Dear Editor,The letter deals with the distributed state and fault estimation of the whole physical layer for cyber-physical systems(CPSs) when the cyber layer suffers from DoS attacks. With the advancement of embedded...Dear Editor,The letter deals with the distributed state and fault estimation of the whole physical layer for cyber-physical systems(CPSs) when the cyber layer suffers from DoS attacks. With the advancement of embedded computing, communication and related hardware technologies, CPSs have attracted extensive attention and have been widely used in power system, traffic network, refrigeration system and other fields.展开更多
In this paper,we present a distributed framework for the lidar-based relative state estimator which achieves highly accurate,real-time trajectory estimation of multiple Unmanned Aerial Vehicles(UAVs)in GPS-denied envi...In this paper,we present a distributed framework for the lidar-based relative state estimator which achieves highly accurate,real-time trajectory estimation of multiple Unmanned Aerial Vehicles(UAVs)in GPS-denied environments.The system builds atop a factor graph,and only on-board sensors and computing power are utilized.Benefiting from the keyframe strategy,each UAV performs relative state estimation individually and broadcasts very partial information without exchanging raw data.The complete system runs in real-time and is evaluated with three experiments in different environments.Experimental results show that the proposed distributed approach offers comparable performance with a centralized method in terms of accuracy and real-time performance.The flight test demonstrates that the proposed relative state estimation framework is able to be used for aggressive flights over 5 m/s.展开更多
This paper addresses the problem of distributed secure state estimation for multi-agent systems under homologous sensor attacks.Two types of secure Luenberger-like distributed observers are proposed to estimate the sy...This paper addresses the problem of distributed secure state estimation for multi-agent systems under homologous sensor attacks.Two types of secure Luenberger-like distributed observers are proposed to estimate the system state and attack signal simultaneously.Specifically,the proposed two observers are applicable to deal with the cases in the presence and absence of time delays during network communication.It is also shown that the proposed observers can ensure the attack estimations from different agents asymptotically converge to the same value.Sufficient conditions for guaranteeing the asymptotic convergence of the estimation errors are derived.Simulation examples are finally provided to demonstrate the effectiveness of the proposed results.展开更多
The quantum key distribution （QKD） allows two parties to share a secret key by typically making use of a one-way quantum channel. Howevery the two-way QKD has its own unique advantages, which means the two-way QKD h...The quantum key distribution （QKD） allows two parties to share a secret key by typically making use of a one-way quantum channel. Howevery the two-way QKD has its own unique advantages, which means the two-way QKD has become a focus recently. To improve the practieM performance of the two-way QKD, we present a security analysis of a two-way QKD protocol based on the decoy method with heralded single-photon sources （HSPSs）. We make use of two approaches to calculate the yield and the quantum bit error rate of single-photon and two-photon pulses. Then we present the secret key generation rate based on the GLLP formula. The numerical simulation shows that the protocol with HSPSs has an advantage in the secure distance compared with weak coherent state sources. In addition, we present the final secret key by considering the statistical fluctuation of the yield generation rate of the LM05 protocol with finite resources and the error rate.展开更多
A dynamic analysis approcach to investigate the state of load distribution among contact bearings of double circular are belical gears is proposed and a computer program is developed for calculating the factor of iced...A dynamic analysis approcach to investigate the state of load distribution among contact bearings of double circular are belical gears is proposed and a computer program is developed for calculating the factor of iced distribution based on the theory of W-N gears. The changing situations of load distribution among contact bearings of the gears influenced by main issues are analyzed by a series of parametric studies.展开更多
We investigate the decoy state quantum key distribution via the atmosphere channels. We consider the efficient decoy state method with one-signal state and two-decoy states. Our results show that the decoy state metho...We investigate the decoy state quantum key distribution via the atmosphere channels. We consider the efficient decoy state method with one-signal state and two-decoy states. Our results show that the decoy state method works even in the channels with fluctuating transmittance. Nevertheless, the key generation rate will be dra-matically decreased by atmosphere turbulence, which sheds more light on the characterization of atmosphere turbulence in realistic free-space based quantum key distributions.展开更多
