Accepted
, , Received Date: 2025-04-08
Abstract +
Hyperentanglement, as a high-dimensional quantum entanglement phenomenon with multiple degrees of freedom, plays a critical role in quantum communication, quantum computing, and high-dimensional quantum state manipulation. Unlike entangled states in a single degree of freedom, hyperentangled states establish entanglement relationships simultaneously in multiple degrees of freedom, such as polarization, path, and orbital angular momentum. Through entanglement-based distribution techniques, high-dimensional quantum information networks can be constructed. On this basis, a fully connected quantum network with hyperentanglement is constructed in this work, and the polarization and time-bin degree-of-freedom hyperentanglement is realized through the process of second-harmonic generation and spontaneous parametric down-conversion in periodically poled lithium niobate (PPLN) waveguide cascades. The hyperentangled state is then multiplexed into a single-mode fiber by using dense wavelength division multiplexing (DWDM) technology for transmission to terminal users. The quality of the entangled states in the two degrees of freedom is characterized using Franson-type interference and photon-pair coincidence measurement techniques. Polarization entangled states are subjected to quantum state tomography, and entanglement distribution technology is employed to achieve long-distance distribution and quantum key transmission within the network. Experimental results show that the two-photon interference visibility of both polarization and time-bin entanglement is greater than 95%, demonstrating the high quality of the hyperentanglement in the network. After 100-km-entanglement distribution, the fidelity of the quantum states in both degrees of freedom remains above 88%, indicating the effectiveness of long-distance entanglement distribution in this network. Additionally, it is verified that this network supports the distribution of quantum keys over a distance of more than 50 km between users. These results confirm the feasibility of a fully connected quantum network with hyperentanglement and demonstrate the potential for constructing large-scale metropolitan networks by using hyperentanglement. As a higher-dimensional entanglement, hyperentangled states can significantly enhance the capacity and efficiency of quantum information processing. Although the quantum communication is still in its early stages of development, achieving stable storage and transmission of entangled states in large-scale metropolitan networks remains a great challenge. By utilizing the frequency conversion properties and high integration characteristics of the periodically poled lithium niobate waveguides, the three-user hyperentangled quantum network constructed in this work provides a new solution for developing the large-scale metropolitan networks with high-dimensional quantum information networks., It is expected to provide a new platform for quantum tasks such as superdense coding and quantum teleportation
, , Received Date: 2025-04-15
Abstract +
Topological pumping based on Thouless pumping can be effectively applied to optical waveguide array systems to achieve robust light manipulation with strong disturbance resistance. One of its typical models, the Rice-Mele (R-M) model, enables directional light field to transmit from the leftmost (rightmost) waveguide to the rightmost (leftmost) waveguide, which can be utilized to realize fabrication-tolerant optical couplers. Adiabatic evolution is a critical factor influencing the transport of topological eigenstates. However, it requires the system’s parameter variation to be sufficiently slow, which leads to excessively long waveguide lengths, limiting device compactness. To reduce the size, non-adiabatic evolution offers a feasible alternative. Meanwhile, the adiabatic properties of topological pumping models introduce new degrees of freedom, expanding possibilities for light manipulation. Based on the R-M model, this work analyzes the relationship between adiabatic property and structure length L, investigates light field evolution behavior when adiabatic condition is violated, and explores the transition from adiabatic to non-adiabatic regimes. When adiabatic condition is satisfied (L1 = 1000 μm), the light field evolution aligns with the eigen edge state. The output mode is manifested as an edge state and localized at the edge waveguide. As length shortens (L2 = 250 μm and L4 = 30 μm), the deviation between light field and eigen edge state arises, and the eigen bulk states get involved in the light field. The output modes are manifested as the superposition of edge state and bulk state, with energy spreading to other waveguides. At a specific length (L3 = 110 μm), the light-field undergoes non-adiabatic evolution: initially deviating from the edge state and later returning to the edge state. This phenomenon is termed adiabatic equivalent evolution. The output mode is localized at the edge waveguide, which is the same as the adiabatic evolution. By analyzing the fidelity between output mode and eigen edge state, we demonstrate that the adiabaticity can effectively regulate fidelity, achieving signal on/off at the edge waveguide. As structural length decreases, fidelity gradually declines and exhibits an oscillating behavior. When fidelity approaches to 1, the adiabatic equivalent evolution emerges. The first-order perturbation approximation reveals that these oscillations stem from destructive interference between edge and bulk states, thereby confirming their intrinsic origin in band interference. This mechanism enables eigen edge state output at shorter lengths than adiabatic requirements, providing a reliable approach for miniaturizing devices. Furthermore, the fabrication tolerance is analyzed. Within the whole waveguides width deviation range of –35–+30 nm (relative deviation range of –7%–+6%), the transmission of edge waveguide through the adiabatic equivalent evolution is larger than 0.9. This work analyses light-field evolution process and underlying physics for topological pumping in non-adiabatic regimes, supplements theoretical methods for analyzing non-adiabatic evolution, and provides strategies for achieving eigen edge state output at reduced lengths. This work provides some feasible principles for designing topological optical waveguide arrays, guiding the development of compact and robust on-chip photonic devices such as optical couplers and splitters, which have broad application prospects in integrated photonics.
