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    2025年, 第34卷, 第1期 刊出日期:2025-01-25 上一期   
    Darboux transformation, positon solution, and breather solution of the third-order flow Gerdjikov-Ivanov equation
    Shuzhi Liu(刘树芝), Ning-Yi Li(李宁逸), Xiaona Dong(董晓娜), and Maohua Li(李茂华)
    2025 (1):  10201-010201.  doi: 10.1088/1674-1056/ad8ec6
    摘要 ( 38 )   PDF(1878KB) ( 24 )  
    The third-order flow Gerdjikov-Ivanov (TOFGI) equation is studied, and the Darboux transformation (DT) is used to obtain the determinant expression of the solution of this equation. On this basis, the soliton solution, rational solution, positon solution, and breather solution of the TOFGI equation are obtained by taking zero seed solution and non-zero seed solution. The exact solutions and dynamic properties of the Gerdjikov-Ivanov (GI) equation and the TOFGI equation are compared in detail under the same conditions, and it is found that there are some differences in the velocities and trajectories of the solutions of the two equations.
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    Self-similarity of multilayer networks
    Bing Wang(王冰), Huizhi Yu(于蕙芷), and Daijun Wei(魏代俊)
    2025 (1):  10202-010202.  doi: 10.1088/1674-1056/ad8a47
    摘要 ( 0 )   PDF(1616KB) ( 0 )  
    Research on the self-similarity of multilayer networks is scarce, when compared to the extensive research conducted on the dynamics of these networks. In this paper, we use entropy to determine the edge weights in each sub-network, and apply the degree-degree distance to unify the weight values of connecting edges between different sub-networks, and unify the edges with different meanings in the multilayer network numerically. At this time, the multilayer network is compressed into a single-layer network, also known as the aggregated network. Furthermore, the self-similarity of the multilayer network is represented by analyzing the self-similarity of the aggregate network. The study of self-similarity was conducted on two classical fractal networks and a real-world multilayer network. The results show that multilayer networks exhibit more pronounced self-similarity, and the intensity of self-similarity in multilayer networks can vary with the connection mode of sub-networks.
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    Multiparameter generalized universal characters and multiparameter generalized B-type universal characters
    Jingfan Wang(王竸凡), and Zhaowen Yan(颜昭雯)
    2025 (1):  10203-010203.  doi: 10.1088/1674-1056/ad925b
    摘要 ( 15 )  
    We construct the quantum fields presentation of the generalized universal character and the generalized B-type universal character, and by acting the quantum fields presentations to the constant $1$, the generating functions are derived. Furthermore, we introduce two integrable systems known as the generalized UC (GUC) hierarchy and the generalized B-type UC (GBUC) hierarchy satisfied by the generalized universal character and the generalized B-type universal character, respectively. Based on infinite sequences of complex numbers, we further establish the multiparameter generalized universal character and the multiparameter generalized B-type universal character, which have been proved to be solutions of the GUC hierarchy and the GBUC hierarchy, respectively.
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    Side-channel free quantum digital signature with source monitoring
    Luo-Jia Ma(马洛嘉), Ming-Shuo Sun(孙铭烁), Chun-Hui Zhang(张春辉), Hua-Jian Ding(丁华建), Xing-Yu Zhou(周星宇), Jian Li(李剑), and Qin Wang(王琴)
    2025 (1):  10301-010301.  doi: 10.1088/1674-1056/ad8871
    摘要 ( 34 )   PDF(350KB) ( 19 )  
    Quantum digital signature (QDS) can guarantee the information-theoretical security of a signature with the fundamental laws of quantum physics. However, most current QDS protocols do not take source security into account, leading to an overestimation of the signature rate. In this paper, we propose to utilize Hong-Ou-Mandel interference to characterize the upper bound of the source imperfections, and further to quantify information leakage from potential side-channels. Additionally, we combine decoy-state methods and finite-size analysis in analyzing the signature rate. Simulation results demonstrate the performance and feasibility of our approach. Our current work can improve the practical security of QDS systems, thereby promoting their further networked applications.
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    Multi-hop quantum teleportation based on HSES via GHZ-like states
    She-Xiang Jiang(蒋社想), Xiao-Long Wei(韦晓龙), Jin-Huan Li(李金欢), and Shuai-Shuai Li(李帅帅)
    2025 (1):  10302-010302.  doi: 10.1088/1674-1056/ad8db0
    摘要 ( 33 )   PDF(748KB) ( 11 )  
    Implementing quantum wireless multi-hop network communication is essential to improve the global quantum network system. In this paper, we employ eight-level GHZ states as quantum channels to realize multi-hop quantum communication, and utilize the logical relationship between the measurements of each node to derive the unitary operation performed by the end node. The hierarchical simultaneous entanglement switching (HSES) method is adopted, resulting in a significant reduction in the consumption of classical information compared to multi-hop quantum teleportation (QT) based on general simultaneous entanglement switching (SES). In addition, the proposed protocol is simulated on the IBM Quantum Experiment platform (IBM QE). Then, the data obtained from the experiment are analyzed using quantum state tomography, which verifies the protocol's good fidelity and accuracy. Finally, by calculating fidelity, we analyze the impact of four different types of noise (phase-damping, amplitude-damping, phase-flip and bit-flip) in this protocol.
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    Established conversions for hybrid entangled states assisted by error-predicted parity-discriminated devices
    Fang-Fang Du(杜芳芳), Zhi-Guo Fan(范志国), Xue-Mei Ren(任雪梅), Ming Ma(马明), and Wen-Yao Liu(刘文耀)
    2025 (1):  10303-010303.  doi: 10.1088/1674-1056/ad8fa0
    摘要 ( 28 )   PDF(485KB) ( 12 )  
    Hybrid entangled states are crucial in quantum physics, offering significant benefits for hybrid quantum communication and quantum computation, and then the conversion of hybrid entangled states is equally critical. This paper presents two novel schemes, that is, one converts the two-qubit hybrid Knill-Laflamme-Milburn (KLM) entangled state into Bell states and the other one transforms the three-qubit hybrid KLM state into Greenberger-Horne-Zeilinger (GHZ) states assisted by error-predicted and parity-discriminated devices. Importantly, the integration of single photon detectors into the parity-discriminated device enhances predictive capabilities, mitigates potential failures, and facilitates seamless interaction between the nitrogen-vacancy center and photons, so the two protocols operate in an error-predicted way, improving the experimental feasibility. Additionally, our schemes demonstrate robust fidelities (close to 1) and efficiencies, indicating their feasibility with existing technology.
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    Precision bounds for quantum phase estimation using two-mode squeezed Gaussian states
    Jian-Dong Zhang(张建东), Chuang Li(李闯), Lili Hou(侯丽丽), and Shuai Wang(王帅)
    2025 (1):  10304-010304.  doi: 10.1088/1674-1056/ad8dc0
    摘要 ( 11 )  
    Quantum phase estimation based on Gaussian states plays a crucial role in many application fields. In this paper, we study the precision bound for the scheme using two-mode squeezed Gaussian states. The quantum Fisher information is calculated and its maximization is used to determine the optimal parameters. We find that two single-mode squeezed vacuum states are the optimal Gaussian inputs for a fixed two-mode squeezing process. The corresponding precision bound is sub-Heisenberg-limited and scales as $N^{-1}$/2. For practical purposes, we consider the effects originating from photon loss. The precision bound can still outperform the shot-noise limit when the lossy rate is below 0.4. Our work may demonstrate a significant and promising step towards practical quantum metrology.
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    Quantum color image encryption: Dual scrambling scheme based on DNA codec and quantum Arnold transform
    Tao Cheng(程涛), Run-Sheng Zhao(赵润盛), Shuang Wang(王爽), Kehan Wang(王柯涵), and Hong-Yang Ma(马鸿洋)
    2025 (1):  10305-010305.  doi: 10.1088/1674-1056/ad8a4b
    摘要 ( 19 )   PDF(6968KB) ( 22 )  
    In the field of Internet, an image is of great significance to information transmission. Meanwhile, how to ensure and improve its security has become the focus of international research. We combine DNA codec with quantum Arnold transform (QArT) to propose a new double encryption algorithm for quantum color images to improve the security and robustness of image encryption. First, we utilize the biological characteristics of DNA codecs to perform encoding and decoding operations on pixel color information in quantum color images, and achieve pixel-level diffusion. Second, we use QArT to scramble the position information of quantum images and use the operated image as the key matrix for quantum XOR operations. All quantum operations in this paper are reversible, so the decryption operation of the ciphertext image can be realized by the reverse operation of the encryption process. We conduct simulation experiments on encryption and decryption using three color images of "Monkey", "Flower", and "House". The experimental results show that the peak value and correlation of the encrypted images on the histogram have good similarity, and the average normalized pixel change rate (NPCR) of RGB three-channel is 99.61%, the average uniform average change intensity (UACI) is 33.41%, and the average information entropy is about 7.9992. In addition, the robustness of the proposed algorithm is verified by the simulation of noise interference in the actual scenario.
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    Topological states constructed by two different trivial quantum wires
    Jing-Run Lin(林景润), Linxi Lv(吕林喜), and Zheng-Wei Zuo(左正伟)
    2025 (1):  10306-010306.  doi: 10.1088/1674-1056/ad8fa3
    摘要 ( 14 )  
    The topological states of the two-leg and three-leg ladders formed by two trivial quantum wires with different lattice constants are theoretically investigated. Firstly, we take two trivial quantum wires with a lattice constant ratio of 1:2 as an example. For the symmetric nearest-neighbor intra-chain hopping two-leg ladder, the inversion symmetry protected topological insulator phase with two degenerate topological edge states appears. When the inversion symmetry is broken, the topological insulators with one or two topological edge states of different energies and topological metals with edge states embedded in the bulk states could emerge depending on the filling factor. The topological origin of these topological states in the two-leg ladders is the topological properties of the Chern insulators and Chern metals. According to the arrangement of two trivial quantum wires, we construct two types of three-leg ladders. Each type of the three-leg ladder could be divided into one trivial subspace and one topological nontrivial subspace by unitary transformation. The topological nontrivial subspace corresponds to the effective two-leg ladder model. As the filling factor changes, the system could be in topological insulators or topological metals phases. When the two-leg ladder is constructed by two trivial quantum wires with a lattice constant ratio of 1:3 and 2:3, the system could also realize rich topological states such as the topological insulators and topological metals with the topological edge states. These rich topological states in the two-leg and three-leg ladders could be confirmed by current experimental techniques.