This paper deals with the preblem of existence and uniqueness of the stationary distributions (abbr., s. d.'s) for the processes constructed in [4] .The main results are stated in § 1. For the reader's co...This paper deals with the preblem of existence and uniqueness of the stationary distributions (abbr., s. d.'s) for the processes constructed in [4] .The main results are stated in § 1. For the reader's convenience we first restate the existence theorems (Theorem 1 and 2) of the processes given in [4]. Then two existence theorems (Theorem 3 and 4) and a uniqueness theorem (Theorem 5) for the s. d.'s of the processes are presented. The last result (Theorem 6), as an application of the previous ones, is about the Schlgl model which comes from nonequilibrium statisticali physics. The details of the proofs of Theorem 3—6 are given in § 2—4.展开更多
The photon-added spin coherent state as a new kind of coherent state has been defined by iterated actions of the proper raising operator on the ordinary spin coherent state. In this paper, the quantum statistical prop...The photon-added spin coherent state as a new kind of coherent state has been defined by iterated actions of the proper raising operator on the ordinary spin coherent state. In this paper, the quantum statistical properties of photon-added spin coherent states such as photon number distribution, second-order correlation function and Wigner function are studied. It is found that the Wigner function shows the negativity in some regions and the second-order correlation function is less than unity. Therefore, the photon-added spin coherent state is a nonclassical state.展开更多
In this paper the fabrication technique of amorphous SnO2：（Zn, In） film is presented. The transmittance and gap-states distribution of the film are given. The experimental results of gap-states distribution are com...In this paper the fabrication technique of amorphous SnO2：（Zn, In） film is presented. The transmittance and gap-states distribution of the film are given. The experimental results of gap-states distribution are compared with the calculated results by using the facts of short range order and lattice vacancy defect of the gap states theory. The distribution of gap state has been proved to be discontinuous due to the short-range order of amorphous structure.展开更多
The branching ratios of ions and the angular distributions of electrons ejected from the Eu 4f^76p_（1/2）nd auto-ionizing states are investigated with the velocity-map-imaging technique.To populate the above auto-ion...The branching ratios of ions and the angular distributions of electrons ejected from the Eu 4f^76p_（1/2）nd auto-ionizing states are investigated with the velocity-map-imaging technique.To populate the above auto-ionizing states,the relevant bound Rydberg states have to be detected first.Two new bound Rydberg states are identified in the region between41150 cm^（-1）and 44580 cm^（-1）,from which auto-ionization spectra of the Eu 4f^76p_（1/2）nd states are observed with isolated core excitation method.With all preparations above,the branching ratios from the above auto-ionizing states to different final ionic states and the angular distributions of electrons ejected from these processes are measured systematically.Energy dependence of branching ratios and anisotropy parameters within the auto-ionization spectra are carefully analyzed,followed by a qualitative interpretation.展开更多
The distribution of the nuclear ground-state spin in a two-body random ensemble(TBRE)was studied using a general classification neural network(NN)model with two-body interaction matrix elements as input features and t...The distribution of the nuclear ground-state spin in a two-body random ensemble(TBRE)was studied using a general classification neural network(NN)model with two-body interaction matrix elements as input features and the corresponding ground-state spins as labels or output predictions.The quantum many-body system problem exceeds the capability of our optimized NNs in terms of accurately predicting the ground-state spin of each sample within the TBRE.However,our NN model effectively captured the statistical properties of the ground-state spin because it learned the empirical regularity of the ground-state spin distribution in TBRE,as discovered by physicists.展开更多
We measure the intensity of fluorescence spectral lines of Cs atoms in an electrodeless discharge lamp from visible light to the near-infrared region of 400-100Ohm. To build an excited state Faraday anomalous dispersi...We measure the intensity of fluorescence spectral lines of Cs atoms in an electrodeless discharge lamp from visible light to the near-infrared region of 400-100Ohm. To build an excited state Faraday anomalous dispersion optical filter, the population ratios between the excited states are calculated by rate equations and the spontaneous transition probabilities. The electrodeless discharge lamp with populations in the excited states can be used to realize the frequency stabilization reference for lasers at multiwavelength and the excited state Faraday anomalous dispersion optical filter for submarine communication applications in blue-green wavelengths to simplify the system.展开更多