, , Received Date: 2025-03-14
Abstract +
In the face of the surge of air transport demand and the increasing risk of flight conflicts, it is very important to effectively manage flight conflicts and accurately identify key conflict aircraft. This paper presents a novel method for identifying critical nodes in flight conflict networks by integrating complex network theory with a weighted cycle ratio (WCR). By modeling aircraft as nodes and conflict relationships as edges, we construct a flight conflict network where the urgency of conflicts is reflected in edge weights. We extend the traditional cycle ratio (CR) concept to propose the WCR, which accounts for both the topological structure of the network and the urgency of conflicts. Furthermore, we combine the WCR with node strength (NS) to form an adjustable mixed indicator (MI) that adaptively balances the importance of nodes based on their involvement in cyclic conflict structure and their individual conflict strength. Through extensive simulations, including node deletion experiments and network robustness analyses, we demonstrate that our method can precisely pinpoint critical nodes in flight conflict networks. The results indicate that regulating these critical nodes can significantly reduce network complexity and conflict risks. Importantly, the effectiveness of our method increases with the complexity of the flight conflict network, making it particularly suitable for scenarios with high aircraft density and complex conflict patterns. Overall, this study not only deepens the theoretical understanding of complex aviation network analysis but also provides a practical tool for improving air traffic control efficiency and safety, thereby contributing to achieving more environmentally friendly and sustainable air transportation.
,
Abstract +
Our work constructs a non-Hermitian system with long range hopping under periodic driving. The Hamiltonian has chiral symmetry, which implies that the topological invariant can be defined. Based on the non-Bloch band theory and the Floquet method, relevant operators and topological number can be defined, providing quantitative approaches for studying topological properties. For example, by calculating the non-Bloch time-evolution factor, the Floquet operator, etc., it is found that the topological invariant is determined by the change of the phase of $U^{+}_{\epsilon=0,\pi}(\beta)$ as it moves along the generalized Brillouin zone, corresponding to the emergence of quasi-energy zero mode and $\pi$ mode.
Results show that the topological structure of the static system can be affected by periodic driving significantly. The topological phase boundary of the zero mode can be changed. When there is no periodic driving, there is no $\pi$ mode in the energy spectrum. After the introduction of periodic driving, a gap appears at the quasi-energy $\epsilon=\pi$, inducing a non-trivial $\pi$-mode phase and enriching the topological phase diagram. Further, the next nearest neighbor hopping has a unique effect in this system. It can induce large topological numbers. However, different from the static system, large topological numbers only appear in specific parameter intervals under periodic driving. As the strength of the next nearest neighbor hopping increases, the large topological number phase disappears instead, reflecting the non-monotonic regulation characteristics of the Floquet system. In addition, the introduction of the phase of the next nearest neighbor hopping can change the topological phase boundary, providing new ideas for experimentally regulating topological states.
This research is of significance in the field of topological phase transitions in non-Hermitian systems. Theoretically, it reveals the synergistic effect of long-range hopping and periodic driving, and improves the theoretical framework for the cross-research of long-range and dynamic regulation in non-Hermitian systems. From an application perspective, it provides theoretical support for experimentally realizing the controllable modulation of topological states, which is helpful to promote the development of fields such as low energy consumption electronic devices and topological quantum computing.