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    Phase-matching enhanced quantum phase and amplitude estimation of a two-level system in a squeezed reservoir
    Yan-Ling Li(李艳玲), Cai-Hong Liao(廖彩红), and Xing Xiao(肖兴)
    2025 (1):  10307-010307.  doi: 10.1088/1674-1056/ad8f9e
    摘要 ( 21 )   PDF(10390KB) ( 10 )  
    Squeezed reservoir engineering is a powerful technique in quantum information that combines the features of squeezing and reservoir engineering to create and stabilize non-classical quantum states. In this paper, we focus on the previously neglected aspect of the impact of the squeezing phase on the precision of quantum phase and amplitude estimation based on a simple model of a two-level system (TLS) interacting with a squeezed reservoir. We derive the optimal squeezed phase-matching conditions for phase $\phi$ and amplitude $\theta$ parameters, which are crucial for enhancing the precision of quantum parameter estimation. The robustness of the squeezing-enhanced quantum Fisher information against departures from these conditions is examined, demonstrating that minor deviations from phase-matching can still result in remarkable precision of estimation. Additionally, we provide a geometric interpretation of the squeezed phase-matching conditions from the classical motion of a TLS on the Bloch sphere. Our research contributes to a deeper understanding of the operational requirements for employing squeezed reservoir engineering to advance quantum parameter estimation.
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    Correcting on-chip distortion of control pulses with silicon spin qubits
    Ming Ni(倪铭), Rong-Long Ma(马荣龙), Zhen-Zhen Kong(孔真真), Ning Chu(楚凝), Wei-Zhu Liao(廖伟筑), Sheng-Kai Zhu(祝圣凯), Chu Wang(王儲), Gang Luo(罗刚), Di Liu(刘頔), Gang Cao(曹刚), Gui-Lei Wang(王桂磊), Hai-Ou Li(李海欧), and Guo-Ping Guo(郭国平)
    2025 (1):  10308-010308.  doi: 10.1088/1674-1056/ad8db1
    摘要 ( 15 )  
    In semiconductor quantum dot systems, pulse distortion is a significant source of coherent errors, which impedes qubit characterization and control. Here, we demonstrate two calibration methods using a two-qubit system as the detector to correct distortion and calibrate the transfer function of the control line. Both methods are straightforward to implement, robust against noise, and applicable to a wide range of qubit types. The two methods differ in correction accuracy and complexity. The first, coarse predistortion (CPD) method, partially mitigates distortion. The second, all predistortion (APD) method, measures the transfer function and significantly enhances exchange oscillation uniformity. Both methods use exchange oscillation homogeneity as the metric and are suitable for any qubit driven by a diabatic pulse. We believe these methods will enhance qubit characterization accuracy and operation quality in future applications.
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    Improving cutoff frequency estimation via optimized π-pulse sequence
    Wang-Sheng Zheng(郑王升), Chen-Xia Zhang(张晨霞), and Bei-Li Gong(龚贝利)
    2025 (1):  10309-010309.  doi: 10.1088/1674-1056/ad9ba1
    摘要 ( 14 )  
    The cutoff frequency is one of the crucial parameters that characterize the environment. In this paper, we estimate the cutoff frequency of the Ohmic spectral density by applying the $\pi$-pulse sequences (both equidistant and optimized) to a quantum probe coupled to a bosonic environment. To demonstrate the precision of cutoff frequency estimation, we theoretically derive the quantum Fisher information (QFI) and quantum signal-to-noise ratio (QSNR) across sub-Ohmic, Ohmic, and super-Ohmic environments, and investigate their behaviors through numerical examples. The results indicate that, compared to the equidistant $\pi$-pulse sequence, the optimized $\pi$-pulse sequence significantly shortens the time to reach maximum QFI while enhancing the precision of cutoff frequency estimation, particularly in deep sub-Ohmic and deep super-Ohmic environments.
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    Multi-protocol relay chaining for large-scale quantum key distribution networks
    Yuan Cao(曹原), Xiaosong Yu(郁小松), Yongli Zhao(赵永利), Chunhui Zhang(张春辉), Xingyu Zhou(周星宇), Jie Zhang(张杰), and Qin Wang(王琴)
    2025 (1):  10310-010310.  doi: 10.1088/1674-1056/ad9018
    摘要 ( 5 )   PDF(662KB) ( 1 )  
    As the first stage of the quantum Internet, quantum key distribution (QKD) networks hold the promise of providing long-term security for diverse users. Most existing QKD networks have been constructed based on independent QKD protocols, and they commonly rely on the deployment of single-protocol trusted relay chains for long reach. Driven by the evolution of QKD protocols, large-scale QKD networking is expected to migrate from a single-protocol to a multi-protocol paradigm, during which some useful evolutionary elements for the later stages of the quantum Internet may be incorporated. In this work, we delve into a pivotal technique for large-scale QKD networking, namely, multi-protocol relay chaining. A multi-protocol relay chain is established by connecting a set of trusted/untrusted relays relying on multiple QKD protocols between a pair of QKD nodes. The structures of diverse multi-protocol relay chains are described, based on which the associated model is formulated and the policies are defined for the deployment of multi-protocol relay chains. Furthermore, we propose three multi-protocol relay chaining heuristics. Numerical simulations indicate that the designed heuristics can effectively reduce the number of trusted relays deployed and enhance the average security level versus the commonly used single-protocol trusted relay chaining methods on backbone network topologies.
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    Optimization strategies for operational parameters of Rydberg atom-based amplitude modulation receiver
    Yuhao Wu(吴宇豪), Dongping Xiao(肖冬萍), Huaiqing Zhang(张淮清), and Sheng Yan(阎晟)
    2025 (1):  13201-013201.  doi: 10.1088/1674-1056/ad886a
    摘要 ( 19 )   PDF(1864KB) ( 34 )  
    The Rydberg atom-based receiver, as a novel type of antenna, demonstrates broad application prospects in the field of microwave communications. However, since Rydberg atomic receivers are nonlinear systems, mismatches between the parameters of the received amplitude modulation (AM) signals and the system's linear workspace and demodulation operating points can cause severe distortion in the demodulated signals. To address this, the article proposes a method for determining the operational parameters based on the mean square error (MSE) and total harmonic distortion (THD) assessments and presents strategies for optimizing the system's operational parameters focusing on linear response characteristics (LRC) and linear dynamic range (LDR). Specifically, we employ a method that minimizes the MSE to define the system's linear workspace, thereby ensuring the system has a good LRC while maximizing the LDR. To ensure that the signal always operates within the linear workspace, an appropriate carrier amplitude is set as the demodulation operating point. By calculating the THD at different operating points, the LRC performance within different regions of the linear workspace is evaluated, and corresponding optimization strategies based on the range of signal strengths are proposed. Moreover, to more accurately restore the baseband signal, we establish a mapping relationship between the carrier Rabi frequency and the transmitted power of the probe light, and optimize the slope of the linear demodulation function to reduce the MSE to less than $0.8\times 10^{-4}$. Finally, based on these methods for determining the operational parameters, we explore the effects of different laser Rabi frequencies on the system performance, and provide optimization recommendations. This research provides robust support for the design of high-performance Rydberg atom-based AM receivers.
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    Effect of orbital symmetry on atomic ionization in near-infrared laser fields
    Manqi Xu(徐嫚琦), Shilin Hu(胡师林), Li Guo(郭丽), and Jing Chen(陈京)
    2025 (1):  13202-013202.  doi: 10.1088/1674-1056/ad8dbe
    摘要 ( 12 )  
    We have performed a comparative study of the photoelectron spectra adopting different initial states (2s or 2p$_0$) of hydrogen atoms in a near-infrared laser pulse by using the full three-dimensional time-dependent Schrödinger equation. It is demonstrated that the atomic photoelectron spectra oscillate out of step as a function of electron kinetic energies for different initial states (2s or 2p$_0$), which is well reproduced by the simulations based on strong field approximation, and the above distinct feature is ascribed to the different interferences from the partial electron wave packets detached by positive and negative electric fields for different initial states of 2s and 2p$_0$.
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    Blood-based magnetohydrodynamic Casson hybrid nanofluid flow on convectively heated bi-directional porous stretching sheet with variable porosity and slip constraints
    Showkat Ahmad Lone, Rawan Bossly, Fuad S. Alduais, Afrah Al-Bossly, Arshad Khan, Anwar Saeed
    2025 (1):  14101-014101.  doi: 10.1088/1674-1056/ad8a45
    摘要 ( 4 )   PDF(3609KB) ( 0 )  
    Fluid flow through porous spaces with variable porosity has wide-range applications, notably in biomedical and thermal engineering, where it plays a vital role in comprehending blood flow dynamics within cardiovascular systems, heat transfer and thermal management systems improve efficiency using porous materials with variable porosity. Keeping these important applications in view, in current study blood-based hybrid nanofluid flow has considered on a convectively heated sheet. The sheet exhibits the properties of a porous medium with variable porosity and extends in both the $x$ and $y$ directions. Blood has used as base fluid in which the nanoparticles of Cu and CuO have been mixed. Thermal radiation, space-dependent, and thermal-dependent heat sources have been incorporated into the energy equation, while magnetic effects have been integrated into the momentum equations. Dimensionless variables have employed to transform the modeled equations into dimensionless form and facilitating their solution using bvp4c approach. It has concluded in this study that, both the primary and secondary velocities augmented with upsurge in variable porous factor and declined with escalation in stretching ratio, Casson, magnetic, and slip factors along $x$- and $y$-axes. Thermal distribution has grown up with upsurge in Casson factor, magnetic factor, thermal Biot number, and thermal/space-dependent heat sources while has retarded with growth in variable porous and stretching ratio factors. The findings of this investigation have been compared with the existing literature, revealing a strong agreement among present and established results that ensured the validation of the model and method used in this work.