Laser action in methyl methacrylate （MMA） co-doped with sulforhodamine B and crystal violet dyes was investi- gated. The dye mixture was incorporated into a solid polymeric matrix and was pumped by a 532-nm Nd：YAG ...Laser action in methyl methacrylate （MMA） co-doped with sulforhodamine B and crystal violet dyes was investi- gated. The dye mixture was incorporated into a solid polymeric matrix and was pumped by a 532-nm Nd：YAG laser. Distributed feedback dye laser （DFDL） action was induced in the dye mixture using a prism arrangement both in the donor and acceptor regions by an energy transfer mechanism. Theoretically, the characteristics of acceptor and donor DFDLs, and the dependence of their pulse widths and output powers on acceptor-donor concentrations and pump power, were studied. Experimentally, the output energy of DFDL was measured at the emission peaks of donor and acceptor dyes for different pump powers and different acceptor-donor concentrations. Tuning of the output wavelength was achieved by varying the period of the gain modulation of the laser medium. The laser wavelength showed continuous tunability from 563 nm to 648 nm.展开更多
We investigate the effect of collective-rotation noise on the security of the six-state quantum key distribution. We study the case where the eavesdropper, Eve, performs an intercept-resend attack on the quantum commu...We investigate the effect of collective-rotation noise on the security of the six-state quantum key distribution. We study the case where the eavesdropper, Eve, performs an intercept-resend attack on the quantum communication between Alice, the sender, and Bob, the receiver. We first derive the collective-rotation noise model for the six-state protocol and then parameterize the mutual information between Alice and Eve. We then derive quantum bit error rate for three interceptresend attack scenarios. We observe that the six-state protocol is robust against intercept-resend attacks on collective rotation noise channels when the rotation angle is kept within certain bounds.展开更多
We experimentally investigate the vibrational state distribution of the cations after carbon monoxide(CO)molecules are irradiated by strong laser fields.Vibrational-resolved fluorescent spectrum is observed,which can ...We experimentally investigate the vibrational state distribution of the cations after carbon monoxide(CO)molecules are irradiated by strong laser fields.Vibrational-resolved fluorescent spectrum is observed,which can be well assigned as the A^(2)Π(υ′=0-3)→X^(2)Σ+(υ″=0-3)transitions of the cations CO+,indicating the strong field ionization of the inner molecular orbital of CO.Relative distribution of vibrational states A^(2)Π(υ′=0-3)of CO+is retrieved from the measured spectrum and the Franck-Condon factors.It is found that the vibrational state distribution in strong field ionization of CO apparently deviates from the Franck-Condon-like distribution,but is in good agreement with the calculations,in which we include both the ionization rate and the overlapping between the vibrational wavefunctions of the neutral and cationic electronic states.The distribution of CO+(A^(2)Π,υ′)strongly depends on the laser intensity but is less dependent on the laser ellipticity.Analysis indicates the inter-nuclear distance-dependent ionization plays a significant role in the vibrational state distribution induced by strong field ionization of CO molecules.展开更多
We show that the secret key generation rate can be balanced with the maximum secure distance of four-state continuous-variable quantum key distribution（CV-QKD） by using the linear optics cloning machine（LOCM）. Ben...We show that the secret key generation rate can be balanced with the maximum secure distance of four-state continuous-variable quantum key distribution（CV-QKD） by using the linear optics cloning machine（LOCM）. Benefiting from the LOCM operation, the LOCM-tuned noise can be employed by the reference partner of reconciliation to achieve higher secret key generation rates over a long distance. Simulation results show that the LOCM operation can flexibly regulate the secret key generation rate and the maximum secure distance and improve the performance of four-state CV-QKD protocol by dynamically tuning parameters in an appropriate range.展开更多
Recently, a novel kind of quantum key distribution called the round-robin differential phase-shift （RRDPS） protocol was proposed, which bounds the amount of leakage without monitoring signal disturbance. The protoco...Recently, a novel kind of quantum key distribution called the round-robin differential phase-shift （RRDPS） protocol was proposed, which bounds the amount of leakage without monitoring signal disturbance. The protocol can be implemented by a weak coherent source. The security of this protocol with a simply characterized source has been proved. The application of a common phase shift can improve the secret key rate of the protocol. In practice, the randomized phase is discrete and the secret key rate is deviated from the continuous case. In this study, we analyze security of the RRDPS protocol with discrete-phase-randomized coherent state source and bound the secret key rate. We fix the length of each packet at 32 and 64, then simulate the secret key rates of the RRDPS protocol with discrete-phase randomization and continuous-phase randomization. Our simulation results show that the performance of the discrete-phase randomization case is close to the continuous counterpart with only a small number of discrete phases. The research is practically valuable for experimental implementation.展开更多
