the modulation range of signal states with an optical-fiber-based polarization controller.In particular,in terms of the main influence factors in the free-space channel,we utilize the beam extinction and elliptical model when considering the transmittance and adopt the formulation of secret key rate.In addition,the performance of the proposed scheme under foggy weather is also taken into consideration to reveal the influence of severe weather.Numerical simulation shows that the proposed scheme is seriously affected by attenuation under foggy weather.The protocol fails when visibility is less than 1 km.At the same time,the wavelength can affect the performance of the proposed scheme.Specifically,under foggy weather,the longer the wavelength,the smaller the attenuation coefficient,and the better the transmission performance.Our proposed scheme can expand the modulation range of signal state,and supplement the security research of the scheme in the free-space channel,thus can provide theoretical support for subsequent experiments.
基金Supported by the Fundamental Research Funds for the Central Universities(Grant No.2019XD-A02)the State Key Laboratory of Information Photonics and Optical Communications,Beijing University of Posts and Telecommunications(Grant No.IPO2019ZT06)。
文摘We propose a fully symmetrical QKD system that enables quantum states to be prepared and measured simultaneously without compromising system performance.Over a 25.6 km fiber channel,we demonstrate point-to-point QKD operations with asymmetric Mach–Zehnder interferometer modules.Two interference visibilities of above99%indicate that the proposed system has excellent stability.Consequently,the scheme not only improves the feasibility of distributing secret keys,but also enables QKD closer to more practical applications.
基金supported by the National Science Fund for Distinguished Young Scholars[grant number 61825103]the Fundamental Research Funds for The Central Universities[grant number 2042022kf1002].
文摘Block Adjustment(BA)is one of the essential techniques for producing high-precision geospatial 3D data products with optical stereo satellite imagery.For block adjustment with few ground-control points or without ground control,the vertical error of the model is the decisive factor that constrains the accuracy of 3D data products.The elevation data obtained by spaceborne laser altimeter have the advantages of short update periods,high positioning precision,and low acquisition cost,providing sufficient data support for improving the elevation accuracy of stereo models through the combined BA.This paper proposes a geometric positioning model based on the integration of Optical Satellite Stereo Imagery(OSSI)and spaceborne laser altimeter data.Firstly,we elaborate the principle and necessity of this work through a literature review of existing methods.Then,the framework of our geo-positioning models.Secondly,four key technologies of the proposed model are expounded in order,including the acquisition and management of global Laser Control Points,the association of LCPs and OSSI,the block adjustment model combining LCPs with OSSI,and the accuracy estimation and quality control of the combined BA.Next,the combined BA experiment using Ziyuan-3(ZY-3)OSSI and ICESat-2 laser data was carried out at the testing site in Shandong Province,China.Experimental results prove that our method can automatically select LCPs with high accuracy.The elevation deviation of the combined BA eventually achieved the Mean Error(ME)of 0.06 m and the Root Mean Square Error(RMSE)of 1.18 m,much lower than the ME of 13.20 m and the RMSE of 3.88 m before the block adjustment.A further research direction will be how to perform more adequate accuracy analysis and quality control using massive laser points as checkpoints.
基金supported by the National Natural Science Foundation of China (41975044)the Open Research Fund of the State Laboratory of Information Engineering in Surveying,Mapping,Remote Sensing,Wuhan University (20R02)+2 种基金the Fundamental Research Funds for the Central Universities,China University of Geosciences (Wuhan)(111-G1323520290)funded by SNSA (Dnr 96/16)the EU-Aid funded CASSECS Project。
文摘Leaf pigments are critical indicators of plant photosynthesis,stress,and physiological conditions.Inversion of radiative transfer models(RTMs)is a promising method for robustly retrieving leaf biochem-ical traits from canopy observations,and adding prior information has been effective in alleviating the“ill-posed”problem,a major challenge in model inversion.Canopy structure parameters,such as leaf area index(LAI)and average leaf inclination angle(ALA),can serve as prior information for leaf pigment retrie-val.Using canopy spectra simulated from the PROSAIL model,we estimated the effects of uncertainty in LAI and ALA used as prior information for lookup table-based inversions of leaf chlorophyll(C _(ab))and car-otenoid(C_(ar)).The retrieval accuracies of the two pigments were increased by use of the priors of LAI(RMSE of C_(ab) from 7.67 to 6.32μg cm^(-2),C_(ar) from 2.41 to 2.28μg cm^(-2))and ALA(RMSE of C_(ab) from 7.67 to 5.72μg cm^(-2),C_(ar) from 2.41 to 2.23μg cm^(-2)).However,this improvement deteriorated with an increase of additive and multiplicative uncertainties,and when 40% and 20% noise was added to LAI and ALA respectively,these priors ceased to increase retrieval accuracy.Validation using an experimental winter wheat dataset also showed that compared with C_(ar),the estimation accuracy of C_(ab) increased more or deteriorated less with uncertainty in prior canopy structure.This study demonstrates possible limita-tions of using prior information in RTM inversions for retrieval of leaf biochemistry,when large uncer-tainties are present.