Results show that the topological structure of the static system can be affected by periodic driving significantly. The topological phase boundary of the zero mode can be changed. When there is no periodic driving, there is no $\pi$ mode in the energy spectrum. After the introduction of periodic driving, a gap appears at the quasi-energy $\epsilon=\pi$, inducing a non-trivial $\pi$-mode phase and enriching the topological phase diagram. Further, the next nearest neighbor hopping has a unique effect in this system. It can induce large topological numbers. However, different from the static system, large topological numbers only appear in specific parameter intervals under periodic driving. As the strength of the next nearest neighbor hopping increases, the large topological number phase disappears instead, reflecting the non-monotonic regulation characteristics of the Floquet system. In addition, the introduction of the phase of the next nearest neighbor hopping can change the topological phase boundary, providing new ideas for experimentally regulating topological states.
This research is of significance in the field of topological phase transitions in non-Hermitian systems. Theoretically, it reveals the synergistic effect of long-range hopping and periodic driving, and improves the theoretical framework for the cross-research of long-range and dynamic regulation in non-Hermitian systems. From an application perspective, it provides theoretical support for experimentally realizing the controllable modulation of topological states, which is helpful to promote the development of fields such as low energy consumption electronic devices and topological quantum computing.
,
Abstract +
Memristor-driven neuromorphic computing offers a promising path towards brain-inspired intelligence by emulating the multidimensional plasticity of biological synapses, thereby enabling energy-efficient parallel computation. Nevertheless, the attainment of robust environmental adaptability, particularly in response to fluctuating temperatures, continues to represent a substantial challenge for organic memristors in the context of dynamically modulating synaptic plasticity. In order to address this issue, a bio-inspired cobalt phthalocyanine (CoPc)-based memristor was developed, specifically designed for synergistic electric-thermal field modulation. The device employs the stable planar π-conjugated system of CoPc molecules and exploits dynamic oxygen vacancy (OV) migration at the CoPc/AlOx interface. A comprehensive electrical characterisation was conscucted, incorporating X-ray photoelectron spectroscopy (XPS), in-situ Raman spectroscopy, and temperature-dependent electrical measurements across a wide range (293–473 K). This was supported by physical modelling (SCLC, FNT, Arrhenius) to elucidate the underlying mechanisms. Evidence suggests that the apparatus is capable of effectively replicating essential synaptic plasiticy, encompassing short-term potentiation/depression (STP/STD), paired-pulse facilitation/depression (PPF/PPD), under the regulation of an electric field. The index rose to 151%, indicating a significant increase. Spike-amplitude-dependent plasticity (SADP, 45% weight increase), Spike-timing-dependent plasticity (STDP, ΔW = ± 90%), and learning-forgetting-relearning dynamics were revealed, unveiling cumulative memory effects linked to OV transport. It is crucial to note that the device demonstrates exceptional temperature resilience over the range of 293–473 K, characterised by a linear adaptive shift in its critical voltage (VCritical) from 8.7 V at 293 K to 4.5 V (dVCritical /dT = 0.023 V/K). Physical analysis attributes this adaptive threshold and stable operation to a dual-field synergistic mechanism based on trap-assisted carrier transport, elevated temperature thermally activates carriers, reducing the effective barrier for trap escape and OV migration activation energy (Ea = 0.073–0.312 eV), facilitating conduction via Fowler-Nordheim tunneling (FNT) at lower electric fields. Conversely, lower temperatures necessitate higher electric fields to enhance trap ionization efficiency via the Poole-Frenkel effect, compensating for reduced thermal energy. The exploitation of the linear VCritical-T relationship as a sensitive temperature transduction mechanism was validated through the construction of an intelligent fire warning system. This study incorporated a 6 × 6 CoPc memristor array integrated within household heaters, along with a deep learning model (20 × 16 + 16 × 8 + 8 × 1 fully connected network). The resultant model demonstrated a high abnormal temperature recognition accuracy of 96.54%. This work establishes a novel paradigm for environmentally adaptive neuromorphic devices through molecular/interface design and synergistic multi-field modulation, providing a physical realization of temperature-elastic synaptic operation and demonstrating its practical viability for robust next-generation brain-inspired computing platforms.
