查看更多>>摘要：We investigate the effectiveness of entropic uncertainty,entanglement and steering in discerning quantum phase tran-sitions(QPTs).Specifically,we observe significant fluctuations in entropic uncertainty as the driving parameter traverses the phase transition point.It is observed that the entropic uncertainty,entanglement and quantum steering,based on the electron distribution probability,can serve as indicators for detecting QPTs.Notably,we reveal an intriguing anticorrelation relationship between entropic uncertainty and entanglement in the Aubry-André model.Moreover,we explore the feasi-bility of detecting a QPT when the period parameter is a rational number.These observations open up new and efficient avenues for probing QPTs.
查看更多>>摘要：In the domain of quantum cryptography,the implementation of quantum secret sharing stands as a pivotal element.In this paper,we propose a novel verifiable quantum secret sharing protocol using the d-dimensional product state and Lagrange interpolation techniques.This protocol is initiated by the dealer Alice,who initially prepares a quantum prod-uct state,selected from a predefined set of orthogonal product states within the Cd ⊗ Cd framework.Subsequently,the participants execute unitary operations on this product state to recover the underlying secret.Furthermore,we subject the protocol to a rigorous security analysis,considering both eavesdropping attacks and potential dishonesty from the partici-pants.Finally,we conduct a comparative analysis of our protocol against existing schemes.Our scheme exhibits economies of scale by exclusively employing quantum product states,thereby realizing significant cost-efficiency advantages.In terms of access structure,we adopt a(t,n)-threshold architecture,a strategic choice that augments the protocol's practicality and suitability for diverse applications.Furthermore,our protocol includes a rigorous integrity verification mechanism to ensure the honesty and reliability of the participants throughout the execution of the protocol.
查看更多>>摘要：In order to avoid the complexity of Gaussian modulation and the problem that the traditional point-to-point communi-cation DM-CVQKD protocol cannot meet the demand for multi-user key sharing at the same time,we propose a multi-ring discrete modulation continuous variable quantum key sharing scheme(MR-DM-CVQSS).In this paper,we primarily com-pare single-ring and multi-ring M-symbol amplitude and phase-shift keying modulations.We analyze their asymptotic key rates against collective attacks and consider the security key rates under finite-size effects.Leveraging the characteris-tics of discrete modulation,we improve the quantum secret sharing scheme.Non-dealer participants only require simple phase shifters to complete quantum secret sharing.We also provide the general design of the MR-DM-CVQSS protocol.We conduct a comprehensive analysis of the improved protocol's performance,confirming that the enhancement through multi-ring M-PSK allows for longer-distance quantum key distribution.Additionally,it reduces the deployment complexity of the system,thereby increasing the practical value.
查看更多>>摘要：Recently,a class of innovative notions on quantum network nonlocality(QNN),called full quantum network nonlocal-ity(FQNN),have been proposed in Phys.Rev.Lett.128 010403(2022).As the generalization of full network nonlocality(FNN),l-level quantum network nonlocality(l-QNN)was defined in arxiv.2306.15717 quant-ph(2024).FQNN is a NN that can be generated only from a network with all sources being non-classical.This is beyond the existing standard net-work nonlocality,which may be generated from a network with only a non-classical source.One of the challenging tasks is to establish corresponding Bell-like inequalities to demonstrate the FQNN or l-QNN.Up to now,the inequality criteria for FQNN and l-QNN have only been established for star and chain networks.In this paper,we devote ourselves to es-tablishing Bell-like inequalities for networks with more complex structures.Note that star and chain networks are special kinds of tree-shaped networks.We first establish the Bell-like inequalities for verifying l-QNN in k-forked tree-shaped networks.Such results generalize the existing inequalities for star and chain networks.Furthermore,we find the Bell-like inequality criteria for l-QNN for general acyclic and cyclic networks.Finally,we discuss the demonstration of l-QNN in the well-known butterfly networks.
查看更多>>摘要：The interconnection bottleneck caused by limitations of cable number,inner space and cooling power of dilution re-frigerators has been an outstanding challenge for building scalable superconducting quantum computers with the increasing number of qubits in quantum processors.To surmount such an obstacle,it is desirable to integrate qubits with quantum-classical interface(QCI)circuits based on rapid single flux quantum(RSFQ)circuits.In this work,a digital flux tuner for qubits(DFTQ)is proposed for manipulating flux of qubits as a crucial part of the interface circuit.A schematic diagram of the DFTQ is presented,consisting of a coarse tuning unit and a fine-tuning unit for providing magnetic flux with different precision to qubits.The method of using DFTQ to provide flux for gate operations is discussed from the optimization of circuit design and input signal.To verify the effectiveness of the method,simulations of a single DFTQ and quantum gates including a Z gate and an iSWAP gate with DFTQs are performed for flux-tunable transmons.The quantum process to-mography corresponding to the two gates is also carried out to analyze the sources of gate error.The results of tomography show that the gate fidelities independent of the initial states of the Z gate and the iSWAP gate are 99.935％and 99.676％,respectively.With DFTQs inside,the QCI would be a powerful tool for building large-scale quantum computers.
