查看更多>>摘要：Topological magnetism with strong robustness,nanoscale dimensions and ultralow driving current density(～106 A/m2)is promising for applications in information sensing,storage,and processing,and thus sparking widespread research interest.Exploring candidate material systems with nanoscale size and easily tunable properties is a key for re-alizing practical topological magnetism-based spintronic devices.Here,we propose a class of ultrathin heterostructures,Fe/Bi2O2X(X=S,Se,Te)by deposing metal Fe on quasi-two-dimensional(2D)bismuth oxychalcogenides Bi2O2X(X=S,Se,Te)with excellent ferroelectric/ferroelastic properties.Large Dzyaloshinskii-Moriya interaction(DMI)and topological magnetism can be realized.Our atomistic spin dynamics simulations demonstrate that field-free vortex-antivortex loops and sub-10 nm skyrmions exist in Fe/Bi2O2S and Fe/Bi2O2Se interfaces,respectively.These results provide a possible strategy to tailor topological magnetism in ultrathin magnets/2D materials interfaces,which is extremely vital for spintronics applications.
查看更多>>摘要：The Riemann-Hilbert approach is demonstrated to investigate the defocusing Lakshmanan-Porsezian-Daniel equa-tion under fully asymmetric nonzero boundary conditions.In contrast to the symmetry case,this paper focuses on the branch points related to the scattering problem rather than using the Riemann surfaces.For the direct problem,we analyze the Jost solution of lax pairs and some properties of scattering matrix,including two kinds of symmetries.The inverse prob-lem at branch points can be presented,corresponding to the associated Riemann-Hilbert.Moreover,we investigate the time evolution problem and estimate the value of solving the solutions by Jost function.For the inverse problem,we construct it as a Riemann-Hilbert problem and formulate the reconstruction formula for the defocusing Lakshmanan-Porsezian-Daniel equation.The solutions of the Riemann-Hilbert problem can be constructed by estimating the solutions.Finally,we work out the solutions under fully asymmetric nonzero boundary conditions precisely via utilizing the Sokhotski-Plemelj formula and the square of the negative column transformation with the assistance of Riemann surfaces.These results are valuable for understanding physical phenomena and developing further applications of optical problems.
查看更多>>摘要：We investigate the topological phase transition in the Su-Schrieffer-Heeger model with the long-range hopping and quasi-periodic modulation.By numerically calculating the real-space winding number,we obtain topological phase dia-grams for different disordered structures.These diagrams suggest that topological phase transitions are different by select-ing the specific disordered structure.When quasi-periodic modulation is applied to intracell hopping,the resulting disorder induces topological Anderson insulator(TAI)phase with high winding number(W=2),but the topological states are de-stroyed as the disorder increases.Conversely,when intercell hoppings are modulated quasi-periodically,both TAI phase and the process of destruction and restoration of topological zero modes can be induced by disorder.These topological states remain robust even under strong disorder conditions.Our work demonstrates that disorder effects do not always disrupt topological states;rather,with a judicious selection of disordered structures,topological properties can be preserved.
查看更多>>摘要：Social networks are inevitably subject to disruptions from the physical world,such as sudden internet outages that sever local connections and impede information flow.While Gaussian white noise,commonly used to simulate stochastic disruptions,only fluctuates within a narrow range around its mean and fails to capture large-scale variations,Lévy noise can effectively compensate for this limitation.Therefore,a susceptible-infected-removed rumor propagation model with Lévy noise is constructed on homogeneous and heterogeneous networks,respectively.Then,the existence of a global positive solution and the asymptotic path-wise of the solution are derived on heterogeneous networks,and the sufficient conditions of rumor extinction and persistence are investigated.Subsequently,theoretical results are verified through numerical cal-culations and the sensitivity analysis related to the threshold is conducted on the model parameters.Through simulation experiments on Watts-Strogatz(WS)and Barabási-Albert networks,it is found that the addition of noise can inhibit the spread of rumors,resulting in a stochastic resonance phenomenon,and the optimal noise intensity is obtained on the WS network.The validity of the model is verified on three real datasets by particle swarm optimization algorithm.