,
Abstract +
Objective The investigation of surface wave dispersion equations in viscoelastic non-Newtonian fluids constitutes the fundamental basis for thermophysical property characterization using surface light scattering techniques. Unlike Newtonian fluids, the complex viscosity of non-Newtonian systems exhibits nonlinear frequency- and stress relaxation time-dependent behavior. Consequently, the development of constitutive models capable of accurately capturing these complex viscosity characteristics is critical. Building upon the multi-relaxation-time Maxwell framework, this work establishes an explicit solution for the surface wave dispersion equation through modal decomposition of the total power spectrum, enabling systematic analysis of the influence of relaxation time parameters on surface wave mode distributions. The study quantitatively correlates the number of relaxation time parameters in the constitutive model with the nonlinear response capacity of the system. These findings provide a theoretical foundation for precise determination of surface wave characteristics in non-Newtonian fluids and advance the application of surface light scattering methodologies for thermophysical property measurement in viscoelastic fluid systems.
Methods Based on a multi-relaxation-time Maxwell model, the complex viscosity is formulated by incorporating multiple stress relaxation times. Utilizing non-depersonalization and polynomial decomposition, we derive the governing equations for surface wave dispersion and the associated power spectrum. By systematically varying the parameter n and dimensionless variables, the roots of the dispersion equations are analyzed to investigate surface wave modes—including capillary，elastic waves and overdamped modes—and their spectral signatures. A partial fraction expansion method is employed to decouple the total power spectrum into explicit modal contributions. This approach demonstrates how relaxation parameters dictate the distribution of surface wave modes, thereby elucidating the multimodal relaxation dynamics inherent to complex fluids.
The proposed framework extends the classical Maxwell model through the integration of multiple relaxation times, with a focus on surface wave dispersion behavior and spectral responses. Theoretically, it quantifies the influence of relaxation times on both the number and topological properties of roots within the complex plane. Furthermore, by correlating the dynamic behavior of these roots with physical constraints, the study establishes criteria for the existence of distinct surface wave modes and evaluates their relative contributions to the power spectrum.
Results and Discussions When the elastic modulus is low and approaches Newtonian fluid behavior, increasing the number of relaxation time parameters n, elevates the critical threshold for surface wave mode transitions. This simultaneously generates n purely imaginary roots corresponding to overdamped modes. At higher elastic modulus, the critical threshold vanishes, replaced by an oscillation-dominated regime requiring power spectrum analysis to resolve surface wave dynamics. Larger n values reduce the spatial extent of this oscillatory regime.
In systems with low elastic modulus, n primarily modulates peak amplitudes in the power spectrum rather than altering its overall shape. Near the oscillation regime, the power spectrum distinctly resolves contributions from capillary waves, elastic waves, and overdamped modes. Increasing n enhances elastic and overdamped mode intensities while suppressing capillary wave dominance. By incorporating additional relaxation times, the model gains enhanced resolution of multimodal relaxation dynamics, enabling precise characterization of viscoelasticity in complex non-Newtonian fluids.
Conclusions We improved the complex viscosity model by increasing the number of stress relaxation time parameters n. Through theoretical analysis of parameter variations under different conditions, the surface wave characteristics of non-Newtonian viscoelastic fluids were systematically investigated. The main conclusions are as follows: First, increasing the number of relaxation time parameters n augments the number of roots in the dispersion equation, introducing additional relaxation modes manifested as low-frequency overdamped behavior. Second, elevating stress relaxation time τ induces a critical oscillation regime, where surface wave dynamics require power spectrum analysis. Increasing n reduces the spatial extent of this regime or even enables its complete circumvention. Third, under identical parameters, higher n suppresses surface tension-driven capillary wave intensity while enhancing elastic wave dominance. Variations in n quantitatively reflect the viscoelastic heterogeneity of polymer networks. Fourth, selecting appropriate n values tailors the capacity of model to resolve specific relaxation modes, adapting it to diverse viscoelastic non-Newtonian fluids.
Methods Based on a multi-relaxation-time Maxwell model, the complex viscosity is formulated by incorporating multiple stress relaxation times. Utilizing non-depersonalization and polynomial decomposition, we derive the governing equations for surface wave dispersion and the associated power spectrum. By systematically varying the parameter n and dimensionless variables, the roots of the dispersion equations are analyzed to investigate surface wave modes—including capillary，elastic waves and overdamped modes—and their spectral signatures. A partial fraction expansion method is employed to decouple the total power spectrum into explicit modal contributions. This approach demonstrates how relaxation parameters dictate the distribution of surface wave modes, thereby elucidating the multimodal relaxation dynamics inherent to complex fluids.