查看更多>>摘要：A non-Maxwellian collision kernel is employed to study the evolution of wealth distribution in a multi-agent society.The collision kernel divides agents into two different groups under certain conditions.Applying the kinetic theory of rarefied gases,we construct a two-group kinetic model for the evolution of wealth distribution.Under the continuous trading limit,the Fokker-Planck equation is derived and its steady-state solution is obtained.For the non-Maxwellian collision kernel,we find a suitable redistribution operator to match the taxation.Our results illustrate that taxation and redistribution have the property to change the Pareto index.
查看更多>>摘要：A novel color image encryption scheme is developed to enhance the security of encryption without increasing the complexity.Firstly,the plain color image is decomposed into three grayscale plain images,which are converted into the frequency domain coefficient matrices(FDCM)with discrete cosine transform(DCT)operation.After that,a two-dimensional(2D)coupled chaotic system is developed and used to generate one group of embedded matrices and another group of encryption matrices,respectively.The embedded matrices are integrated with the FDCM to fulfill the frequency domain encryption,and then the inverse DCT processing is implemented to recover the spatial domain signal.Eventually,under the function of the encryption matrices and the proposed diagonal scrambling algorithm,the final color ciphertext is obtained.The experimental results show that the proposed method can not only ensure efficient encryption but also satisfy various sizes of image encryption.Besides,it has better performance than other similar techniques in statistical feature analysis,such as key space,key sensitivity,anti-differential attack,information entropy,noise attack,etc.
查看更多>>摘要：In recent years,the traffic congestion problem has become more and more serious,and the research on traffic system control has become a new hot spot.Studying the bifurcation characteristics of traffic flow systems and designing control schemes for unstable pivots can alleviate the traffic congestion problem from a new perspective.In this work,the full-speed differential model considering the vehicle network environment is improved in order to adjust the traffic flow from the perspective of bifurcation control,the existence conditions of Hopf bifurcation and saddle-node bifurcation in the model are proved theoretically,and the stability mutation point for the stability of the transportation system is found.For the unstable bifurcation point,a nonlinear system feedback controller is designed by using Chebyshev polynomial approximation and stochastic feedback control method.The advancement,postponement,and elimination of Hopf bifurcation are achieved without changing the system equilibrium point,and the mutation behavior of the transportation system is controlled so as to alleviate the traffic congestion.The changes in the stability of complex traffic systems are explained through the bifurcation analysis,which can better capture the characteristics of the traffic flow.By adjusting the control parameters in the feedback controllers,the influence of the boundary conditions on the stability of the traffic system is adequately described,and the effects of the unstable focuses and saddle points on the system are suppressed to slow down the traffic flow.In addition,the unstable bifurcation points can be eliminated and the Hopf bifurcation can be controlled to advance,delay,and disappear,so as to realize the control of the stability behavior of the traffic system,which can help to alleviate the traffic congestion and describe the actual traffic phenomena as well.
查看更多>>摘要：Realization of high performance satellite onboard clock is vital for various positioning,navigation,and timing ap-plications.For further improvement of the synchronization-based satellite time and frequency references,we propose a geosynchronous(GEO)satellite virtual clock concept based on ground-satellite synchronization and present a beacon transponder structure for its implementation(scheduled for launch in 2025),which does not require atomic clocks to be mounted on the satellite.Its high performance relies only on minor modifications to the existing transponder structure of GEO satellites.We carefully model the carrier phase link and analyze the factors causing link asymmetry within the special relativity.Considering that performance of such synchronization-based satellite clocks is primarily limited by the link's random phase noise,which cannot be adequately modeled,we design a closed-loop experiment based on commercial GEO satellites for pre-evaluation.This experiment aims at extracting the zero-means random part of the ground-satellite Ku-band carrier phase via a feedback loop.Ultimately,we obtain a 1σ value of 0.633 ps(two-way link),following the Gaussian distribution.From this result,we conclude that the proposed real-time Einstein-synchronization-defined satellite virtual clock can achieve picosecond-level replication of onboard time and frequency.
查看更多>>摘要：Although phase separation is a ubiquitous phenomenon,the interactions between multiple components make it diffi-cult to accurately model and predict.In recent years,machine learning has been widely used in physics simulations.Here,we present a physical information-enhanced graph neural network(PIENet)to simulate and predict the evolution of phase separation.The accuracy of our model in predicting particle positions is improved by 40.3％and 51.77％compared with CNN and SVM respectively.Moreover,we design an order parameter based on local density to measure the evolution of phase separation and analyze the systematic changes with different repulsion coefficients and different Schmidt numbers.The results demonstrate that our model can achieve long-term accurate predictions of order parameters without requiring complex handcrafted features.These results prove that graph neural networks can become new tools and methods for predicting the structure and properties of complex physical systems.
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