The ground and low-lying collective states of a rotating system of N=3 bosons harmonically confined in quasi-two-dimension and interacting via repulsive finite-range Gaussian potential is studied in weakly to moderate...The ground and low-lying collective states of a rotating system of N=3 bosons harmonically confined in quasi-two-dimension and interacting via repulsive finite-range Gaussian potential is studied in weakly to moderately interacting regime.The N-body Hamiltonian matrix is diagonalized in subspaces of quantized total angular momenta 0 ≤ L ≤ 4N to obtain the ground and low-lying eigenstates.Our numerical results show that breathing modes with N-body eigenenergy spacing of 2hω⊥,known to exist in strictly 2D system with zero-range(δ-function) interaction potential,may as well exist in quasi-2D system with finite-range Gaussian interaction potential.To gain an insight into the many-body states,the von Neumann entropy is calculated as a measure of quantum correlation and the conditional probability distribution is analyzed for the internal structure of the eigenstates.In the rapidly rotating regime the ground state in angular momentum subspaces L=(q/2)N(N-1) with q=2,4 is found to exhibit the anticorrelation structure suggesting that it may variationally be described by a Bose–Laughlin like state.We further observe that the first breathing mode exhibits features similar to the Bose–Laughlin state in having eigenenergy,von Neumann entropy and internal structure independent of interaction for the three-boson system considered here.On the contrary,for eigenstates lying between the Bose–Laughlin like ground state and the first breathing mode,values of eigenenergy,von Neumann entropy and internal structure are found to vary with interaction.展开更多
Considering that perfect channel state information(CSI) is difficult to obtain in practice,energy efficiency(EE) for distributed antenna systems(DAS) based on imperfect CSI and antennas selection is investigated in Ra...Considering that perfect channel state information(CSI) is difficult to obtain in practice,energy efficiency(EE) for distributed antenna systems(DAS) based on imperfect CSI and antennas selection is investigated in Rayleigh fading channel.A novel EE that is defined as the average transmission rate divided by the total consumed power is introduced.In accordance with this definition,an adaptive power allocation(PA) scheme for DAS is proposed to maximize the EE under the maximum transmit power constraint.The solution of PA in the constrained EE optimization does exist and is unique.A practical iterative algorithm with Newton method is presented to obtain the solution of PA.The proposed scheme includes the one under perfect CSI as a special case,and it only needs large scale and statistical information.As a result,the scheme has low overhead and good robustness.The theoretical EE is also derived for performance evaluation,and simulation result shows the validity of the theoretical analysis.Moreover,EE can be enhanced by decreasing the estimation error and/or path loss exponents.展开更多
基金supported by the National Natural Science Foundation of China(62303273,62373226)the National Research Foundation,Singapore through the Medium Sized Center for Advanced Robotics Technology Innovation(WP2.7)
文摘Dear Editor,The letter deals with the distributed state and fault estimation of the whole physical layer for cyber-physical systems(CPSs) when the cyber layer suffers from DoS attacks. With the advancement of embedded computing, communication and related hardware technologies, CPSs have attracted extensive attention and have been widely used in power system, traffic network, refrigeration system and other fields.
基金supported by the National Key Research and Development Program of China(No.2018AAA0102401)the National Natural Science Foundation of China(Nos.62022060,61773278,61873340).
文摘In this paper,we present a distributed framework for the lidar-based relative state estimator which achieves highly accurate,real-time trajectory estimation of multiple Unmanned Aerial Vehicles(UAVs)in GPS-denied environments.The system builds atop a factor graph,and only on-board sensors and computing power are utilized.Benefiting from the keyframe strategy,each UAV performs relative state estimation individually and broadcasts very partial information without exchanging raw data.The complete system runs in real-time and is evaluated with three experiments in different environments.Experimental results show that the proposed distributed approach offers comparable performance with a centralized method in terms of accuracy and real-time performance.The flight test demonstrates that the proposed relative state estimation framework is able to be used for aggressive flights over 5 m/s.
