Chin. Phys. B

Practical algorithm for simulating thermal pure quantum states

Wei-Bo He(何伟博), Yun-Tong Yang(杨贇彤), and Hong-Gang Luo(罗洪刚)

Chin. Phys. B, 2026, 35 (1): 010101. DOI: 10.1088/1674-1056/ae1c21

Abstract ( 37 )

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The development of novel quantum many-body computational algorithms relies on robust benchmarking. However, generating such benchmarks is often hindered by the massive computational resources required for exact diagonalization or quantum Monte Carlo simulations, particularly at finite temperatures. In this work, we propose a new algorithm for obtaining thermal pure quantum states, which allows efficient computation of both mechanical and thermodynamic properties at finite temperatures. We implement this algorithm in our open-source C++ template library, Physica. Combining the improved algorithm with state-of-the-art software engineering, our implementation achieves high performance and numerical stability. As an example, we demonstrate that for the $4 \times 4$ Hubbard model, our method runs approximately $10^3$ times faster than $\mathcal{H}\varPhi$ 3.5.2. Moreover, the accessible temperature range is extended down to $\beta = 32$ across arbitrary doping levels. These advances significantly push forward the frontiers of benchmarking for quantum many-body systems.

Probabilistic distribution and stochastic P-bifurcation of a nonlinear energy-regenerative suspension system with time-delayed feedback control

Zhao-Bin Zeng(曾昭彬), Ya-Hui Sun(孙亚辉), and Yang Liu(刘洋)

Chin. Phys. B, 2026, 35 (1): 010201. DOI: 10.1088/1674-1056/ade669

Abstract ( 9 )

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Energy-regenerative suspension combined with piezoelectric and electromagnetic transduction has evolved into a core technological pathway in advancing automotive design paradigms. With the aim of improving energy harvesting performance, time-delayed feedback control is widely used in an energy-regenerative suspension system under different external disturbances in this paper. Meanwhile, limited research has addressed the stochastic dynamics of time-delayed nonlinear energy-regenerative suspension systems. Different from previous studies, this work studies the stochastic response and $P$-bifurcation of the nonlinear energy-regenerative suspension system with time-delayed feedback control. Firstly, an approximately equivalent dimension reduction system is established by the variable transformation method, and then the stationary probability density function of amplitude is obtained by the stochastic averaging method. Secondly, the precision of the method used in this work is verified by comparing the numerical solutions with the analytical results. Finally, based on the stationary probability density function, the influence of system parameters on stochastic $P$-bifurcation and the mean output power is discussed.

Preparation of digital-encoded and analog-encoded quantum states corresponding to matrix operations

Kaitian Gao(高凯天), Youlong Yang(杨有龙), and Zhenye Du(杜振叶)

Chin. Phys. B, 2026, 35 (1): 010202. DOI: 10.1088/1674-1056/ade3ad

Abstract ( 2 )

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Efficient implementation of fundamental matrix operations on quantum computers, such as matrix products and Hadamard operations, holds significant potential for accelerating machine learning algorithms. A critical prerequisite for quantum implementations is the effective encoding of classical data into quantum states. We propose two quantum computing frameworks for preparing the distinct encoded states corresponding to matrix operations, including the matrix product, matrix sum, matrix Hadamard product and division. Quantum algorithms based on the digital encoding computing framework are capable of implementing the matrix Hadamard operation with a time complexity of $O({\rm poly} \log(mn/\epsilon))$ and the matrix product with a time complexity of $O({\rm poly} \log (mnl/ \epsilon))$, achieving an exponential speedup in contrast to the classical methods of $O(mn)$ and $O(mnl)$. Quantum algorithms based on the analog-encoding framework are capable of implementing the matrix Hadamard operation with a time complexity of $O(k_{1} \sqrt{mn} \cdot {\rm poly} \log(mn/\epsilon))$ and the matrix product with a time complexity of $O(k_{2} \sqrt{l} \cdot {\rm poly} \log (mnl/ \epsilon))$, where $k_{1}$ and $k_{2}$ are coefficients correlated with the elements of the matrix, achieving a square speedup in contrast to the classical counterparts. As applications, we construct an oracle that can access the trace of a matrix within logarithmic time, and propose several algorithms to respectively estimate the trace of a matrix, the trace of the product of two matrices, and the trace inner product of two matrices within logarithmic time.