The proposed framework extends the classical Maxwell model through the integration of multiple relaxation times, with a focus on surface wave dispersion behavior and spectral responses. Theoretically, it quantifies the influence of relaxation times on both the number and topological properties of roots within the complex plane. Furthermore, by correlating the dynamic behavior of these roots with physical constraints, the study establishes criteria for the existence of distinct surface wave modes and evaluates their relative contributions to the power spectrum.
Results and Discussions When the elastic modulus is low and approaches Newtonian fluid behavior, increasing the number of relaxation time parameters n, elevates the critical threshold for surface wave mode transitions. This simultaneously generates n purely imaginary roots corresponding to overdamped modes. At higher elastic modulus, the critical threshold vanishes, replaced by an oscillation-dominated regime requiring power spectrum analysis to resolve surface wave dynamics. Larger n values reduce the spatial extent of this oscillatory regime.
In systems with low elastic modulus, n primarily modulates peak amplitudes in the power spectrum rather than altering its overall shape. Near the oscillation regime, the power spectrum distinctly resolves contributions from capillary waves, elastic waves, and overdamped modes. Increasing n enhances elastic and overdamped mode intensities while suppressing capillary wave dominance. By incorporating additional relaxation times, the model gains enhanced resolution of multimodal relaxation dynamics, enabling precise characterization of viscoelasticity in complex non-Newtonian fluids.
Conclusions We improved the complex viscosity model by increasing the number of stress relaxation time parameters n. Through theoretical analysis of parameter variations under different conditions, the surface wave characteristics of non-Newtonian viscoelastic fluids were systematically investigated. The main conclusions are as follows: First, increasing the number of relaxation time parameters n augments the number of roots in the dispersion equation, introducing additional relaxation modes manifested as low-frequency overdamped behavior. Second, elevating stress relaxation time τ induces a critical oscillation regime, where surface wave dynamics require power spectrum analysis. Increasing n reduces the spatial extent of this regime or even enables its complete circumvention. Third, under identical parameters, higher n suppresses surface tension-driven capillary wave intensity while enhancing elastic wave dominance. Variations in n quantitatively reflect the viscoelastic heterogeneity of polymer networks. Fourth, selecting appropriate n values tailors the capacity of model to resolve specific relaxation modes, adapting it to diverse viscoelastic non-Newtonian fluids.
,
Abstract +
The spinor Bose-Einstein condensate (BEC) provides an ideal platform to observe and manipulate topological structures, which arise from the spin degrees of freedom and the superfluid nature of the gas. Artificial helicoidal spin-orbit coupling (SOC) in the spinor BEC, owing to the spatially varying gauge potential and the more flexible adjustability, provides possibly an unprecedented opportunity to search for novel quantum states. The previous studies of the BEC with helicoidal SOC are mainly focused on the two-component case. However, there are few reports on the studies of helicoidal SOC in three-component BEC. Especially considering one-dimensional three-component BEC, it remains an open question whether the helicoidal SOC can produce previously unknown types of topological excitations and phase diagrams. In this work, by solving quasi one-dimensional Gross-Pitaevskii equations, we study the ground state structure of one-dimensional helicoidal spin-orbit coupled three-component BEC. The numerical results show that, the helicoidal SOC can induce a phase separation among the components in ferromagnetic BEC. The phase diagram as a function of the helicoidal SOC strength and the gauge potential is obtained through systematic numerical calculations, which shows critical condition for occurring phase separation and for occurring phase miscibility in ferromagnetic BEC. Meanwhile, we also study the influences of the helicoidal SOC and the gauge potential on the antiferromagnetic BEC ground state. The numerical results show that the helicoidal SOC favors miscibility in antiferromagnetic BEC. When the helicoidal SOC strength or gauge potential increases, the ground state of antiferromagnetic BEC exhibits a stripe soliton structure. Adjusting the strength of helicoidal SOC or gauge potential can control the transitions between a plane-wave soliton and a stripe soliton. In addition, we show the changes of the particle number density maximum and the number of peaks of stripe solitons for tuning the helicoidal SOC strength or gauge potential. Our results show that helicoidal spin-orbit coupled BEC not only provide a controlled platform to investigate the exotic topological structures, but also are crucial for the transitions among different ground states. This work paves the way for future explorations of topological defect and the corresponding dynamical stability in quantum systems subjected to the helicoidal SOC.