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    Influence of quasi-electrostatic support on amplification of space charge waves in amplification section of a superheterodyne free electron laser
    A. V. Lysenko and S. S. Ilin
    2025 (1):  14102-014102.  doi: 10.1088/1674-1056/ad8869
    摘要 ( 1 )   PDF(1424KB) ( 0 )  
    A theoretical study of the influence of a quasi-electrostatic support on the amplification level of the slow space charge wave (SCW) in the amplification section of a superheterodyne free electron laser (FEL) was carried out. One of the ways to significantly increase the saturation level of the slow SCW is maintaining the conditions of a three-wave parametric resonance between the slow, fast SCWs and the resulting pump electric field. This can be done by introducing the quasi-electrostatic support in the superheterodyne FEL amplification section. Also, it was found that the generated pump electric field significantly influences the maintenance of parametric resonance conditions. As a result, this increases the saturation level of the slow SCW by 70%. Finally, the quasi-electrostatic support significantly reduces the maximum value of the electrostatic undulator pump field strength, which is necessary to achieve the maximum saturation level of the slow SCW.
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    Enhanced mechanical squeezing in an optomechanical system via backward stimulated Brillouin scattering
    Shan-Shan Chen(陈珊珊), Yi-Long Xie(谢亦龙), Jing-Jing Zhang(张京京), Na-Na Zhang(张娜娜), Yong-Rui Guo(郭永瑞), Huan Yang(杨桓), and Yong Ma(马勇)
    2025 (1):  14201-014201.  doi: 10.1088/1674-1056/ad8cc0
    摘要 ( 35 )   PDF(1572KB) ( 12 )  
    We investigate theoretically the enhancement of mechanical squeezing in a multimode optomechanical system by introducing a coherent phonon-photon interaction via the backward stimulated Brillouin scattering (BSBS) process. The coherent photon-phonon interaction where two optical modes couple to a Brillouin acoustic mode with a large decay rate provides an extra channel for the cooling of a Duffing mechanical oscillator. The squeezing degree and the robustness to the thermal noises of the Duffing mechanical mode can be enhanced greatly. When the Duffing nonlinearity is weak, the squeezing degree of the mechanical mode in the presence of BSBS can be improved by more than one order of magnitude compared with that in the absence of BSBS. Our scheme may be extended to other quantum systems to study novel quantum effects.
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    Giant enhancement of negative friction by resonant coupling between localized surface phonon polaritons and graphene plasmonics
    Kaipeng Liu(柳开鹏), Shuai Zhou(周帅), Shiwei Dai(戴士为), and Lixin Ge(葛力新)
    2025 (1):  14202-014202.  doi: 10.1088/1674-1056/ad886c
    摘要 ( 16 )  
    Negative friction refers to a frictional force that acts in the same direction as the motion of an object, which has been predicted in terahertz (THz) gain systems [{\em Phys. Rev. B} {\bf 108} 045406 (2023)]. In this work, we investigate the enhancement of the negative friction experienced by nanospheres placed near a graphene substrate. We find that the magnitude of negative friction is related to the resonant coupling between the surface plasmon polaritons (SPPs) of the graphene and localized surface phonon polaritons (LSPhP) of nanospheres. We exam nanospheres consisted of several different materials, including SiO$_{2}$, SiC, ZnSe, NaCl, lnSb. Our results suggest that the LSPhP of NaCl nanospheres match effectively with the amplified SPPs of graphene sheets. The negative friction for NaCl nanospheres can be enhanced about one-to-two orders of magnitude compared to that of silica (SiO$_{2}$) nanospheres. At the resonant peak of negative friction, the required quasi-Fermi energy of graphene is lower for NaCl nanospheres. Our finds hold great prospects for the mechanical manipulations of nanoscale particles.
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    In-phase collective unconventional photon blockade and its stability in an asymmetrical cavity containing N bosonic atoms
    Ying Luo(罗颖), Xinqin Zhang(张新琴), Yi Xiao(肖祎), Jingping Xu(许静平), Haozhen Li(李浩珍), Yaping Yang(羊亚平), and Xiuwen Xia(夏秀文)
    2025 (1):  14203-014203.  doi: 10.1088/1674-1056/ad8cbf
    摘要 ( 24 )   PDF(437KB) ( 13 )  
    We present work on a cavity-driven QED system combining an asymmetrical Fabry-Perot cavity and $N$ two-level atoms (TLAs) and show the convenience of simplifying from distinguishable atoms to undistinguishable bosons when the atoms are prepared in the same initial state. Such simplification is valid even when the atoms are not prepared in the in-phase condition, since any partial in-phase initial state will evolve into the ground state through a relaxation process. Thus, we get a reduced group of differential equations by introducing the Dicke states, and the under-zero Lyapunov exponents verify its stability. We also work out the collective unconventional photon blockade (UCPB) and get two kinds of giant nonreciprocal UCPBs (NUCPBs) in the weak-driving approximation. Results show that we can employ $N$ noninteracting bosonic atoms to generate a collective UCPB instead of a monoatomic UCPB as the UCPB conditions do not vary with the number of atoms. Furthermore, the forward giant NUCPB only occurring for $N$ larger than a certain number as well as the backward giant NUCPB are controllable by the cavity asymmetry and by the number of atoms. Our findings suggest a prospective approach to the generation of quantum nonreciprocity by $N$ identical atoms.
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    High peak power mini-array quantum cascade lasers operating in pulsed mode
    Yuhang Zhang(章宇航), Yupei Wang(王渝沛), Xiaoyue Luo(罗晓玥), Chenhao Qian(钱晨灏), Yang Cheng(程洋), Wu Zhao(赵武), Fangyuan Sun(孙方圆), Jun Wang(王俊), and Zheng-Ming Sun(孙正明)
    2025 (1):  14204-014204.  doi: 10.1088/1674-1056/ad886b
    摘要 ( 13 )  
    Broad area quantum cascade lasers (BA QCLs) have significant applications in many areas, but suffer from demanding pulse operating conditions and poor beam quality due to heat accumulation and generation of high order modes. A structure of mini-array is adopted to improve the heat dissipation capacity and beam quality of BA QCLs. The active region is etched to form a multi-emitter and the channels are filled with InP:Fe, which acts as a lateral heat dissipation channel to improve the lateral heat dissipation efficiency. A device with $\lambda \sim 4.8 \upmu$m, a peak output power of 122 W at 1.2% duty cycle with a pulse of 1.5 $\upmu $s is obtained in room temperature, with far-field single-lobed distribution. This result allows BA QCLs to obtain high peak power at wider pump pulse widths and higher duty cycle conditions, promotes the application of the mid-infrared laser operating in pulsed mode in the field of standoff photoacoustic chemical detection, space optical communication, and so on.
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    Femtosecond mode-locking and soliton molecule generation based on a GaAs saturable absorber
    Chen-Yan Zhang(张辰妍), Xin-He Dou(窦鑫河), Zhen Chen(陈震), Jing-Han Zhao(赵靖涵), Wei Sun(孙薇), Ze-Yu Fan(樊泽宇), Tao Zhang(张涛), Hao Teng(滕浩), and Zhi-Guo Lv(吕志国)
    2025 (1):  14205-014205.  doi: 10.1088/1674-1056/ad8db3
    摘要 ( 33 )   PDF(1401KB) ( 9 )  
    In the last few years, research on advanced ultrafast photonic devices has attracted great interest from laser physicists. As a semiconductor material with excellent nonlinear saturation absorption characteristics, GaAs has been used in solid-state and fiber lasers as a mode-locker. However, the pulse widths that have been reported in the searchable published literature are all long and the shortest is tens of picoseconds. Femtosecond pulse widths, desired for a variety of applications, have not yet been reported in GaAs-based pulsed lasers. In this work, we further explore the nonlinear characteristics of GaAs that has been magnetron sputtered onto the surface of a tapered fiber and its application in the generation of femtosecond lasing via effective dispersion optimization and nonlinearity management. With the enhanced interaction between evanescent waves and GaAs nanosheets, mode-locked soliton pulses as short as 830 fs are generated at repetition rates of 4.64 MHz. As far as we know, this is the first time that femtosecond-level pulses have been generated with a GaAs-based saturable absorber. In addition, soliton molecules, including in the dual-pulse state, are also realized under stronger pumping. This work demonstrates that GaAs-based photonic devices have good application prospects in effective polymorphous ultrashort pulsed laser generation.
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    Four-wave mixing Bragg scattering for small frequency shift from silicon coupled microrings
    Chang Zhao(赵畅), Chao Wu(吴超), Pingyu Zhu(朱枰谕), Yuxing Du(杜昱星), Yan Wang(王焱), Miaomiao Yu(余苗苗), Kaikai Zhang(张凯凯), and Ping Xu(徐平)
    2025 (1):  14206-014206.  doi: 10.1088/1674-1056/ad8a4f
    摘要 ( 20 )   PDF(1138KB) ( 24 )  
    Frequency conversion is pivotal in nonlinear optics and quantum optics for manipulating and translating light signals across different wavelength regimes. Achieving frequency conversion between two light beams with a small frequency interval is a central challenge. In this work, we design a pair of coupled silicon microrings wherein coupled-induced mode-splitting exists to achieve a small frequency shift by the process of four-wave mixing Bragg scattering. As an example, the signal can be up or down converted to the idler which is 15.5 GHz spaced when two pumps align with another pair of split resonances. The results unveil the potential of coupled microring resonators for small interval frequency conversion in a high-fidelity, all-optical, and signal processing quantum frequency interface.
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    Lamb wave TDTE super-resolution imaging assisted by deep learning
    Liu-Jia Sun(孙刘家), Qing-Bang Han(韩庆邦), and Qi-Lin Jin(靳琪琳)
    2025 (1):  14301-014301.  doi: 10.1088/1674-1056/ad886d
    摘要 ( 3 )   PDF(1589KB) ( 0 )  
    Ultrasonic Lamb waves undergo complex mode conversion and diffraction at non-penetrating defects, such as plate corrosion and cracks. Lamb wave imaging has a resolution limit due to the guided wave dispersion characteristics and Rayleigh criterion limitations. In this paper, a full convolutional network is designed to segment and reconstruct the received signals, enabling the automatic identification of target modalities. This approach eliminates clutter and mode conversion interference when calculating direct and accompanying acoustic fields in time-domain topological energy (TDTE) imaging. Subsequently, the measured accompanying acoustic field is reversed for adaptive focusing on defects and enhance the imaging quality. To circumvent the limitations of the Rayleigh criterion, the direct acoustic field and the accompanying acoustic field were fused to characterize the pixel distribution in the imaging region, achieving Lamb wave super-resolution imaging. Experimental results indicate that compared to the sign coherence factor-total focusing method (SCF-TFM), the proposed method achieves a 31.41% improvement in lateral resolution and a 29.53% increase in signal-to-noise ratio for single-blind-hole defects. In the case of multiple-blind-hole defects with spacings greater than the Rayleigh criterion resolution limit, it exhibits a 27.23% enhancement in signal-to-noise ratio. On the contrary, when the defect spacings are relatively smaller than the limit, this method has a higher resolution limit than SCF-TFM in super-resolution imaging.