Exceptional point-induced knot structure transformations in non-Abelian braids

Lin-Sheng Bao(包淋升), Jia-Yun Ning(宁佳运), Ao-Qian Shi(史奥芊), Peng Peng(彭鹏), Zhen-Nan Wang(王瑱男), Chao Peng(彭超), Shuang-Chun Wen(文双春), and Jian-Jun Liu(刘建军)

Chin. Phys. B, 2026, 35 (1): 010203. DOI: 10.1088/1674-1056/ae2265

Abstract ( 25 )

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The strong connection between braids and knots provides valuable insights into studying the topological state and phase classification of various physical systems. The phenomenon of non-Hermitian (NH) two- and three-band braiding has received widespread attention. However, a systematic exploration and visualization of non-Abelian braiding and the associated knot transformations in four-band systems remains unexplored. Here, we propose a theoretical model of NH four-band braiding, provide its phase diagram, and establish its trivial, Abelian, and non-Abelian braiding rules. Additionally, we report on special knots, such as the Hopf and Solomon links in braided knots, and reveal that their transformations are accompanied by and mediated through exceptional points. Our work provides a detailed case for studying NH multiband braiding and knot structures in four-band systems, which could offer insights for topological photonics and analog information processing applications.

Unveiling the physical meaning of transformer attention in neural network quantum states: A conditional mutual information perspective

Tianyu Ruan(阮天雨), Bowen Kan(阚博文), Yixuan Sun(孙艺轩), Honghui Shang(商红慧), Shihua Zhang(张世华), and Jinlong Yang(杨金龙)

Chin. Phys. B, 2026, 35 (1): 010301. DOI: 10.1088/1674-1056/ae1118

Abstract ( 34 )

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Transformer-based neural-network quantum states (NNQS) have shown great promise in representing quantum many-body ground states, offering high flexibility and accuracy. However, the interpretability of such models remains limited, especially in terms of connecting network components to physically meaningful quantities. We propose that the attention mechanism — a central module in transformer architectures — explicitly models the conditional information flow between orbitals. Intuitively, as the transformer learns to predict orbital configurations by optimizing an energy functional, it approximates the conditional probability distribution $p(x_n|x_1,\ldots,x_{n-1})$, implicitly encoding conditional mutual information (CMI) among orbitals. This suggests a natural correspondence between attention maps and CMI structures in quantum systems. To probe this idea, we compare weighted attention scores from trained transformer wavefunction ansatze with CMI matrices across several representative small molecules. In most cases, we observe a positive rank-level correlation (Kendall's tau) between attention and CMI, suggesting that the learned attention can reflect physically relevant orbital dependencies. This study provides a quantitative link between transformer attention and conditional mutual information in the NNQS setting. Our results provide a step toward explainable deep learning in quantum chemistry, pointing to opportunities in interpreting attention as a proxy for physical correlations.

Electric-type Stern-Gerlach effect

Jiang-Lin Zhou(周蒋麟), Zou-Chen Fu(傅邹晨), Choo Hiap Oh(胡祖协), and Jing-Ling Chen(陈景灵)

Chin. Phys. B, 2026, 35 (1): 010302. DOI: 10.1088/1674-1056/ae111e

Abstract ( 25 )

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The Stern-Gerlach (SG) experiment is a fundamental experiment for revealing the existence of “spin”. In this experiment, beams of silver atoms are sent through inhomogeneous magnetic fields to observe their deflection. Thus, the conventional SG experiment can be viewed as a magnetic-type spin effect. In this work, we successfully generalize the SG effect from magnetic-type to electric-type by solving Dirac’s equation with a potential barrier, revealing an extraordinary spin effect. Beams of Dirac particles can be regarded as matter waves. Based on Dirac’s equation, we obtain the explicit forms of the incident, reflected, and transmitted waves. The electric-type SG effect shows that the reflected and transmitted waves can exhibit notable spatial shifts, which depend on the spin direction and the incident angle of the wave. The electric-type SG effect has potential applications for separating Dirac particles with different spin directions and for estimating the spin direction of Dirac particles. Some discussions related to the interaction between spin and the electric field are also presented.

Enhancing the performance of quantum battery by squeezing reservoir engineering

Yue Li(李月), Rong-Fang Liu(刘蓉芳), Jia-Bin You(游佳斌), Wan-Li Yang(杨万里), and Hua Guan(管桦)

Chin. Phys. B, 2026, 35 (1): 010303. DOI: 10.1088/1674-1056/ae1df2

Abstract ( 14 )

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Reservoir engineering has been widely used in various quantum technologies. Based on a cavity-QED (quantum electrodynamics) model, we propose a potentially practical scheme using squeezed-vacuum reservoir engineering to optimize the performance of a quantum battery (QB) located inside a cavity driven by a broadband squeezed laser, which acts as a squeezed-vacuum reservoir. Using the reduced master equation of the QB obtained via the adiabatic elimination method, we focus on the QB’s charging dynamics under tunable squeezed reservoirs governed by parametrically controlled squeezing parameters, which dictate the efficiency of energy transfer and the extractable work (ergotropy) of the QB. We show that increasing the squeezing strength improves the charging rate and enables rapid energy transfer, whereas the steady-state energy of the QB saturates at specific values of the squeezing parameter. Notably, the ergotropy of the QB reaches its maximum at a critical squeezing strength and does not scale monotonically with the squeezing strength. This nonmonotonic behavior underscores the existence of optimal parameter regimes, through which the performance of the QB can be significantly enhanced.