,
Abstract +
Quantum secret sharing (QSS) is a cryptographic protocol that realizes secure distribution and reconstruction of secret information among multiple participants by leveraging fundamental principles of quantum mechanics. Most existing protocols rely on entangled states (such as Bell and GHZ states), but in practical applications, entangled state preparation is constrained by short quantum coherence time, low state fidelity, etc., making it difficult to implement entangled resource-dependent QSS protocols. This paper proposes a novel practical and verifiable multi-party QSS protocol based on orthogonal product states, which are easier to prepare than entangled states. In the protocol preparation stage, the secret distributor first converts pre-shared classical secret information into corresponding orthogonal product states according to encoding rules, and pre-shares a communication key with participants via quantum key distribution (QKD) to hide initial quantum sequence information through subsequent particle transformation operations. After preparing orthogonal product states, the distributor reorganizes particles by position—extracting particles at the same position from each state to form new sequences, scrambling their order—then applies Hadamard transformations with the pre-shared key, inserts decoy particles, and sends sequences to participants. Upon receipt, participants conduct eavesdropping detection, use the same key for inverse transformations, retain one particle from each sequence, and pass remaining particles sequentially until the last participant receives a complete set, triggering state verification with the distributor as arbiter. If verified, particles are returned to the first participant for a return stage with similar procedures. Only after both transmission and return stage verifications pass will the distributor reveal initial particle positions, allowing participants to collaboratively reconstruct the secret.In the protocol, the secret distributor acts as an arbitrator to verify with participants at periodic nodes (the end of the transmission stage and the end of the return stage) to determine whether the particle state information is error-free during transmission. If the verification fails at either stage, the protocol will be terminated immediately. Meanwhile, considering the possible change in the number of participants during the execution of the protocol, a dynamic scheme for personnel changes is designed to ensure the flexibility of the protocol. Through the analysis of possible internal and external attacks, it is proven that our protocol can safely resist the existing common attack methods. Using Qiskit simulation experiments, we have successfully modeled the core quantum procedures of the protocol. The experimental results provide significant computational validation for the theoretical feasibility of the protocol.
,
Abstract +
Active mass injection serves as an effective thermal protection technique by significantly reducing wall heat flux. However, it inherently alters boundary layer stability characteristics, leading to substantial impacts on the laminar-to-turbulent transition process. Crucially, the underlying mechanisms governing how different injected gases modulate flow stability remain unclear. To systematically analyze the effects of different gas injections on flow stability, this study investigates gas-specific mass injection effects by employing a multicomponent Navier-Stokes solver to compute flow fields with air, argon, and nitrogen injections. The influence of mass injection on flow stability was analyzed using linear stability theory, with subsequent differentiation of the distinct effects attributable to various injectant properties. The study demonstrates that mass injection displaces the freestream gas, forming an injection layer near the wall and consequently increasing the boundary layer thickness. Herein, the main boundary layer retains properties similar to the original boundary layer, while the injection layer exhibits significantly reduced temperature and velocity gradients, resulting in decreased wall heat flux and skin friction. Linear stability analysis reveals that while mass injection excites multiple higher-order instability modes, the second mode remains dominant. Notably, mass injection reduces the unstable region of the second mode and significantly decreases the integrated disturbance amplitude, thereby suppressing transition. This stabilizing effect is more pronounced with lighter gases. The differences in injected gas properties are mainly reflected in the viscosity coefficient, thermal conductivity, relative molecular weight, and diffusivity. Among these, the boundary layer thickness is primarily affected by the viscosity coefficient, relative molecular weight, and diffusivity of the injected gas, while the temperature within the boundary layer decreases with increasing thermal conductivity and specific heat capacity of the injected gas. The influence of injected gas properties on flow stability manifests through two distinct pathways: (1) modification of the base flow profile, and (2) alteration of mixed gas properties. Specifically, the transport coefficients (viscosity and diffusivity) of the injected gas primarily affect instability characteristics through Pathway 1, while the specific heat capacity mainly operates via Pathway 2. The relative molecular weight exerts combined effects through both pathways.