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    High-efficiency wide-angle anomalous refraction with acoustic metagrating
    Kangyao Sun(孙康瑶), Yuancheng Fan(樊元成), Zhehao Ye(叶哲浩), Jiahui Li(李嘉荟), Quanhong Fu(付全红), Yali Zeng(曾雅丽), and Fuli Zhang(张富利)
    2025 (1):  14302-014302.  doi: 10.1088/1674-1056/ad8db6
    摘要 ( 15 )  
    The emergent metagrating, with its unique and flexible beam shaping capabilities, offers new paths to efficient modulation of acoustic waves. In this work, an acoustic metagrating is demonstrated for high-efficiency and wide-angle anomalous refraction. It is shown that the normal reflection and transmission can be totally suppressed by properly modulating the amplitude and phase characteristics of the metagrating supercells for high-efficiency anomalous refraction. The anomalous refraction behavior is achieved in the wide range of incident angles from 28$^\circ$ to 78$^\circ$, and the efficiency of $-1$st order diffraction is higher than 90% by finely designing the metagrating structure. The anomalous refraction behaviors are verified experimentally at incidence angle of 28$^\circ$, 45$^\circ$, and 78$^\circ$, respectively. The demonstrated metagrating is anticipated to possess efficient wide-angle composite wavefront engineering applications in such fields as communications.
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    Overcoming bandwidth limitations in space-coiled acoustic metamaterials through inclined perforated plate design
    Jixin Liu(刘继鑫), Fengmin Wu(吴丰民), Ting Li(李婷), Junjun Wang(王军军), Xinye Zou(邹欣晔), and Dong Zhang(章东)
    2025 (1):  14303-014303.  doi: 10.1088/1674-1056/ad8fa2
    摘要 ( 11 )  
    Traditional space-coiled acoustic metamaterials have been widely used in the fields of low-frequency sound absorption and noise reduction. However, they have limitations in terms of low-frequency absorption bandwidth, and the weak coupling effect under complex coiled structures also limits their applications. In this work, we introduce the composite structure changing the characteristic impedance of acoustic metamaterials to enhance the coupling effect. Meanwhile, the perforated plates with inclined design instead of traditional partitions greatly improve the sound absorption. The model and method designed in this paper show significant innovation in enhancing low-frequency absorption performance.
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    Stable nanobubbles on ordered water monolayer near ionic model surfaces
    Luyao Huang(黄璐瑶), Cheng Ling(凌澄), Limin Zhou(周利民), Wenlong Liang(梁文龙), Yujie Huang(黄雨婕), Lijuan Zhang(张立娟), Phornphimon Maitarad, Dengsong Zhang(张登松), and Chunlei Wang(王春雷)
    2025 (1):  14701-014701.  doi: 10.1088/1674-1056/ad989d
    摘要 ( 4 )   PDF(1121KB) ( 0 )  
    The stable nanobubbles adhered to mineral surfaces may facilitate their efficient separation via flotation in the mining industry. However, the state of nanobubbles on mineral solid surfaces is still elusive. In this study, molecular dynamics (MD) simulations are employed to examine mineral-like model surfaces with varying degrees of hydrophobicity, modulated by surface charges, to elucidate the adsorption behavior of nanobubbles at the interface. Our findings not only contribute to the fundamental understanding of nanobubbles but also have potential applications in the mining industry. We observed that as the surface charge increases, the contact angle of the nanobubbles increases accordingly with shape transformation from a pancake-like gas film to a cap-like shape, and ultimately forming a stable nanobubble upon an ordered water monolayer. When the solid-water interactions are weak with a small partial charge, the hydrophobic gas (N$_{2}$) molecules accumulate near the solid surfaces. However, we have found, for the first time, that gas molecules assemble a nanobubble on the water monolayer adjacent to the solid surfaces with large partial charges. Such phenomena are attributed to the formation of a hydrophobic water monolayer with a hydrogen bond network structure near the surface.
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    Non-uniform electron density estimation based on electromagnetic wave attenuation in plasma
    Zhaoying Wang(王召迎), Lixin Guo(郭立新), Maixia Fu(付麦霞), Shaoshuai Guo(郭韶帅), and Yinsheng Li(李寅生)
    2025 (1):  15201-015201.  doi: 10.1088/1674-1056/ad9454
    摘要 ( 8 )  
    The surface of a high-speed vehicle reentering the atmosphere is surrounded by plasma sheath. Due to the influence of the inhomogeneous flow field around the vehicle, understanding the electromagnetic properties of the plasma sheath can be challenging. Obtaining the electron density of the plasma sheath is crucial for understanding and achieving plasma stealth of vehicles. In this work, the relationship between electromagnetic wave attenuation and electron density is deduced theoretically. The attenuation distribution along the propagation path is found to be proportional to the integral of the plasma electron density. This result is used to predict the electron density profile. Furthermore, the average electron density is obtained using a back-propagation neural network algorithm. Finally, the spatial distribution of the electron density can be determined from the average electron density and the normalized derivative of attenuation with respect to the propagation depth. Compared to traditional probe measurement methods, the proposed approach not only improves efficiency but also preserves the integrity of the plasma environment.
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    Relaxation model for a homogeneous plasmas with spherically symmetric velocity space
    Yanpeng Wang(王彦鹏), Jianyuan Xiao(肖建元), Xianhao Rao(饶贤昊), Pengfei Zhang(张鹏飞), Yolbarsop Adil(阿迪里), and Ge Zhuang(庄革)
    2025 (1):  15202-015202.  doi: 10.1088/1674-1056/ad9455
    摘要 ( 4 )   PDF(500KB) ( 0 )  
    We derive the transport equations from the Vlasov-Fokker-Planck equation when the velocity space is spherically symmetric. The Shkarofsky's form of Fokker-Planck-Rosenbluth collision operator is employed in the Vlasov-Fokker-Planck equation. A closed-form relaxation model for homogeneous plasmas could be presented in terms of Gauss hypergeometric ${}_2$F$_1$ functions. This has been accomplished based on the Maxwellian mixture model. Furthermore, we demonstrate that classic models such as two-temperature thermal equilibrium model and thermodynamic equilibrium model are special cases of our relaxation model and the zeroth-order Braginskii heat transfer model can also be derived. The present relaxation model is a nonequilibrium model based on the hypothesis that the plasmas system possesses finitely distinguishable independent features, without relying on the conventional near-equilibrium assumption.
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    Observation of Weibel magnetic fields in laser-produced interpenetrating flows
    Chuanqi Shi(施川奇), Dawei Yuan(袁大伟), Wei Sun(孙伟), Yapeng Zhang(张雅芃), Zhijie Qiu(邱志杰), Huigang Wei(魏会冈), Zhe Zhang(张喆), Xiaohui Yuan(远晓辉), and Gang Zhao(赵刚)
    2025 (1):  15203-015203.  doi: 10.1088/1674-1056/ad94e4
    摘要 ( 6 )  
    Weibel instability is a promising candidate mechanism for collisionless shock formation in astrophysical systems. Capturing the underlying physics of Weibel instability will help us to understand the astrophysical shock formation, magnetic field generation and amplification, particle acceleration, and so on. Laboratory astrophysics, provides a new way to study these microphysics in controlled conditions. At Shenguang-II laser facility, the interpenetrating plasma flows are generated by eight laser beams irradiating a pair of opposing foils to mimic the supernova explosion and the ejecta sweeping up the surrounding medium. Evolution of collisionless interpenetrating plasma flows is observed using optical diagnostics. Filamentary structures appear in the interaction region and the associated magnetic strength is measured about 40 T. Theoretical analysis and simulations indicate that these characteristics are induced by nonlinear Weibel instability.
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    Database of ternary amorphous alloys based on machine learning
    Xuhe Gong(巩旭菏), Ran Li(李然), Ruijuan Xiao(肖睿娟), Tao Zhang(张涛), and Hong Li(李泓)
    2025 (1):  16101-016101.  doi: 10.1088/1674-1056/ad8ec8
    摘要 ( 25 )   PDF(2354KB) ( 7 )  
    The unique long-range disordered atomic arrangement inherent in amorphous materials endows them with a range of superior properties, rendering them highly promising for applications in catalysis, medicine, and battery technology, among other fields. Since not all materials can be synthesized into an amorphous structure, the composition design of amorphous materials holds significant importance. Machine learning offers a valuable alternative to traditional “trial-and-error” methods by predicting properties through experimental data, thus providing efficient guidance in material design. In this study, we develop a machine learning workflow to predict the critical casting diameter, glass transition temperature, and Young's modulus for 45 ternary reported amorphous alloy systems. The predicted results have been organized into a database, enabling direct retrieval of predicted values based on compositional information. Furthermore, the applications of high glass forming ability region screening for specified system, multi-property target system screening and high glass forming ability region search through iteration are also demonstrated. By utilizing machine learning predictions, researchers can effectively narrow the experimental scope and expedite the exploration of compositions.