基金supported by the Fundamental Research Funds for the Central Universities(buctrc202201)High Performance Computing Platform,College of Information Science and Technology,Beijing University of Chemical Technology。
文摘This paper addresses the problem of distributed secure state estimation for multi-agent systems under homologous sensor attacks.Two types of secure Luenberger-like distributed observers are proposed to estimate the system state and attack signal simultaneously.Specifically,the proposed two observers are applicable to deal with the cases in the presence and absence of time delays during network communication.It is also shown that the proposed observers can ensure the attack estimations from different agents asymptotically converge to the same value.Sufficient conditions for guaranteeing the asymptotic convergence of the estimation errors are derived.Simulation examples are finally provided to demonstrate the effectiveness of the proposed results.
基金Supported by the National Basic Research Program of China under Grant No 2013CB338002the National Natural Science Foundation of China under Grant Nos 11304397 and 61505261
文摘The quantum key distribution （QKD） allows two parties to share a secret key by typically making use of a one-way quantum channel. Howevery the two-way QKD has its own unique advantages, which means the two-way QKD has become a focus recently. To improve the practieM performance of the two-way QKD, we present a security analysis of a two-way QKD protocol based on the decoy method with heralded single-photon sources （HSPSs）. We make use of two approaches to calculate the yield and the quantum bit error rate of single-photon and two-photon pulses. Then we present the secret key generation rate based on the GLLP formula. The numerical simulation shows that the protocol with HSPSs has an advantage in the secure distance compared with weak coherent state sources. In addition, we present the final secret key by considering the statistical fluctuation of the yield generation rate of the LM05 protocol with finite resources and the error rate.
文摘A dynamic analysis approcach to investigate the state of load distribution among contact bearings of double circular are belical gears is proposed and a computer program is developed for calculating the factor of iced distribution based on the theory of W-N gears. The changing situations of load distribution among contact bearings of the gears influenced by main issues are analyzed by a series of parametric studies.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11574400,U1304613,11204197,11204379 and 11074244the National Basic Research Program of China under Grant No 2011CBA00200the Doctor Foundation of the Ministry of Education of China under Grant No 20113402110059
文摘We investigate the decoy state quantum key distribution via the atmosphere channels. We consider the efficient decoy state method with one-signal state and two-decoy states. Our results show that the decoy state method works even in the channels with fluctuating transmittance. Nevertheless, the key generation rate will be dra-matically decreased by atmosphere turbulence, which sheds more light on the characterization of atmosphere turbulence in realistic free-space based quantum key distributions.
文摘This paper deals with the preblem of existence and uniqueness of the stationary distributions (abbr., s. d.'s) for the processes constructed in [4] .The main results are stated in § 1. For the reader's convenience we first restate the existence theorems (Theorem 1 and 2) of the processes given in [4]. Then two existence theorems (Theorem 3 and 4) and a uniqueness theorem (Theorem 5) for the s. d.'s of the processes are presented. The last result (Theorem 6), as an application of the previous ones, is about the Schlgl model which comes from nonequilibrium statisticali physics. The details of the proofs of Theorem 3—6 are given in § 2—4.
文摘The photon-added spin coherent state as a new kind of coherent state has been defined by iterated actions of the proper raising operator on the ordinary spin coherent state. In this paper, the quantum statistical properties of photon-added spin coherent states such as photon number distribution, second-order correlation function and Wigner function are studied. It is found that the Wigner function shows the negativity in some regions and the second-order correlation function is less than unity. Therefore, the photon-added spin coherent state is a nonclassical state.
基金Project supported by the Program A for Science and Technology of Education Bureau of Fujian Province of China (Grant No. JA08210)
文摘In this paper the fabrication technique of amorphous SnO2：（Zn, In） film is presented. The transmittance and gap-states distribution of the film are given. The experimental results of gap-states distribution are compared with the calculated results by using the facts of short range order and lattice vacancy defect of the gap states theory. The distribution of gap state has been proved to be discontinuous due to the short-range order of amorphous structure.