查看更多>>摘要：In the realm of public goods game,punishment,as a potent tool,stands out for fostering cooperation.While it effectively addresses the first-order free-rider problem,the associated costs can be substantial.Punishers incur expenses in imposing sanctions,while defectors face fines.Unfortunately,these monetary elements seemingly vanish into thin air,representing a loss to the system itself.However,by virtue of the redistribution of fines to cooperators and punishers,not only can we mitigate this loss,but the rewards for these cooperative individuals can be enhanced.Based upon this premise,this paper introduces a fine distribution mechanism to the traditional pool punishment model.Under identical parameter settings,by conducting a comparative experiment with the conventional punishment model,the paper aims to investigate the impact of fine distribution on the evolution of cooperation in spatial public goods game.The experimental results clearly demonstrate that,in instances where the punishment cost is prohibitively high,the cooperative strategies of the traditional pool punishment model may completely collapse.However,the model enriched with fine distribution manages to sustain a considerable number of cooperative strategies,thus highlighting its effectiveness in promoting and preserving cooperation,even in the face of substantial punishment cost.
查看更多>>摘要：In public goods games,punishments and rewards have been shown to be effective mechanisms for maintaining indi-vidual cooperation.However,punishments and rewards are costly to incentivize cooperation.Therefore,the generation of costly penalties and rewards has been a complex problem in promoting the development of cooperation.In real society,specialized institutions exist to punish evil people or reward good people by collecting taxes.We propose a strong altruistic punishment or reward strategy in the public goods game through this phenomenon.Through theoretical analysis and nu-merical calculation,we can get that tax-based strong altruistic punishment(reward)has more evolutionary advantages than traditional strong altruistic punishment(reward)in maintaining cooperation and tax-based strong altruistic reward leads to a higher level of cooperation than tax-based strong altruistic punishment.
查看更多>>摘要：We adopt a floor field cellular automata model to study the statistical properties of bidirectional pedestrian flow mov-ing in a straight corridor.We introduce a game-theoretic framework to deal with the conflict of multiple pedestrians trying to move to the same target location.By means of computer simulations,we show that the complementary cumulative distri-bution of the time interval between two consecutive pedestrians leaving the corridor can be fitted by a stretched exponential distribution,and surprisingly,the statistical properties of the two types of pedestrian flows are affected differently by the flow ratio,i.e.,the ratio of the pedestrians walking toward different directions.We also find that the jam probability exhibits a non-monotonic behavior with the flow ratio,where the worst performance arises at an intermediate flow ratio of around 0.2.Our simulation results are consistent with some empirical observations,which suggest that the peculiar characteristics of the pedestrians may attributed to the anticipation mechanism of collision avoidance.
查看更多>>摘要：We study the dynamics of fundamental and double-pole breathers and solitons for the focusing and defocusing non-linear Schrödinger equation with the sextic operator under non-zero boundary conditions.Our analysis mainly focuses on the dynamical properties of simple-and double-pole solutions.Firstly,through verification,we find that solutions under non-zero boundary conditions can be transformed into solutions under zero boundary conditions,whether in simple-pole or double-pole cases.For the focusing case,in the investigation of simple-pole solutions,temporal periodic breather and the spatial-temporal periodic breather are obtained by modulating parameters.Additionally,in the case of multi-pole solitons,we analyze parallel-state solitons,bound-state solitons,and intersecting solitons,providing a brief analysis of their interac-tions.In the double-pole case,we observe that the two solitons undergo two interactions,resulting in a distinctive"triangle"crest.Furthermore,for the defocusing case,we briefly consider two situations of simple-pole solutions,obtaining one and two dark solitons.
查看更多>>摘要：The Floquet technique provides a novel anomalous topological phase for non-equilibrium phase transitions.Based on the high symmetry of the quantum anomalous Hall model,the findings suggest a one-to-one correspondence between the average spin texture and the Floquet quasi-energy spectrum.A new approach is proposed to directly measure the quasi-energy spectrum,replacing previous measurements of the average spin texture.Finally,we proposed a reliable experimental scheme based on ion trap platforms.This scheme markedly reduces the measurement workload,improves the measurement fidelity,and is applicable to multiple platforms such as cold atoms and nuclear magnetic resonance.
查看更多>>摘要：We present a qubit-loss-free(QLF)fusion scheme for generating large-scale atom W states in cavity quantum elec-trodynamics(QED)system.Compared to the most current fusion schemes which are conditioned on the case where one particle can be extracted from each initial W state to the fusion process,our scheme will access one or two particles from each W state.Based on the atom-cavity-field detuned interaction,three|W>n+m+t states can be generated from the|W>n,|W>m,and|W>t states with the help of two auxiliary atoms,and three|W>n+m+t+q states can be generated from|W>n,|W>m,|W>t,and a|W>qstate with the help of three auxiliary atoms.Comparing the numerical simulations of the resource cost of fusing three small-size W states based on the previous schemes,our fusion scheme seems to be more efficient.This QLF fusion scheme can be generalized to the case of fusing k different or identical particle W states.Furthermore,with no qubit loss,it greatly reduces the number of fusion steps and prepares W states with larger particle numbers.
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