基金the Geo-information Science and Technology Program (No. IRT 0438)
文摘This study applied a computerized parametric methodology to monitor, map, and quantify land degradation by salinization risk detection techniques at a 1：250 000 mapping scale using geo-information technology. The northern part of the Shaanxi province in China was taken as a case. Multi-temporal remotely sensed materials of both Landsat TM and thematic maps （ETM＋） were used as the bases to provide comprehensive views of surface conditions such as vegetation cover and salinization detection. With ERDAS ver. 9.1 software, the Normalized Differential Salinity Index （NDSl） and Salinity Index （S.I.） were computed and then evaluated for land degradation by salinization. Arc/Info ver. 9.2 software was used along with field observation data （GPS） for analysis. Using spatial analysis methods, results showed that 19 973.1 km^2 （72%） of land had no risk of land degradation by salinization, 3 684.7 km^2 （13%） had slight land degradation by salinization risk, 2 797.9 km^2 （10%） had moderate land degradation by salinization risk, and 1 218.9 km^2 （4%） of the total land area was at a high risk of land degradation by salinization. The study area, in general, is exposed to a high risk of soil salinization.
基金supported by the National Natural Science Foundation of China(Grant Nos.61201253 and 61303039)the Fundamental Research Funds for the Central Universities of China(Grant No.2682014CX095)
文摘The application of χ state are investigated in remote state preparation （RSP）. By constructing useful measurement bases with the aid of Hurwitz matrix equation, we propose several RSP schemes of arbitrary two- and three-qubit states via the χ state as the entangled resource. It is shown that the original state can be successfully prepared with the probability 100% and 50% for real coefficients and complex coefficients, respectively. For the latter case, the special ensembles with unit success probability are discussed by the permutation group. It is worth mentioning that the novel measurement bases have no restrictions on the coefficients of the prepared state, which means that the proposed schemes are more applicable.
基金Supported by the National Natural Science Foundation of China under Grant Nos.61003287, 61272514, 61170272the Specialized Research Fund for the Doctoral Program of Higher Education under Grant No.20100005120002+1 种基金the Fok Ying Tong Education Foundation under Grant No.131067the Fundamental Research Funds for the Central Universities under Grant No.BUPT2012RC0221
文摘Recently, deterministic joint remote state preparation (JRSP) schemes have been proposed to achieve 100% success probability. In this paper, we propose a new version of deterministic JRSP scheme of an arbitrary two-qubit state by using the six-qubit cluster state as shared quantum resource. Compared with previous schemes, our scheme has high efficiency since less quantum resource is required, some additional unitary operations and measurements are unnecessary. We point out that the existing two types of deterministic JRSP schemes based on GHZ states and EPR pairs are equivalent.
基金supported by the National Basic Re-search Program of China(No.2010CB327601)the Na-tional Natural Science Foundation of China(No.61020106007,61108048)+1 种基金International Science&Technology Cooperation Program of China(No.2011DFR11010)the 111 Project(No.B07005).
文摘Some important insights into the electron-states-architecture (ESA) and its dimensionality (from 3 to 0) in a semiconductor (or generally crystalline) material are obtained. The self-consistency of the set of density of states (DOS) expressions with different dimensionalities is remediated through the clarification and rearrangement of the wave-function boundary conditions for working out the eigenvalues in the wave vector space. The actually too roughly observed and theoretically unpredicted critical points for the dimensionality transitions referring to the integer ones are revealed upon an unusual assumption of the intrinsic energy-level dispersion (ELD). The ELD based quantitative physical model had been established on an immediate instinct at the very beginning and has been properly modified afterwards. The uncertainty regarding the relationship between the de Broglie wavelength of electrons and the dimensionality transitions, seeming somewhat mysterious before, is consequentially eliminated. The effect of the material dimensions on the ELD width is also predicted and has been included in the model. The continuous evolution of the ESA dimensionality is convincingly and comprehensively interpreted and thus the area of the fractional ESA dimensionalities is opened. Another new assumption of the spatial extension shrinkage (SES) closely related to the ELD has also been made and thus the understanding of the behavior of an electron or, in a general sense, a particle has become more comprehensive. This work would manifest itself a new basis for further development of nanoheterostructures (or low dimensional heterostructures including the quantum wells, quantum wires, quantum dots and especially the hetero-dimensional structures). Expected should also be the possible inventions of some novel electronic and optoelectronic devices. More basically, it leads to a new quantum mechanical picture, the essential modifications of Schrödinger equation and Newtonian equation that give rise to a full cosmic-scope picture, and a super-low-speed relativity assumption.