基金Project supported by the National Natural Science Foundation of China(Grant No.11174218)
文摘The branching ratios of ions and the angular distributions of electrons ejected from the Eu 4f^76p_（1/2）nd auto-ionizing states are investigated with the velocity-map-imaging technique.To populate the above auto-ionizing states,the relevant bound Rydberg states have to be detected first.Two new bound Rydberg states are identified in the region between41150 cm^（-1）and 44580 cm^（-1）,from which auto-ionization spectra of the Eu 4f^76p_（1/2）nd states are observed with isolated core excitation method.With all preparations above,the branching ratios from the above auto-ionizing states to different final ionic states and the angular distributions of electrons ejected from these processes are measured systematically.Energy dependence of branching ratios and anisotropy parameters within the auto-ionization spectra are carefully analyzed,followed by a qualitative interpretation.
基金supported by the National Natural Science Foundation of China Youth Fund(12105234)。
文摘The distribution of the nuclear ground-state spin in a two-body random ensemble(TBRE)was studied using a general classification neural network(NN)model with two-body interaction matrix elements as input features and the corresponding ground-state spins as labels or output predictions.The quantum many-body system problem exceeds the capability of our optimized NNs in terms of accurately predicting the ground-state spin of each sample within the TBRE.However,our NN model effectively captured the statistical properties of the ground-state spin because it learned the empirical regularity of the ground-state spin distribution in TBRE,as discovered by physicists.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11074011 and 91436210
文摘We measure the intensity of fluorescence spectral lines of Cs atoms in an electrodeless discharge lamp from visible light to the near-infrared region of 400-100Ohm. To build an excited state Faraday anomalous dispersion optical filter, the population ratios between the excited states are calculated by rate equations and the spontaneous transition probabilities. The electrodeless discharge lamp with populations in the excited states can be used to realize the frequency stabilization reference for lasers at multiwavelength and the excited state Faraday anomalous dispersion optical filter for submarine communication applications in blue-green wavelengths to simplify the system.
文摘Laser action in methyl methacrylate （MMA） co-doped with sulforhodamine B and crystal violet dyes was investi- gated. The dye mixture was incorporated into a solid polymeric matrix and was pumped by a 532-nm Nd：YAG laser. Distributed feedback dye laser （DFDL） action was induced in the dye mixture using a prism arrangement both in the donor and acceptor regions by an energy transfer mechanism. Theoretically, the characteristics of acceptor and donor DFDLs, and the dependence of their pulse widths and output powers on acceptor-donor concentrations and pump power, were studied. Experimentally, the output energy of DFDL was measured at the emission peaks of donor and acceptor dyes for different pump powers and different acceptor-donor concentrations. Tuning of the output wavelength was achieved by varying the period of the gain modulation of the laser medium. The laser wavelength showed continuous tunability from 563 nm to 648 nm.
基金Project supported by the South African Research Chair Initiative of the Department of Science and Technology and National Research Foundation
文摘We investigate the effect of collective-rotation noise on the security of the six-state quantum key distribution. We study the case where the eavesdropper, Eve, performs an intercept-resend attack on the quantum communication between Alice, the sender, and Bob, the receiver. We first derive the collective-rotation noise model for the six-state protocol and then parameterize the mutual information between Alice and Eve. We then derive quantum bit error rate for three interceptresend attack scenarios. We observe that the six-state protocol is robust against intercept-resend attacks on collective rotation noise channels when the rotation angle is kept within certain bounds.
基金supported by the National Key Program forS&TResearchand Development(No.2019YFA0307700)the National Natural Science Foundation of China(No.12174148,No.12274178,and No.12074144)the Natural Science Foundation of Jilin Province(No.20240101322JC).
文摘We experimentally investigate the vibrational state distribution of the cations after carbon monoxide(CO)molecules are irradiated by strong laser fields.Vibrational-resolved fluorescent spectrum is observed,which can be well assigned as the A^(2)Π(υ′=0-3)→X^(2)Σ+(υ″=0-3)transitions of the cations CO+,indicating the strong field ionization of the inner molecular orbital of CO.Relative distribution of vibrational states A^(2)Π(υ′=0-3)of CO+is retrieved from the measured spectrum and the Franck-Condon factors.It is found that the vibrational state distribution in strong field ionization of CO apparently deviates from the Franck-Condon-like distribution,but is in good agreement with the calculations,in which we include both the ionization rate and the overlapping between the vibrational wavefunctions of the neutral and cationic electronic states.The distribution of CO+(A^(2)Π,υ′)strongly depends on the laser intensity but is less dependent on the laser ellipticity.Analysis indicates the inter-nuclear distance-dependent ionization plays a significant role in the vibrational state distribution induced by strong field ionization of CO molecules.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61379153 and 61572529)
文摘We show that the secret key generation rate can be balanced with the maximum secure distance of four-state continuous-variable quantum key distribution（CV-QKD） by using the linear optics cloning machine（LOCM）. Benefiting from the LOCM operation, the LOCM-tuned noise can be employed by the reference partner of reconciliation to achieve higher secret key generation rates over a long distance. Simulation results show that the LOCM operation can flexibly regulate the secret key generation rate and the maximum secure distance and improve the performance of four-state CV-QKD protocol by dynamically tuning parameters in an appropriate range.