, , Received Date: 2025-03-28
Abstract +
, , Received Date: 2025-04-01
Abstract +
A novel target depth estimation method based on normal mode intensity match is proposed for shallow water environment by using horizontal array to overcome the performance degradation observed in traditional approaches under the condition that seabed parameters are not matched. Firstly, horizontal wavenumbers and normal mode intensities are estimated through wavenumber domain beamforming. Secondly, modal function of normal mode inversion is performed by solving the modal function characteristic equation by using the finite difference method. Thirdly, the match degree between inverted and estimated normal mode intensities is evaluated to estimate target depth. The numerical simulation results show that the proposed method can accurately estimate the target depth in shallow water scenarios without knowing the seabed parameters. Furthermore, the performance of the method is analyzed under different conditions including different seabed parameters, array apertures and source frequencies. The results reveal three conclusions: 1) the mismatch of seabed parameters has no influence on the method; 2) the effective performance of full depth source estimation requires no less than 128 array elements, $50 - 150{\text{ Hz}}$ a frequency band range of 50－150 Hz, and the signal-to-noise radio of the element on a horizontal line array exceeding –10 dB $ - 10{\text{ dB}}$; 3) the method has robust performance against sound speed profile mismatch. Finally, the feasibility of the proposed method is validated by the experimental data received by a horizontally towing 77-element array during the shallow-water sea trial in the South China Sea.
, , Received Date: 2025-03-07
Abstract +
This study tackles the significant challenge of phase separation in mixed halide (Br–/Cl–) perovskite systems, which severely affects the spectral stability of blue perovskite light-emitting diodes (PeLEDs). A compositional engineering strategy is proposed, precisely controlling the Cs:Pb molar ratio (1∶1 to 1.1∶1) in precursor solutions to construct a CsPb(Br1–xClx)3/Cs4Pb(Br1–xClx)6 composite phase structure. Transmission electron microscopy (TEM) mapping and X-ray diffraction (XRD) analysis confirm that Cs4Pb(Br1–xClx)6 nanocrystals (5–8 nm in diameter) grow in situ and uniformly encapsulate CsPb(Br1–xClx)3 microparticles (50–100 nm). This composite architecture has double functional advantages: 1) the Cs4PbX6 shell acts as a physical barrier, reducing halide ion migration activation energy and suppressing phase segregation during continuous operation; 2) the wide-bandgap (3.9–4.3 eV) Cs4PbX6 induces quantum confinement effects, confining carriers within CsPbX3 while passivating defect states, thereby improving perovskite performance. The optimized PeLED achieves notable improvements in brightness, external quantum efficiency, and operational stability, maintaining stable emission at 478 nm under a 50 mA/cm² current density. This is achieved by inhibiting halide phase separation and enhancing the efficiency of carrier recombination achieved by the cesium-lead halide heterojunction system. This work provides fundamental insights into phase-stable perovskite design via composite crystallization kinetics, providing a viable pathway toward commercial-grade blue PeLEDs for full-color displays.
, , Received Date: 2025-03-08
Abstract +
With the discovery of two-dimensional materials like graphene, the relativistic two-dimensional Dirac equation has received increasing attention from researchers. Accurately solving the Dirac equation in electromagnetic fields is the foundation for studying and manipulating quantum states of Dirac electrons. Sectioned series expansion method is successful and accurate in solving SchrÖdinger equation under complex electromagnetic fields. Dirac equation is a system of coupled first-order differential equations with undermined eigenvalues, and it is more difficult to solve. By applying the sectioned series expansion principle to Dirac equation and conducting series expansions in regular, Taylor and irregular regions, we obtain an accurate method with wide applicability. With the method, a universal criterion for bound states of Dirac electrons in electromagnetic fields is derived and the energy levels and wave functions of bound states can be accurately calculated.The criterion provided by Eq. (52) given in the main text body shows that the magnetic field and mass field help to confine Dirac electrons while the electric field tends to deconfine them due to Klein tunneling. When the highest power of the electric potential is equal to that of the magnetic vector potential or the mass field, confined-deconfiend states depend on the comparison of their coefficients. We apply the method to two cases: one is massive Dirac electron in Coulomb electric potential (relativistic two-dimensional hydrogen-like atom) and the other is Dirac electron in uniform mangetic field (mangetic vector potenial is A = 1/2Br) and linear electric potential V = Fr. The energy levels of the hydrogen-like atom are calculated and compared with analytical solutions, demonstrating the exceptional accuracy of the method. By solving Dirac equation under uniform magnetic field and linear electric potential, the method proves to be broadly applicable to the solutions of Dirac equation under complex electromagnetic fields. Under uniform magnetic field B and V = Fr, as the F increases, level orders of negative energy states change and at the critical point F = 0.5B, the bound states of positive ones still exist while only certain negative ones can exist on condition that their energies exceed zero. The sectioned series expansion method provides an effective computational framework for Dirac equation and it deepens our understanding of relativistic quantum mechanics.