基金Project supported by the National High Technology Development Program of China （Grant Nos 2006AA01Z419 and 2006AA01Z440）, the Major Program of the National Natural Science Foundation of China （Grant No 90604023）, the National Research Foundation for the Doctoral Program of Higher Education of China （Grant No 20040013007）, National Laboratory for Modern Communications Science Foundation of China （Grant No 9140C110101.0.601）.
文摘An efficient quantum key distribution （QKD） protocol with orthogonal product states in the 3 3 Hilbert space is presented. The sender, Alice, disorders the orthogonal product state sequence and sends it to Bob. After Alice has published the matching information of the particle sequence, Bob recovers the correct correspondences and makes an orthogonal measurement on the orthogonal product states to obtain the information sent by Alice. Finally, security analysis is also made.
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Supported by the National Basic Research Program of China (973 Program) under Grant No.2007CB311100the National Natural Science Foundation of China under Grant No.60873191+3 种基金the National High Technology Research and Development Program of China under Grant No.2006AA01Z419the Major Research plan of the National Natural Science Foundation of China under Grant No.90604023the Scientific Research Common Program of Beijing Municipal Commission of Education under Grant No.KM200810005004the Scientific Research Foundation for the Youth of Beijing University of Technology under Grant No.97007016200701
文摘We present a （t, .n） threshold multiparty controlled quantum teleportation protocol of an arbitrary m-qubit quantum state between two remote parties. The unknown m-qubit quantum state can be recovered by the receiver under control of a subset of the n controllers if the number of the subset is larger than or equal to a threshold, say, t, but not for any t - 1 or fewer controllers. Our scheme seems to be more practical and more flexible than other existing protocols. The quantum resource required is just m Einstein-Podolsky-Rosen （EPR） pairs plus some single photons. The techniques required are only Bell state measurement, single-qubit unitary operation and yon Neumann measurement. So our scheme is also feasible with present-day technique.
基金Supported by the National Natural Science Foundation of China under Grant No 61178010the Fund of State Key Laboratory of Information Photonics and Optical Communications of Beijing University of Posts and Telecommunications under Grant No201318the Fundamental Research Funds for the Central Universities of China under Grant No 2014TS01
文摘The ＇plug ＆ play＇ quantum key distribution system is the most stable and the earliest commercial system in the quantum communication field. Jones matrix and Jones calculus are widely used in the analysis of this system and the improved version, which is called the auto-compensating quantum key distribution system. Unfortunately, existing analysis has two drawbacks： only the auto-compensating process is analyzed and existing systems do not fully consider laser phase affected by a Faraday mirror （FM）. In this work, we present a detailed analysis of the output of light pulse transmitting in a plug ＆ play quantum key distribution system that contains only an FM, by Jones calculus. A similar analysis is made to a home-made auto-compensating system which contains two FMs to compensate for environmental effects. More importantly, we show that theoretical and experimental results are different in the plug ＆ play interferometric setup due to the fact that a conventional Jones matrix of FM neglected an additional phase π on alternative polarization direction. To resolve the above problem, we give a new Jones matrix of an FM according to the coordinate rotation. This new Jones matrix not only resolves the above contradiction in the plug ＆ play interferometric setup, but also is suitable for the previous analyses about auto-compensating quantum key distribution.
基金Project supported by the Scientific Fund for Chinese Universities (Grant No. BUPT 2011RC009)
文摘Real time phase regeneration is necessary for degraded phase modulation format optical communication systems. A regenerator based on the discrimitive gain effect of a semiconductor optical amplifier was proposed in recent years. In this paper, for this type of regenerator, its optimal working condition is found by solving the dynamic equations which describe the variance of the optical field and carrier density in the semiconductor optical amplifier by the finite difference method. The results show that the optimal improvement of signal Q factor can reach more than 2.2 dB.