基金Supported by the National Basic Research Program of China under Grant No 2013CB338002the National Natural Science Foundation of China under Grant Nos 11304397 and 61505261
文摘Recently, a novel kind of quantum key distribution called the round-robin differential phase-shift （RRDPS） protocol was proposed, which bounds the amount of leakage without monitoring signal disturbance. The protocol can be implemented by a weak coherent source. The security of this protocol with a simply characterized source has been proved. The application of a common phase shift can improve the secret key rate of the protocol. In practice, the randomized phase is discrete and the secret key rate is deviated from the continuous case. In this study, we analyze security of the RRDPS protocol with discrete-phase-randomized coherent state source and bound the secret key rate. We fix the length of each packet at 32 and 64, then simulate the secret key rates of the RRDPS protocol with discrete-phase randomization and continuous-phase randomization. Our simulation results show that the performance of the discrete-phase randomization case is close to the continuous counterpart with only a small number of discrete phases. The research is practically valuable for experimental implementation.
文摘The ground and low-lying collective states of a rotating system of N=3 bosons harmonically confined in quasi-two-dimension and interacting via repulsive finite-range Gaussian potential is studied in weakly to moderately interacting regime.The N-body Hamiltonian matrix is diagonalized in subspaces of quantized total angular momenta 0 ≤ L ≤ 4N to obtain the ground and low-lying eigenstates.Our numerical results show that breathing modes with N-body eigenenergy spacing of 2hω⊥,known to exist in strictly 2D system with zero-range(δ-function) interaction potential,may as well exist in quasi-2D system with finite-range Gaussian interaction potential.To gain an insight into the many-body states,the von Neumann entropy is calculated as a measure of quantum correlation and the conditional probability distribution is analyzed for the internal structure of the eigenstates.In the rapidly rotating regime the ground state in angular momentum subspaces L=(q/2)N(N-1) with q=2,4 is found to exhibit the anticorrelation structure suggesting that it may variationally be described by a Bose–Laughlin like state.We further observe that the first breathing mode exhibits features similar to the Bose–Laughlin state in having eigenenergy,von Neumann entropy and internal structure independent of interaction for the three-boson system considered here.On the contrary,for eigenstates lying between the Bose–Laughlin like ground state and the first breathing mode,values of eigenenergy,von Neumann entropy and internal structure are found to vary with interaction.
基金partially supported by the National Natural Science Foundation of China(61571225,61271255,61232016,U1405254)the Open Foundation of Jiangsu Engineering Center of Network Monitoring(Nanjing University of Information Science and Technology)(Grant No.KJR1509)+2 种基金the PAPD fundthe CICAEET fundShenzhen Strategic Emerging Industry Development Funds(JSGG20150331160845693)
文摘Considering that perfect channel state information(CSI) is difficult to obtain in practice,energy efficiency(EE) for distributed antenna systems(DAS) based on imperfect CSI and antennas selection is investigated in Rayleigh fading channel.A novel EE that is defined as the average transmission rate divided by the total consumed power is introduced.In accordance with this definition,an adaptive power allocation(PA) scheme for DAS is proposed to maximize the EE under the maximum transmit power constraint.The solution of PA in the constrained EE optimization does exist and is unique.A practical iterative algorithm with Newton method is presented to obtain the solution of PA.The proposed scheme includes the one under perfect CSI as a special case,and it only needs large scale and statistical information.As a result,the scheme has low overhead and good robustness.The theoretical EE is also derived for performance evaluation,and simulation result shows the validity of the theoretical analysis.Moreover,EE can be enhanced by decreasing the estimation error and/or path loss exponents.