Efficient and controlled symmetric and asymmetric Bell-state transfers in a dissipative Jaynes-Cummings model

Qi-Cheng Wu(吴奇成), Yu-Liang Fang(方玉亮), Yan-Hui Zhou(周彦辉), Jun-Long Zhao(赵军龙), Yi-Hao Kang(康逸豪), Qi-Ping Su(苏奇平), and Chui-Ping Yang(杨垂平)

Chin. Phys. B, 2026, 35 (1): 010304. DOI: 10.1088/1674-1056/ae111f

Abstract ( 42 )

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Realizing efficient and controlled state transfers is necessary for implementing a wide range of classical and quantum information protocols. Recent studies have demonstrated that both asymmetric and symmetric state transfers can be achieved by encircling an exceptional point (EP) in non-Hermitian (NH) systems. However, the application of this phenomenon has been restricted to scenarios where an EP exists in single-qubit systems and is associated with a specific type of dissipation. In this work, we demonstrate efficient and controlled symmetric and asymmetric Bell-state transfers by modulating system parameters within a Jaynes-Cummings model while accounting for atomic spontaneous emission and cavity decay. The effective suppression of nonadiabatic transitions enables a symmetric exchange of Bell states irrespective of the encircling direction. Furthermore, we report a counterintuitive finding: the presence of an EP is not indispensable for implementing asymmetric state transfers in NH systems. We achieve perfect asymmetric Bell-state transfers even in the absence of an EP by dynamically orbiting around an approximate EP. Our work presents an approach to effectively and reliably manipulate entangled states with both symmetric and asymmetric characteristics, through dissipation engineering in NH systems.

Superadiabatic stimulated Raman adiabatic passage between dressed states

Fangzhou Jin(金芳洲), Ao Wang(王奥), Yunlan Ji(季云兰), Hui Zhou(周辉), and Jianpei Geng(耿建培)

Chin. Phys. B, 2026, 35 (1): 010305. DOI: 10.1088/1674-1056/ade1c4

Abstract ( 23 )

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Stimulated Raman adiabatic passage (STIRAP) is a widely used technique for efficient population transfer between quantum states. However, the adiabatic nature of STIRAP requires slow evolution, leading to long operation times, which limits its practical applications. The superadiabatic method has been introduced to accelerate the STIRAP process, but it often necessitates additional couplings between the initial and target states, which may not be available in the original Hamiltonian. In this work, we present a novel approach to implement superadiabatic STIRAP (sa-STIRAP) between dressed states in a three-level quantum system. By modulating the amplitude and phase of the original driving fields, the initial and target states in dressed-state space can be effectively coupled. This approach provides a practical means of realizing sa-STIRAP in experimental setups, making it convenient to accelerate adiabatic quantum state transfer.

Control of the Liouvillian gap in the finite open quantum system

Kai-Li Li(李凯丽), Yan-Sheng Liu(刘延盛), and Xi-Zheng Zhang(张禧征)

Chin. Phys. B, 2026, 35 (1): 010306. DOI: 10.1088/1674-1056/adeb60

Abstract ( 22 )

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Relaxation processes in quantum systems coupled to external environments represent one of the most fundamental nonequilibrium phenomena in condensed matter physics. The Lindblad master equation provides a powerful framework for characterizing such open quantum dynamics. In this work, we systematically investigate how different types of quantum jump operators and system geometries influence the Liouvillian gap and the properties of the nonequilibrium steady state (NESS) in finite-size systems. We demonstrate that, due to the intricate structure of the Liouvillian superoperator, multiple NESSs with unphysical characteristics can emerge. The physically meaningful steady state must instead be understood as a superposition of these NESSs that collectively satisfy the required physical constraints. Furthermore, we find that the Liouvillian gap does not necessarily increase monotonically with the system-environment coupling strength. Instead, it can exhibit a nontrivial peak structure, corresponding to a minimum in the relaxation time. The magnitude of this peak is closely related to the symmetry properties of the system. Our results provide a deeper understanding of nonequilibrium behavior in finite quantum systems and offer new insights into the design and control of open quantum dynamics.