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    Microstructure and magnetic properties of FeCoZr(Mo)BGe nanocrystalline alloys
    Wanqiu Yu(于万秋), Yanxiang Sun(孙筵翔), Lihua Liu(刘立华), and Pingli Zhang(张平丽)
    2025 (1):  16102-016102.  doi: 10.1088/1674-1056/ad5a77
    摘要 ( 20 )  
    The microstructure and magnetic properties of Fe$_{40}$Co$_{40}$Zr$_{9}$B$_{10}$Ge$_{1}$ (Mo-free) and Fe$_{40}$Co$_{40}$Zr$_{5}$Mo$_{4}$B$_{10}$Ge$_{1}$ (Mo-containing) nanocrystalline alloys, prepared using an amorphous crystallization method, were investigated. Mo addition affects the crystallization of the Fe$_{40}$Co$_{40}$Zr$_{9}$B$_{10}$Ge$_{1}$ amorphous alloy and decreases the grain size of the $\alpha $-Fe(Co) phase below 650 $^\circ$C. For the Mo-free alloy annealed at 600 $^\circ$C and the Mo-containing alloy annealed at 575 $^\circ$C, with a single $\alpha $-Fe(Co) crystallization phase and approximately similar crystallization volume fractions, the Mo-containing alloy showed smaller, more regularly shaped grains and a significantly narrower grain-size distribution than the Mo-free alloy. The Fe and Co contents in the nanograins of the two alloys also differed. For the Mo-free alloy, a higher concentration of Co distributed in the residual amorphous matrix. For the Mo-containing alloy, a higher concentration Co dissolved in the nanograins. The specific saturation magnetization and coercivity of the Mo-free alloy were 1.05- and 1.59-times higher than those of the Mo-containing alloy, respectively.
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    Stable structures and properties of Ru2Al5
    Jing Luo(罗晶), Meiguang Zhang(张美光), Xiaofei Jia(贾晓菲), and Qun Wei(魏群)
    2025 (1):  16301-016301.  doi: 10.1088/1674-1056/ad92fe
    摘要 ( 12 )  
    Novel ordered intermetallic compounds have stimulated much interest. Ru-Al alloys are a prominent class of high-temperature structural materials, but the experimentally reported crystal structure of the intermetallic Ru$_{2}$Al$_{5}$ phase remains elusive and debatable. To resolve this controversy, we extensively explored the crystal structures of Ru$_{2}$Al$_{5}$ using first-principles calculations combined with crystal structure prediction technique. Among the calculated x-ray diffraction patterns and lattice parameters of five candidate Ru$_{2}$Al$_{5}$ structures, those of the orthorhombic $Pmmn$ structure best aligned with recent experimental results. The structural stabilities of the five Ru$_{2}$Al$_{5}$ structures were confirmed through formation energy, elastic constants, and phonon spectrum calculations. We also comprehensively analyzed the mechanical and electronic properties of the five candidates. This work can guide the exploration of novel ordered intermetallic compounds in Ru-Al alloys.
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    Interparticle-friction-induced anomalous colloid structure
    Fuzhou Liu(刘福洲), Yu Ding(丁宇), Longfei Li(黎龙飞), Ke Cheng(程可), Fangfu Ye(叶方富), and Mingcheng Yang(杨明成)
    2025 (1):  16401-016401.  doi: 10.1088/1674-1056/ad9300
    摘要 ( 5 )   PDF(6802KB) ( 1 )  
    Interparticle frictional interactions are ubiquitous in colloidal systems, exerting a profound influence on their structural and physical attributes. In this study, we employed Brownian dynamics simulations to explore the non-equilibrium dynamics in colloidal systems, focusing particularly on the role of tangential friction and its influence on the macroscopic physical properties of colloids. We found that the disruption of instantaneous time-reversal symmetry by tangential frictional interactions can trigger the self-assembly of colloidal systems into intricate network configurations, and these novel structures exhibit unique depletion force and rheological properties that set them apart from traditional colloidal gel systems. These findings not only help deepen our comprehension of the self-assembly phenomena in non-equilibrium colloidal systems but also offer fresh insights for the development of colloidal materials with tailored characteristics.
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    Emergent 3×3 charge order on the Cs reconstruction of kagome superconductor CsV3Sb5
    Xianghe Han(韩相和), Zhongyi Cao(曹钟一), Zihao Huang(黄子豪), Zhen Zhao(赵振), Haitao Yang(杨海涛), Hui Chen(陈辉), and Hong-Jun Gao(高鸿钧)
    2025 (1):  16801-016801.  doi: 10.1088/1674-1056/ad8fa1
    摘要 ( 24 )   PDF(845KB) ( 8 )  
    The alkali adatoms with controlled coverage on the surface have been demonstrated to effectively tune the surface band of quantum materials through in situ electron doping. However, the interplay of orderly arranged alkali adatoms with the surface states of quantum materials remains unexplored. Here, by using low-temperature scanning tunneling microscopy/spectroscopy (STM/S), we observed the emergent 3$\times$3 super modulation of electronic states on the $\sqrt 3\times\sqrt 3R30^\circ$ (R3) Cs ordered surface of kagome superconductor CsV$_{3}$Sb$_{5}$. The nondispersive 3$\times$3 superlattice at R3 ordered surface shows contrast inversion in positive and negative differential conductance maps, indicating a charge order origin. The 3$\times$3 charge order is suppressed with increasing temperature and undetectable at a critical temperature of $\sim 62$ K. Furthermore, in the Ta substituted sample CsV$_{2.6}$Ta$_{0.4}$Sb$_{5}$, where long-range 2$\times$2$\times$2 charge density wave is significantly suppressed, the 3$\times$3 charge order on the R3 ordered surface becomes blurred and much weaker than that in the undoped sample. It indicates that the 3$\times$3 charge order on the R3 ordered surface is directly correlated to the bulk charge density waves in CsV$_{3}$Sb$_{5}$. Our work provides a new platform for understanding and manipulating the cascade of charge orders in kagome superconductors.
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    Combining machine learning algorithms with traditional methods for resolving the atomic-scale dynamic structure of monolayer MoS2 in high-resolution transmission electron microscopy
    Yu Meng(蒙宇), Shuya Wang(王淑雅), Xibiao Ren(任锡标), Han Xue(薛涵), Xuejun Yue(岳学军), Chuanhong Jin(金传洪), Shanggang Lin(林上港), and Fang Lin(林芳)
    2025 (1):  16802-016802.  doi: 10.1088/1674-1056/ad9ba3
    摘要 ( 8 )   PDF(3392KB) ( 0 )  
    High-resolution transmission electron microscopy (HRTEM) promises rapid atomic-scale dynamic structure imaging. Yet, the precision limitations of aberration parameters and the challenge of eliminating aberrations in $Cs$-corrected transmission electron microscopy constrain resolution. A machine learning algorithm is developed to determine the aberration parameters with higher precision from small, lattice-periodic crystal images. The proposed algorithm is then validated with simulated HRTEM images of graphene and applied to the experimental images of a molybdenum disulfide (MoS$_{2}$) monolayer with 25 variables (14 aberrations) resolved in wide ranges. Using these measured parameters, the phases of the exit-wave functions are reconstructed for each image in a focal series of MoS$_{2}$ monolayers. The images were acquired due to the unexpected movement of the specimen holder. Four-dimensional data extraction reveals time-varying atomic structures and ripple. In particular, the atomic evolution of the sulfur-vacancy point and line defects, as well as the edge structure near the amorphous, is visualized as the resolution has been improved from about 1.75 Å to 0.9 Å. This method can help salvage important transmission electron microscope images and is beneficial for the images obtained from electron microscopes with average stability.
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    Electronic band structures of topological kagome materials
    Man Li(李满), Huan Ma(马欢), Rui Lou(娄睿), and Shancai Wang(王善才)
    2025 (1):  17101-017101.  doi: 10.1088/1674-1056/ad925d
    摘要 ( 31 )   PDF(5475KB) ( 18 )  
    The kagome lattice has garnered significant attention due to its ability to host quantum spin Fermi liquid states. Recently, the combination of unique lattice geometry, electron-electron correlations, and adjustable magnetism in solid kagome materials has led to the discovery of numerous fascinating quantum properties. These include unconventional superconductivity, charge and spin density waves (CDW/SDW), pair density waves (PDW), and Chern insulator phases. These emergent states are closely associated with the distinctive characteristics of the kagome lattice's electronic structure, such as van Hove singularities, Dirac fermions, and flat bands, which can exhibit exotic quasi-particle excitations under different symmetries and magnetic conditions. Recently, various quantum kagome materials have been developed, typically consisting of kagome layers stacked along the $z$-axis with atoms either filling the geometric centers of the kagome lattice or embedded between the layers. In this topical review, we begin by introducing the fundamental properties of several kagome materials. To gain an in-depth understanding of the relationship between topology and correlation, we then discuss the complex phenomena observed in these systems. These include the simplest kagome metal $T_3X$, kagome intercalation metal $TX$, and the ternary compounds $AT_6X_6$ and $RT_3X_5$ ($A = {\rm Li}$, Mg, Ca, or rare earth; $T = {\rm V}$, Cr, Mn, Fe, Co, Ni; $X = {\rm Sn}$, Ge; $R = {\rm K}$, Rb, Cs). Finally, we provide a perspective on future experimental work in this field.
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    Valley-selective manipulation of moiré excitons through optical Stark effect
    Chenran Xu(徐晨燃), Jichen Zhou(周纪晨), Zhexu Shan(单哲旭), Wenjian Su(苏文健), Kenji Watanabe, Takashi Taniguchi, Dawei Wang(王大伟), and Yanhao Tang(汤衍浩)
    2025 (1):  17102-017102.  doi: 10.1088/1674-1056/ad7c32
    摘要 ( 24 )   PDF(4167KB) ( 7 )  
    Semiconductor moiré superlattices provide great platforms for exploring exotic collective excitations. Optical Stark effect, a shift of the electronic transition in the presence of a light field, provides an ultrafast and coherent method of manipulating matter states, which, however, has not been demonstrated in moiré materials. Here, we report the valley-selective optical Stark effect of moiré excitons in the WSe$_{2}$/WS$_{2}$ superlattice by using transient reflection spectroscopy. Prominent valley-selective energy shifts up to 7.8 meV have been observed for moiré excitons, corresponding to pseudo-magnetic fields as large as 34 T. Our results provide a route to coherently manipulate exotic states in moiré superlattices.