, , Received Date: 2025-03-21
Abstract +
In high-energy density physics (HEDP) experiments, accurate diagnostics of physical parameters such as electron temperature, plasma density, and ionization state are essential for understanding matter behavior under extreme conditions. In these cases, X-ray spectroscopic technique, especially those using crystal spectrometers, is widely used to achieve high spectral resolution. However, a common challenge in such experiments lies in the inherent low brightness and poor spatial coherence of laboratory-based X-ray sources, which limit photon throughput, thus the diagnostic accuracy. Therefore, improving the X-ray optical transmission efficiency between the source and the detector is a key step to improve the performance of the whole system. Capillary X-ray optics, which function based on the principle of total internal reflection within hollow glass structures, provides a promising avenue for beam shaping, collimation, and focusing in the soft-to-hard X-ray range. These optical devices are usually divided into polycapillary type and monocapillary type. While polycapillary optics are composed of numerous micro-channels and used primarily for collimating or focusing divergent X-rays, monocapillary lenses—consisting of single curved channels—provide more precise beam control and are particularly suitable for customized X-ray pathways. Depending on the curvature of the inner reflective surface, monocapillaries are classified into conical, parabolic, and ellipsoidal geometries. In this study, we propose and analyze a novel design of a large-caliber conical glass tube, specifically tailored to address the issue of low light utilization in multi-channel focusing spectrographs with spatial resolution (FSSR). The proposed conical glass tube is made of a single large-diameter capillary structure, simplifying alignment requirements and reducing the surface manufacturing precision typically required by complex aspheric lenses. Its geometric configuration enables X-rays from extended or weak sources to be redirected and controlled to convergef, thereby improving photon collection without significantly altering beam divergence. To quantify the performance of this optical system, we develop a detailed mathematical ray-tracing model and implement it in MATLAB. The model combines physical parameters such as capillary inner diameter, taper angle, reflection loss, and source-detector geometry. Numerical simulations show that compared with traditional flat or slit based systems, the new conical design improves source utilization efficiency by 3.1 times. Furthermore, the lens exhibits a ring-shaped enhancement region in the output intensity profile, which can be regulated by adjusting the capillary geometry and source positioning. This feature enables the spatial customization of the beam profile, thereby facilitating optimized coupling with downstream spectroscopic components or imaging systems. In conclusion, the proposed large-aperture conical monocapillary X-ray lens provides a practical and efficient solution for enhancing X-ray optical transport in low-brightness source environments. Its simple construction, tunable focusing characteristics, and compatibility with diverse X-ray source types make it a compelling candidate for integration into a high-resolution X-ray diagnostic system, particularly in HEDP and laboratory-scale X-ray spectroscopy. This work not only introduces a novel optical approach but also provides a robust theoretical and simulation framework for guiding future experimental design and application of capillary-based X-ray optics.
, , Received Date: 2025-03-24
Abstract +
Microscopic and macroscopic magnetic responses are widely used for non-destructive testing and evaluating stress. The basic principle is that the magnetic domain pattern and magnetic domain dynamics are highly dependent on applied tensile stress. Understanding the evolution of magnetic domains under the action of multi-field coupling is critical for developing novel magnetic non-destructive testing technology. In this work, the influences of stress on magnetic domain and magneto-acoustic emission signals in polycrystalline materials are investigated based on the magneto-optical Kerr imaging and magneto-acoustic emission detection system. On a macroscopic scale, the mapping relationship between the magneto-acoustic emission signal and stress is established. Microscopically, the influences of the stress and grain boundaries on the magnetic domain patterns are investigated. And a mapping relationship between percentage of supplementary domains and stress is built. Finally, the interrelation between the domain wall dynamics and the magneto-acoustic emission signal is revealed from the nucleation of supplementary domains and their stress-dependent evolution. The results indicate that the magnetoelastic effect reduces the density of supplementary domains and 90° domains, which weakens the magneto-acoustic emission signal. The stress-magneto-acoustic model and the influence of the stress on the magnetic domain in this work reveal the mechanism of magneto-acoustic emission technique for stress measurement. It also provides a theoretical foundation for developing stress-magnetic-acoustic models and magnetic non-destructive testing technology.
- 1
- 2
- 3
- 4
- 5
- ...
- 15
- 16