Impact of decoherence on the metrological advantage of weak-value amplification

Yu-Han Yan(严雨涵), Yan-Ping Tan(谭艳萍), Yan-Yan Lu(陆艳艳), Shao-Jie Xiong(熊少杰), and Zhe Sun(孙哲)

Chin. Phys. B, 2026, 35 (1): 010307. DOI: 10.1088/1674-1056/ae29fe

Abstract ( 35 )

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We present a theoretical investigation of weak-value amplification (WVA) under decoherence, quantifying its metrological capabilities through the quantum Fisher information (QFI). By modeling decoherence via Kraus operators acting before and after the weak measurement interaction, we derive exact expressions for the QFI governing parameter estimation of a weak coupling strength. These analytical results reveal the fundamental limitation imposed by decoherence on the QFI achievable via WVA. From these results, the optimal post-selection state that maximizes the QFI can be derived for different noise environments. Through paradigmatic examples, including amplitude damping and depolarizing channels, we demonstrate a key distinction: the optimal post-selection evolves with the noise strength in the amplitude damping channel, but is fixed in the depolarizing channel. This work provides both theoretical insights and practical guidance for optimizing metrological schemes based on WVA in realistic decoherent environments.

An artificial synapse capable of regulating signal transmission speed in a neuromorphic network

Jingru Sun(孙晶茹), Xiaosong Li(李晓崧), Yichuang Sun(孙义闯), Zining Xiong(熊子宁), and Jiqi He(何计奇)

Chin. Phys. B, 2026, 35 (1): 010501. DOI: 10.1088/1674-1056/ae1c2c

Abstract ( 42 )

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The regulation of signal transmission speed is one of the most important capabilities of the biological nervous system. This study explores the mechanisms and methods for regulating signal transmission speed among nonmyelinated neurons within the same brain region, starting from spike-timing-dependent plasticity (STDP) of synapses. Building upon the Hodgkin-Huxley model, the dynamic behavior of synapses is incorporated, and the adaptive growth neuron (AGN) model is proposed. Artificial synaptic structures and neuronal physical nodes are also designed. The artificial synaptic structure exhibits unidirectionality, memory capacity, and STDP, enabling it to connect neuronal physical nodes through branching and merging structures. Furthermore, the artificial synapse can adjust signal transmission speed, regulate functional competition between different regions of the neuromorphic network, and promote information interaction. The findings of this study endow neuromorphic networks with the ability to regulate signal transmission speed over the long term, providing new insights into the development of neuromorphic networks.

Dynamic analysis and DNA coding-based image encryption of memristor synapse-coupled hyperchaotic IN-HNN network

Shuang Zhao(赵双), Yunzhen Zhang(张云贞), Xiangjun Chen(陈湘军), Bin Gao(高彬), and Chengjie Chen(陈成杰)

Chin. Phys. B, 2026, 35 (1): 010502. DOI: 10.1088/1674-1056/ae1dec

Abstract ( 31 )

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The rapid development of brain-like neural networks and secure data transmission technologies has placed greater demands on highly complex neural network systems and highly secure encryption methods. To this end, the paper proposes a novel high-dimensional memristor synapse-coupled hyperchaotic neural network by using the designed memristor as the synapse to connect an inertial neuron (IN) and a Hopfield neural network (HNN). By using numerical tools including bifurcation plots, phase plots, and basins of attraction, it is found that the dynamics of this system are closely related to the memristor coupling strength, self-connection synaptic weights, and inter-connection synaptic weights, and it can exhibit excellent hyperchaotic behaviors and coexisting multi-stable patterns. Through PSIM circuit simulations, the complex dynamics of the coupled IN-HNN system are verified. Furthermore, a DNA-encoded encryption algorithm is given, which utilizes generated hyperchaotic sequences to achieve encoding, operation, and decoding of DNA. The results show that this algorithm possesses strong robustness against statistical attacks, differential attacks, and noise interference, and can effectively resist known/selected plaintext attacks. This work will provide new ideas for the modeling of large-scale brain-like neural networks and high-security image encryption.