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    Classifying extended, localized and critical states in quasiperiodic lattices via unsupervised learning
    Bohan Zheng(郑博涵), Siyu Zhu(朱思宇), Xingping Zhou(周兴平), and Tong Liu(刘通)
    2025 (1):  17103-017103.  doi: 10.1088/1674-1056/ad8cb9
    摘要 ( 19 )   PDF(1012KB) ( 8 )  
    Classification of quantum phases is one of the most important areas of research in condensed matter physics. In this work, we obtain the phase diagram of one-dimensional quasiperiodic models via unsupervised learning. Firstly, we choose two advanced unsupervised learning algorithms, namely, density-based spatial clustering of applications with noise (DBSCAN) and ordering points to identify the clustering structure (OPTICS), to explore the distinct phases of the Aubry-André-Harper model and the quasiperiodic p-wave model. The unsupervised learning results match well with those obtained through traditional numerical diagonalization. Finally, we assess similarity across different algorithms and find that the highest degree of similarity between the results of unsupervised learning algorithms and those of traditional algorithms exceeds 98%. Our work sheds light on applications of unsupervised learning for phase classification.
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    Chiral phonons of honeycomb-type bilayer Wigner crystals
    Dingrui Yang(杨丁睿), Lingyi Li(李令仪), Na Zhang(张娜), and Hongyi Yu(俞弘毅)
    2025 (1):  17301-017301.  doi: 10.1088/1674-1056/ad8eca
    摘要 ( 27 )   PDF(1168KB) ( 10 )  
    We theoretically investigated the chiral phonons of honeycomb-type bilayer Wigner crystals recently discovered in van der Waals structures of layered transition metal dichalcogenides. These chiral phonons can emerge under the inversion symmetry breaking introduced by an effective mass imbalance between the two layers or a moiré potential in one layer, as well as under the time-reversal symmetry breaking realized by applying a magnetic field. Considering the wide tunability of layered materials, the frequencies and chirality of phonons can both be tuned by varying the system parameters. These findings suggest that bilayer honeycomb-type Wigner crystals can serve as an exciting new platform for studying chiral phonons.
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    Phase changings in the surface layers of Td-WTe2 driven by alkali-metal deposition
    Yu Zhu(朱玉), Zheng-Guo Wang(王政国), Yu-Jing Ren(任宇靖), Peng-Hao Yuan(袁鹏浩), Jing-Zhi Chen(陈景芝), Yi Ou(欧仪), Li-Li Meng(孟丽丽), and Yan Zhang(张焱)
    2025 (1):  17302-017302.  doi: 10.1088/1674-1056/ad9e9e
    摘要 ( 13 )  
    The discovery of phase changings in two-dimensional (2D) materials driven by external stimuli not only helps to understand the various intriguing phases in 2D materials but also provides directions for constructing new functional devices. Here, by combining angle-resolved photoemission spectroscopy (ARPES) and \textit{in-situ} alkali-metal deposition, we studied how alkali-metal adatoms affect the electronic structure of T$_{\rm d}$-WTe$_{2}$ on two different cleaved surfaces. We found that depending on the polarization direction of the cleaved surface, the alkali-metal deposition triggered two successive phase transitions on one surface of WTe$_{2}$, while on the other surface, no phase transition was found. We attributed the observed phase transitions to a T$_{\rm d\uparrow }$-1T$'$-T$_{\rm d\downarrow }$ structural transition driven by an alkali-metal induced sliding of WTe$_{2}$ layers. By comparing the band structure obtained in different structural phases of WTe$_{2}$, we found that the evolution of band structure across different phases is characterized by an energy scale that could be related to the degree of orbital hybridization between two adjacent WTe$_{2}$ layers. Our results demonstrate a method that manipulates the surface structure of bulk 2D materials. It also builds a direct correlation between the electronic structure and the degree of interlayer misalignment in this intriguing 2D material.
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    Intermediately coupled type-II superconductivity in a La-based kagome metal La3Al
    Yingpeng Yu(于英鹏), Zhaolong Liu(刘兆龙), Zhaoxu Chen(陈昭旭), Qi Li(李琦), Yulong Wang(王玉龙), Xuhui Wang(王旭辉), Chunsheng Gong(龚春生), Zhaotong Zhuang(庄照通), Bin-Bin Ruan(阮彬彬), Huifen Ren(任会芬), Peijie Sun(孙培杰), Jian-Gang Guo(郭建刚), and Shifeng Jin(金士锋)
    2025 (1):  17401-017401.  doi: 10.1088/1674-1056/ad8f9f
    摘要 ( 16 )  
    We present a comprehensive investigation into the superconducting properties of La$_{3}$Al, a La-based metal with a kagome structure. La$_{3}$Al crystallizes in a Ni$_{3}$Sn-type crystal structure (space group $P6_{3}/mmc$), where the La atoms form a kagome lattice. Resistivity measurements reveal superconducting transition with $T_{\rm c}^{\rm onset}=6.37$ K and $T_{\rm c}^{\rm zero}=6.18$ K. In magnetic susceptibility measurements, the superconducting transition is observed at 6.16 K. The lower and upper critical fields are determined to be 22.17 mT and 6.69 T, respectively. Heat capacity measurements confirm the bulk superconductivity, showing a normalized specific heat change of ${\Delta C_{\rm e}} / (\gamma T_{\rm c})=2.16$ and an electron-phonon coupling strength of $\lambda_{\rm ep} =0.9 2$. DFT calculations reveal the intricate band structure of La$_{3}$Al. The notable specific heat jump, coupled with the electron-phonon coupling strength $\lambda_{\rm ep}$, indicates that La$_{3}$Al exhibits characteristics of an intermediately coupled type-II superconductor.
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    Electronic structure, elasticity, magnetism of Mn2XIn(X = Fe, Co) full Heusler compounds under biaxial strain: First-principles calculations
    Shiran Gao(皋世苒), Chengyang Zhao(赵成洋), Xinzhuo Zhang(张欣卓), Wen Qiao(乔文), Shiming Yan(颜士明), Ru Bai(白茹), and Tiejun Zhou(周铁军)
    2025 (1):  17501-017501.  doi: 10.1088/1674-1056/ad8ec5
    摘要 ( 2 )   PDF(2689KB) ( 0 )  
    The electronic structure, elasticity, and magnetic properties of the Mn$_{2}X$In ($X={\rm Fe}$, Co) full-Heusler compounds are comprehensively investigated via first-principles calculations. The calculated elastic constants indicate that both Mn$_{2}$FeIn and Mn$_{2}$CoIn possess ductility. At the optimal lattice constants, the magnetic moments are found to be 1.40 $\mu_{\rm B}$/f.u. for Mn$_{2}$FeIn and 1.69 $\mu_{\rm B}$/f.u. for Mn$_{2}$CoIn. Under the biaxial strain ranging from $-2$% to 5%, Mn$_{2}$FeIn demonstrates a remarkable variation in the spin polarization, spanning from $-2$% to 74%, positioning it as a promising candidate for applications in spintronic devices. Analysis of the electronic structure reveals that the change in spin polarization under strain is due to the shift of the spin-down states at the Fermi surface. Additionally, under biaxial strain, the magnetic anisotropy of Mn$_{2}$FeIn undergoes a transition of easy-axis direction. Utilizing second-order perturbation theory and electronic structure analysis, the variation in magnetic anisotropy with strain can be attributed to changes of d-orbital states near the Fermi surface.
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    Moderate electron-spin interaction in Fe-intercalated NbSe2
    Qiao-Yu Liu(刘乔宇), Jian-Li Bai(白建利), Qing-Xin Dong(董庆新), Li-Bo Zhang(张黎博), Jing-Wen Cheng(程靖雯), Pin-Yu Liu(刘品宇), Cun-Dong Li(李存东), Yu Huang(黄宇), Ying-Rui Sun(孙英睿), Zhi-An Ren(任治安), and Gen-Fu Chen(陈根富)
    2025 (1):  17502-017502.  doi: 10.1088/1674-1056/ad9735
    摘要 ( 5 )   PDF(991KB) ( 0 )  
    The interaction between charge and spin degrees of freedom has always been the central issue of condensed matter physics, and transition metal dichalcogenides (TMDs) provide an ideal platform to study it benefiting from their highly tunable properties. In this article, the influence of Fe intercalation in NbSe$_{2}$ was elaborately investigated using a combination of techniques. Magnetic studies have shown that the insertion of Fe atoms induces an antiferromagnetic state in which the easy axis aligns out of the plane. The sign reversal of the magnetoresistance across the Neel temperature can be satisfactorily explained by the moderate interaction between electrons and local spins. The Hall and Seebeck measurements reveal a multi-band nature, and the contribution of various phonon scattering processes is discussed based on the thermal conductivity and specific heat data.
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    Manipulating optical and electronic properties through interfacial ferroelectricity
    Yulu Liu(刘钰璐), Gan Liu(刘敢), and Xiaoxiang Xi(奚啸翔)
    2025 (1):  17701-017701.  doi: 10.1088/1674-1056/ad9456
    摘要 ( 27 )   PDF(2250KB) ( 11 )  
    Interfacial ferroelectricity is a recently established mechanism for generating spontaneous reversible electric polarization, arising from the charge transfer between stacked van der Waals layered atomic crystals. It has been realized in both naturally formed multilayer crystals and moiré superlattices. Owing to the large number of material choices and combinations, this approach is highly versatile, greatly expanding the scope of ultrathin ferroelectrics. A key advantage of interfacial ferroelectricity is its potential to couple with preexisting properties of the constituent layers, enabling their electrical manipulation through ferroelectric switching and paving the way for advanced device functionalities. This review article summarizes recent experimental progress in interfacial ferroelectricity, with an emphasis on its coupling with a variety of electronic properties. After introducing the underlying mechanism of interfacial ferroelectricity and the range of material systems discovered to date, we highlight selected examples showcasing ferroelectric control of excitonic optical properties, Berry curvature effects, and superconductivity. We also discuss the challenges and opportunities that await further studies in this field.
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    Optimization of Skanavi model and its application to high permittivity materials
    Hao Luo(罗昊), Xinrui Qin(秦新瑞), Kejia Geng(耿可佳), Cuncun Kong(孔存存), and Pengfei Cheng(成鹏飞)
    2025 (1):  17702-017702.  doi: 10.1088/1674-1056/ad9ba0
    摘要 ( 15 )  
    A novel method is introduced to optimize the traditional Skanavi model by decomposing the electric field of molecules into the electric field of ions and quantitatively describing the ionic-scale electric field by the structural coefficient of the effective electric field. Furthermore, the optimization of the Skanavi model is demonstrated and the ferroelectric phase transition of BaTiO$_3$ crystals is revealed by calculating the optical and static permittivities of BaTiO$_{3}$, CaTiO$_{3}$, and SrTiO$_{3}$ crystals and the structure coefficients of the effective electric field of BT crystals after Ti$^{4+}$ displacement. This research compensates for the deficiencies of the traditional Skanavi model and refines the theoretical framework for analyzing dielectric properties in high permittivity materials.