基金supported by the National Natural Science Foundation of China (Grant Nos. 61170272,61272514,61003287,and 61070163)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20100005120002)+3 种基金the Fok Ying Tong Education Foundation (Grant No. 131067)the Natural Science Foundation of Shandong Province,China (Grant No. ZR2011FM023)the Outstanding Research Award Fund for Young Scientists of Shandong Province,China (Grant No. BS2011DX034)the Fundamental Research Funds for Central Universities of China (Grant No. BUPT2012RC0221)
文摘Quantum steganography that utilizes the quantum mechanical effect to achieve the purpose of information hiding is a popular topic of quantum information. Recently, E1 Allati et al. proposed a new quantum steganography using the GHZ4 state. Since all of the 8 groups of unitary transformations used in the secret message encoding rule change the GHZ4 state into 6 instead of 8 different quantum states when the global phase is not considered, we point out that a 2-bit instead of a 3-bit secret message can be encoded by one group of the given unitary transformations. To encode a 3-bit secret message by performing a group of unitary transformations on the GHZ4 state, we give another 8 groups of unitary transformations that can change the GHZ4 state into 8 different quantum states. Due to the symmetry of the GHZ4 state, all the possible 16 groups of unitary transformations change the GHZ4 state into 8 different quantum states, so the improved protocol achieves a high efficiency.
基金Project supported by the Fundamental Research Funds for the Central Universities,China(Grant No.2019XD-A02)the State Key Laboratory of Information Photonics and Optical Communications,Beijing University of Posts and Telecommunications(BUPT)(Grant No.IPOC2021ZT10)BUPT Innovation and Entrepreneurship Support Program(Grant No.2021-YC-A315).
文摘Reference-frame-independent quantum key distribution(RFI-QKD)can allow a quantum key distribution system to obtain the ideal key rate and transmission distance without reference system calibration,which has attracted much attention.Here,we propose an RFI-QKD protocol based on wavelength division multiplexing(WDM)considering finite-key analysis and crosstalk.The finite-key bound for RFI-QKD with decoy states is derived under the crosstalk of WDM.The resulting secret key rate of RFI-QKD,which is more rigorous,is obtained.Simulation results reveal that the secret key rate of RFI-QKD based on WDM is affected by the multiplexing channel number,as well as crosstalk between adjacent channels.
基金by the Natural Science Foundation of China under Grant Nos 60803156 and 61070215the Open Research Fund of State Key Laboratory of Information Security under Grant No 01-07.
文摘An eavesdropper(Eve)can exploit all the imperfections of a practical quantum key distribution(QKD)system to obtain some information about the secret key,no matter whether these imperfections are from the physical layer or from the post-processing layer.We propose a possible attack on a passive detection QKD system based on the imperfection from the software layer.The analysis shows that Eve can obtain all the information about the key without being discovered.
基金Supported by the National Natural Science Foundation of China under Grant No 61275075the Beijing Natural Science Foundation under Grant Nos 4132035 and 4144080
文摘The quaternion approach to solve the coupled nonlinear Schrodinger equations （CNSEs） in fibers is proposed, converting the CNSEs to a single variable equation by using a conception of eigen-quaternion of coupled quater- nion. The crosstalk of quarter-phase-shift-key signals caused by fiber nonlinearity in polarization multiplexing systems with 100 Cbps bit-rate is investigated and simulated. The results demonstrate that the crosstalk is like a rotated ghosting of input constellation. For the 50 km conventional fiber link, when the total power is less than 4roW, the crosstalk effect can be neglected; when the power is larger than 20roW, the crosstalk is very obvious. In addition, the crosstalk can not be detected according to the output eye diagram and state of polarization in Poincare sphere in the trunk fiber, making it difficult for the monitoring of optical trunk link.
基金supported by the National Natural Science Foundation of China(No.61672270,61602216,61702236)the Qing Lan Project for Young Researchers of Jiangsu Province of China(No.KYQ14004)+1 种基金the Open Fund of State Key Laboratory of Information Security,Institute of Information Engineering,Chinese Academy of Sciences(No.2015-MSB-10)Jiangsu Overseas Research&Training Program for University Prominent Young&Middle-aged Teachers and Presidents,Changzhou Sci&Tech Program,(Grant No.CJ20179027)
文摘Recently, Mao, Zhang, Wu et al. constructed two key exchange(KE) protocols based on tensor ergodic problem(TEP). Although they conjectured that these constructions can potentially resist quantum computing attack, they did not provide a rigorous security proof for their KE protocols. In this paper, applying the properties of ergodic matrix, we first present a polynomial time algorithm to solve the TEP problem using O(n^6) arithmetic operations in the finite field, where n is the security parameter. Then, applying this polynomial time algorithm, we generate a common shared key for two TEP-based KE constructions, respectively. In addition, we also provide a polynomial time algorithm with O(n^6) arithmetic operations that directly recovers the plaintext from a ciphertext for the KE-based encryption scheme. Thus, the TEP-based KE protocols and their corresponding encryption schemes are insecure.