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    Intensity enhancement of Raman active and forbidden modes induced by naturally occurred hot spot at GaAs edge
    Tao Liu(刘涛), Miao-Ling Lin(林妙玲), Da Meng(孟达), Xin Cong(从鑫), Qiang Kan(阚强), Jiang-Bin Wu(吴江滨), and Ping-Heng Tan(谭平恒)
    2025 (1):  17801-017801.  doi: 10.1088/1674-1056/ad9ff9
    摘要 ( 7 )   PDF(4871KB) ( 0 )  
    Edge structures are ubiquitous in the processing and fabrication of various optoelectronic devices. Novel physical properties and enhanced light-matter interactions are anticipated to occur at crystal edges due to the broken spatial translational symmetry. However, the intensity of first-order Raman scattering at crystal edges has been rarely explored, although the mechanical stress and edge characteristics have been thoroughly studied by the Raman peak shift and the spectral features of the edge-related Raman modes. Here, by taking GaAs crystal with a well-defined edge as an example, we reveal the intensity enhancement of Raman-active modes and the emergence of Raman-forbidden modes under specific polarization configurations at the edge. This is attributed to the presence of a hot spot at the edge due to the redistributed electromagnetic fields and electromagnetic wave propagations of incident laser and Raman signal near the edge, which are confirmed by the finite-difference time-domain simulations. Spatially-resolved Raman intensities of both Raman-active and Raman-forbidden modes near the edge are calculated based on the redistributed electromagnetic fields, which quantitatively reproduce the corresponding experimental results. These findings offer new insights into the intensity enhancement of Raman scattering at crystal edges and present a new avenue to manipulate light-matter interactions of crystal by manufacturing various types of edges and to characterize the edge structures in photonic and optoelectronic devices.
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    Plastic deformation mechanism of γ-phase U-Mo alloy studied by molecular dynamics simulations
    Wang Chang(王畅), Peng Peng(彭芃), and Lai-Wen Sheng(赖文生)
    2025 (1):  18101-018101.  doi: 10.1088/1674-1056/ad925e
    摘要 ( 6 )   PDF(779KB) ( 0 )  
    Uranium-molybdenum (U-Mo) alloys are critical for nuclear power generation and propulsion because of their superior thermal conductivity, irradiation stability, and anti-swelling properties. This study explores the plastic deformation mechanisms of $\gamma $-phase U-Mo alloys using molecular dynamics (MD) simulations. In the slip model, the generalized stacking fault energy (GSFE) and the modified Peierls-Nabarro (P-N) model are used to determine the competitive relationships among different slip systems. In the twinning model, the generalized plane fault energy (GPFE) is assessed to evaluate the competition between slip and twinning. The findings reveal that among the three slip systems, the {110}$\langle 111\rangle$ slip system is preferentially activated, while in the {112}$\langle 111\rangle$ system, twinning is favored over slip, as confirmed by MD tensile simulations conducted in various directions. Additionally, the impact of Mo content on deformation behavior is emphasized. Insights are provided for optimizing process conditions to avoid $\gamma \to \alpha''$ transitions, thereby maintaining a higher proportion of $\gamma $-phase U-Mo alloys for practical applications.
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    Atmospheric neutron single event effects for multiple convolutional neural networks based on 28-nm and 16-nm SoC
    Xu Zhao(赵旭), Xuecheng Du(杜雪成), Chao Ma(马超), Zhiliang Hu(胡志良), Weitao Yang(杨卫涛), and Bo Zheng(郑波)
    2025 (1):  18501-018501.  doi: 10.1088/1674-1056/ad8b38
    摘要 ( 4 )   PDF(964KB) ( 0 )  
    The single event effects (SEEs) evaluations caused by atmospheric neutrons were conducted on three different convolutional neural network (CNN) models (Yolov3, MNIST, and ResNet50) in the atmospheric neutron irradiation spectrometer (ANIS) at the China Spallation Neutron Source (CSNS). The Yolov3 and MNIST models were implemented on the XILINX 28-nm system-on-chip (SoC). Meanwhile, the Yolov3 and ResNet50 models were deployed on the XILINX 16-nm FinFET UltraScale+MPSoC. The atmospheric neutron SEEs on the tested CNN systems were comprehensively evaluated from six aspects, including chip type, network architecture, deployment methods, inference time, datasets, and the position of the anchor boxes. The various types of SEE soft errors, SEE cross-sections, and their distribution were analyzed to explore the radiation sensitivities and rules of 28-nm and 16-nm SoC. The current research can provide the technology support of radiation-resistant design of CNN system for developing and applying high-reliability, long-lifespan domestic artificial intelligence chips.
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    Gate-tunable high-responsivity photodiode based on 2D ambipolar semiconductor
    Wentao Yu(于文韬), Long Zhao(赵龙), Yanfei Gao(高延飞), Shiping Gao(高石平), Yuekun Yang(杨悦昆), Chen Pan(潘晨), Shi-Jun Liang(梁世军), and Bin Cheng(程斌)
    2025 (1):  18502-018502.  doi: 10.1088/1674-1056/ad9c44
    摘要 ( 13 )  
    Electrically tunable homojunctions based on ambipolar two-dimensional materials have attracted widespread attention in the field of intelligent vision. These devices exhibit inherent switchable positive and negative photovoltaic properties that effectively mimic the behavior of human retinal cells. However, the photovoltaic responsivity of most electrically tunable homojunctions remains significantly low due to the weak light absorption, making it challenging to meet the application requirements for high-sensitivity target detection in the field of intelligent vision. Here, we propose a gate-tunable photodiode based on two-dimensional ambipolar WSe$_{2}$ with an asymmetric gate electrode, achieving high photovoltaic responsivity. By adjusting the gate voltage and keeping bias voltage zero, we can dynamically realize reconfigurable n$^-$-p and n$^-$-n homojunction states, as well as gate-tunable photovoltaic response characteristics that range from positive to negative. The maximum photovoltaic responsivity of the electrically tunable WSe$_{2}$ homojunction is approximately 0.4 A/W, which is significantly larger than the previously reported value 0.1 A/W in homojunction devices. In addition, the responsivity can be further enhanced to approximately 1.0 A/W when the n-p photodiode operates in reverse bias mode, enabling high-sensitivity detection of targets. Our work paves the way for developing gate-tunable photodiodes with high photovoltaic responsivity and advancing high-performance intelligent vision technology.
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    Improving performance of screening MM/PBSA in protein-ligand interactions via machine learning
    Yuan-Qiang Chen(陈远强), Yao Xu(徐耀), Yu-Qiang Ma(马余强), and Hong-Ming Ding(丁泓铭)
    2025 (1):  18701-018701.  doi: 10.1088/1674-1056/ad8ecb
    摘要 ( 1 )   PDF(530KB) ( 0 )  
    Accurately estimating protein-ligand binding free energy is crucial for drug design and biophysics, yet remains a challenging task. In this study, we applied the screening molecular mechanics/Poisson-Boltzmann surface area (MM/PBSA) method in combination with various machine learning techniques to compute the binding free energies of protein-ligand interactions. Our results demonstrate that machine learning outperforms direct screening MM/PBSA calculations in predicting protein-ligand binding free energies. Notably, the random forest (RF) method exhibited the best predictive performance, with a Pearson correlation coefficient ($r_{\rm p}$) of 0.702 and a mean absolute error (MAE) of 1.379 kcal/mol. Furthermore, we analyzed feature importance rankings in the gradient boosting (GB), adaptive boosting (AdaBoost), and RF methods, and found that feature selection significantly impacted predictive performance. In particular, molecular weight (MW) and van der Waals (VDW) energies played a decisive role in the prediction. Overall, this study highlights the potential of combining machine learning methods with screening MM/PBSA for accurately predicting binding free energies in biosystems.
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    On load dependence of detachment rate of kinesin motor
    Xiao-Xuan Shi(史晓璇), Yao Wang(王瑶), Yu-Ru Liu(刘玉如), and Ping Xie(谢平)
    2025 (1):  18702-018702.  doi: 10.1088/1674-1056/ad8ec7
    摘要 ( 12 )  
    Kinesin is an archetypal microtubule-based molecular motor that can generate force to transport cargo in cells. The load dependence of the detachment rate is an important factor of the kinesin motor, the determination of which is critically related to the chemomechanical coupling mechanism of the motor. Here, we use three models for the load dependence of the detachment rate of the kinesin motor to study theoretically and numerically the maximal force generated and microtubule-attachment duration of the motor. By comparing the theoretical and numerical results with the available experimental data, we show that only one model can explain well the available experimental data, indicating that only this model can be applicable to the kinesin motor.
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    A physical memristor model for Pavlovian associative memory
    Jiale Lu(卢家乐), Haofeng Ran(冉皓丰), Dirui Xie(谢頔睿), Guangong Zhou(周广东), and Xiaofang Hu(胡小方)
    2025 (1):  18703-018703.  doi: 10.1088/1674-1056/ad8b37
    摘要 ( 22 )   PDF(1813KB) ( 4 )  
    Brain-inspired intelligence is considered to be a computational model with the most promising potential to overcome the shortcomings of the von Neumann architecture, making it a current research hotspot. Due to advantages such as nonvolatility, high density, low power consumption, and high response ratio, memristors are regarded as devices with promising applications in brain-inspired intelligence. This paper proposes a physical Ag/HfO$_{x}$/FeO$_{x}$/Pt memristor model. The Ag/HfO$_{x}$/FeO$_{x}$/Pt memristor is first fabricated using magnetron sputtering, and its internal principles and characteristics are then thoroughly analyzed. Furthermore, we construct a corresponding physical memristor model which achieves a simulation accuracy of up to 99.72% for the physical memristor. We design a fully functional Pavlovian associative memory circuit, realizing functions including generalization, primary differentiation, secondary differentiation, and forgetting. Finally, the circuit is validated through PSPICE simulation and analysis.
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    A fractional-order improved FitzHugh-Nagumo neuron model
    Pushpendra Kumar and Vedat Suat Erturk
    2025 (1):  18704-018704.  doi: 10.1088/1674-1056/ad8a46
    摘要 ( 16 )   PDF(951KB) ( 5 )  
    We propose a fractional-order improved FitzHugh-Nagumo (FHN) neuron model in terms of a generalized Caputo fractional derivative. Following the existence of a unique solution for the proposed model, we derive the numerical solution using a recently proposed L1 predictor-corrector method. The given method is based on the L1-type discretization algorithm and the spline interpolation scheme. We perform the error and stability analyses for the given method. We perform graphical simulations demonstrating that the proposed FHN neuron model generates rich electrical activities of periodic spiking patterns, chaotic patterns, and quasi-periodic patterns. The motivation behind proposing a fractional-order improved FHN neuron model is that such a system can provide a more nuanced description of the process with better understanding and simulation of the neuronal responses by incorporating memory effects and non-local dynamics, which are inherent to many biological systems.
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    Combining deep reinforcement learning with heuristics to solve the traveling salesman problem
    Li Hong(洪莉), Yu Liu(刘宇), Mengqiao Xu(徐梦俏), and Wenhui Deng(邓文慧)
    2025 (1):  18705-018705.  doi: 10.1088/1674-1056/ad95f1
    摘要 ( 14 )   PDF(381KB) ( 7 )  
    Recent studies employing deep learning to solve the traveling salesman problem (TSP) have mainly focused on learning construction heuristics. Such methods can improve TSP solutions, but still depend on additional programs. However, methods that focus on learning improvement heuristics to iteratively refine solutions remain insufficient. Traditional improvement heuristics are guided by a manually designed search strategy and may only achieve limited improvements. This paper proposes a novel framework for learning improvement heuristics, which automatically discovers better improvement policies for heuristics to iteratively solve the TSP. Our framework first designs a new architecture based on a transformer model to make the policy network parameterized, which introduces an action-dropout layer to prevent action selection from overfitting. It then proposes a deep reinforcement learning approach integrating a simulated annealing mechanism (named RL-SA) to learn the pairwise selected policy, aiming to improve the 2-opt algorithm's performance. The RL-SA leverages the whale optimization algorithm to generate initial solutions for better sampling efficiency and uses the Gaussian perturbation strategy to tackle the sparse reward problem of reinforcement learning. The experiment results show that the proposed approach is significantly superior to the state-of-the-art learning-based methods, and further reduces the gap between learning-based methods and highly optimized solvers in the benchmark datasets. Moreover, our pre-trained model M can be applied to guide the SA algorithm (named M-SA (ours)), which performs better than existing deep models in small-, medium-, and large-scale TSPLIB datasets. Additionally, the M-SA (ours) achieves excellent generalization performance in a real-world dataset on global liner shipping routes, with the optimization percentages in distance reduction ranging from 3.52% to 17.99%.
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    SolarDesign: An online photovoltaic device simulation and design platform
    Wei E. I. Sha(沙威), Xiaoyu Wang(王啸宇), Wenchao Chen(陈文超), Yuhao Fu(付钰豪), Lijun Zhang(张立军), Liang Tian(田亮), Minshen Lin(林敏慎), Shudi Jiao(焦书迪), Ting Xu(徐婷), Tiange Sun(孙天歌), and Dongxue Liu(刘冬雪)
    2025 (1):  18801-018801.  doi: 10.1088/1674-1056/ad9017
    摘要 ( 32 )   PDF(648KB) ( 16 )  
    SolarDesign (https://solardesign.cn/) is an online photovoltaic device simulation and design platform that provides engineering modeling analysis for crystalline silicon solar cells, as well as emerging high-efficiency solar cells such as organic, perovskite, and tandem cells. The platform offers user-updatable libraries of basic photovoltaic materials and devices, device-level multi-physics simulations involving optical-electrical-thermal interactions, and circuit-level compact model simulations based on detailed balance theory. Employing internationally advanced numerical methods, the platform accurately, rapidly, and efficiently solves optical absorption, electrical transport, and compact circuit models. It achieves multi-level photovoltaic simulation technology from “materials to devices to circuits” with fully independent intellectual property rights. Compared to commercial softwares, the platform achieves high accuracy and improves speed by more than an order of magnitude. Additionally, it can simulate unique electrical transport processes in emerging solar cells, such as quantum tunneling, exciton dissociation, and ion migration.
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    Accurate prediction of essential proteins using ensemble machine learning
    Dezhi Lu(鲁德志), Hao Wu(吴淏), Yutong Hou(侯俞彤), Yuncheng Wu(吴云成), Yuanyuan Liu(刘媛媛), and Jinwu Wang(王金武)
    2025 (1):  18901-018901.  doi: 10.1088/1674-1056/ad8db2
    摘要 ( 22 )   PDF(761KB) ( 4 )  
    Essential proteins are crucial for biological processes and can be identified through both experimental and computational methods. While experimental approaches are highly accurate, they often demand extensive time and resources. To address these challenges, we present a computational ensemble learning framework designed to identify essential proteins more efficiently. Our method begins by using node2vec to transform proteins in the protein-protein interaction (PPI) network into continuous, low-dimensional vectors. We also extract a range of features from protein sequences, including graph-theory-based, information-based, compositional, and physiochemical attributes. Additionally, we leverage deep learning techniques to analyze high-dimensional position-specific scoring matrices (PSSMs) and capture evolutionary information. We then combine these features for classification using various machine learning algorithms. To enhance performance, we integrate the outputs of these algorithms through ensemble methods such as voting, weighted averaging, and stacking. This approach effectively addresses data imbalances and improves both robustness and accuracy. Our ensemble learning framework achieves an AUC of 0.948 and an accuracy of 0.9252, outperforming other computational methods. These results demonstrate the effectiveness of our approach in accurately identifying essential proteins and highlight its superior feature extraction capabilities.
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    Dynamic partition of urban network considering congestion evolution based on random walk
    Zhen-Tong Feng(冯振通), Lele Zhang(张乐乐), Yong-Hong Wu(吴永洪), and Mao-Bin Hu(胡茂彬)
    2025 (1):  18902-018902.  doi: 10.1088/1674-1056/ad94e1
    摘要 ( 9 )  
    The successful application of perimeter control of urban traffic system strongly depends on the macroscopic fundamental diagram of the targeted region. Despite intensive studies on the partitioning of urban road networks, the dynamic partitioning of urban regions reflecting the propagation of congestion remains an open question. This paper proposes to partition the network into homogeneous sub-regions based on random walk algorithm. Starting from selected random walkers, the road network is partitioned from the early morning when congestion emerges. A modified Akaike information criterion is defined to find the optimal number of partitions. Region boundary adjustment algorithms are adopted to optimize the partitioning results to further ensure the correlation of partitions. The traffic data of Melbourne city are used to verify the effectiveness of the proposed partitioning method.
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    Experimental study on egress capacity of key facilities in pressurized oxygen-supplement compartments
    Kai-Qiang Wang(王凯强), Xue-Hua Song(宋雪华), Wei-Jun Liu(刘卫军), Kang Wen(文康), Zhi-Gang Shi(石志钢), Jun Zhang(张俊), Bin Yao(姚斌), and Wei-Guo Song(宋卫国)
    2025 (1):  18903-018903.  doi: 10.1088/1674-1056/ad94e2
    摘要 ( 2 )   PDF(1336KB) ( 0 )  
    Pressurized buildings have emerged as a novel architectural solution to alleviate altitude illness in high-altitude regions. Unlike conventional buildings, evacuation from this kind of building has to experience a depressurization time, which results in air expansion and heat absorption, creating a dense fog and impairing sight within the buildings. Evacuation experiments were performed in a pressurized oxygen-supplement compartment to investigate the pedestrian motion properties. Based on the questionnaires, participants reported varying degrees of symptoms such as ear blockage, reduced environmental noise, and dizziness, which had a measurable impact on their mobility. We focus on the evacuation parameters through three basic building components: staircases, pressure transition cabins, and escape windows. As the visibility in the compartment decreases from high to low, the movement patterns of pedestrian shift from triangular to single-file with a significant decline in evacuation efficiency. It is found that there is a linear relationship between evacuation time and the number of evacuees through escape windows. The pressure transition cabin is a crucial evacuation route in emergencies, and evacuation time is recommended as the key metric for assessing its effectiveness. These findings offer valuable insights for emergency evacuation strategies in pressurized buildings.
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    Dynamic modeling and analysis of brucellosis on metapopulation network: Heilongjiang as cases
    Xin Pei(裴鑫), Xuan-Li Wu(武绚丽), Pei Pei(裴沛), Ming-Tao Li(李明涛), Juan Zhang(张娟), and Xiu-Xiu Zhan(詹秀秀)
    2025 (1):  18904-018904.  doi: 10.1088/1674-1056/ad92ff
    摘要 ( 16 )   PDF(632KB) ( 3 )  
    Livestock transportation is a key factor that contributes to the spatial spread of brucellosis. To analyze the impact of sheep transportation on brucellosis transmission, we develop a human-sheep coupled brucellosis model within a metapopulation network framework. Theoretically, we examine the positively invariant set, the basic reproduction number, the existence, uniqueness, and stability of disease-free equilibrium and the existence of the endemic equilibrium of the model. For practical application, using Heilongjiang province as a case study, we simulate brucellosis transmission across 12 cities based on data using three network types: the BA network, the ER network, and homogeneous mixing network. The simulation results indicate that the network's average degree plays a role in the spread of brucellosis. For BA and ER networks, the basic reproduction number and cumulative incidence of brucellosis stabilize when the network's average degree reaches 4 or 5. In contrast, sheep transport in a homogeneous mixing network accelerates the cross-regional spread of brucellosis, whereas transportation in a BA network helps to control it effectively. Furthermore, the findings suggest that the movement of sheep is not always detrimental to controlling the spread of brucellosis. For cities with smaller sheep populations, such as Shuangyashan and Qitaihe, increasing the transport of sheep outward amplifies the spatial spread of the disease. In contrast, in cities with larger sheep populations, such as Qiqihar, Daqing, and Suihua, moderate sheep outflow can help reduce the spread. In addition, cities with large livestock populations play a dominant role in the overall transmission dynamics, underscoring the need for stricter supervision in these areas.
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