Energy adaptive regulation of a multifunctional neuron circuit

Xi-kui Hu(胡锡奎), Juan Yang(杨娟), and Ping Zhou(周平)

Chin. Phys. B, 2026, 35 (1): 010503. DOI: 10.1088/1674-1056/ae1451

Abstract ( 60 )

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This study constructs a dual-capacitor neuron circuit (connected via a memristor) integrated with a phototube and a thermistor to simulate the ability of biological neurons to simultaneously perceive light and thermal stimuli. The circuit model converts photothermal signals into electrical signals, and its dynamic behavior is described using dimensionless equations derived from Kirchhoff's laws. Based on Helmholtz's theorem, a pseudo-Hamiltonian energy function is introduced to characterize the system's energy metabolism. Furthermore, an adaptive control function is proposed to elucidate temperature-dependent firing mechanisms, in which temperature dynamics are regulated by pseudo-Hamiltonian energy. Numerical simulations using the fourth-order Runge—Kutta method, combined with bifurcation diagrams, Lyapunov exponent spectra, and phase portraits, reveal that parameters such as capacitance ratio, phototube voltage amplitude/frequency, temperature, and thermistor reference resistance significantly modulate neuronal firing patterns, inducing transitions between periodic and chaotic states. Periodic states typically exhibit higher average pseudo-Hamiltonian energy than chaotic states. Two-parameter analysis demonstrates that phototube voltage amplitude and temperature jointly govern firing modes, with chaotic behavior emerging within specific parameter ranges. Adaptive control studies show that gain/attenuation factors, energy thresholds, ceiling temperatures, and initial temperatures regulate the timing and magnitude of system temperature saturation. During both heating and cooling phases, temperature dynamics are tightly coupled with pseudo-Hamiltonian energy and neuronal firing activity. These findings validate the circuit's ability to simulate photothermal perception and adaptive temperature regulation, contributing to a deeper understanding of neuronal encoding mechanisms and multimodal sensory processing.

Dynamics analysis and DSP implementation of the Rulkov neuron model with memristive synaptic crosstalk

Yichen Bi(毕毅晨), Jun Mou(牟俊), Herbert Ho-Ching Iu, Nanrun Zhou(周南润), Santo Banerjee, and Suo Gao(高锁)

Chin. Phys. B, 2026, 35 (1): 010504. DOI: 10.1088/1674-1056/ae1728

Abstract ( 31 )

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The human brain is a complex intelligent system composed of tens of billions of neurons interconnected through synapses, and its intricate network structure has consistently attracted numerous scientists to explore the mysteries of brain functions. However, most existing studies have only verified the biological mimicry characteristics of memristors at the single neuron-synapse level, and there is still a lack of research on memristors simulating synaptic coupling between neurons in multi-neuron networks. Based on this, this paper uses discrete memristors to couple dual discrete Rulkov neurons, and adds synaptic crosstalk between the two discrete memristors to form a neuronal network. A memristor-coupled dual-neuron map, called the Rulkov-memristor-Rulkov (R-M-R) map, is constructed to simulate synaptic connections between neurons in biological tissues. Then, the equilibrium points of the R-M-R map are studied. Subsequently, the effect of parameter variations on the dynamic performance of the R-M-R map is comprehensively analyzed using bifurcation diagram, phase diagram, Lyapunov exponent spectrum (LEs), firing diagram, and spectral entropy (SE) complexity algorithms. In the R-M-R map, diverse categories of periodic, chaotic, and hyperchaotic attractors, as well as different states of firing patterns, can be observed. Additionally, different types of state transitions and coexisting attractors are discovered. Finally, the feasibility of the model in digital circuits is verified using a DSP hardware platform. In this study, the coupling principle of biological neurons is simulated, the chaotic dynamic behavior of the R-M-R map is analyzed, and a foundation is laid for deciphering the complex working mechanisms of the brain.

Synchronization of neuromorphic memristive Josephson junction network and its application

Dejun Yan(严德军), Fuqiang Wu(吴富强), and Wenshuai Wang(汪文帅)

Chin. Phys. B, 2026, 35 (1): 010505. DOI: 10.1088/1674-1056/ae1456

Abstract ( 74 )

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Neuromorphic circuits based on superconducting tunnel junctions have attracted much attention due to their high-speed computing capabilities and low energy consumption. Josephson junction circuits can effectively mimic biological neural dynamics. Leveraging these advantages, we construct a Josephson junction neuron-like model with a phase-dependent dissipative current, referred to as a memristive current. The proposed memristive Josephson junction model exhibits complex dynamical behaviors. Furthermore, considering the effect of a fast-modulated synapse, we explore synchronization phenomena in coupled networks under varying coupling conductances and excitatory/inhibitory interactions. Finally, we extend the neuromorphic Josephson junction model—exhibiting complex dynamics—to the field of image encryption. These results not only enrich the understanding of the dynamical characteristics of memristive Josephson junctions but also provide a theoretical basis and technical support for the development of new neural networks and their applications in information security technology.

Multiscale structural complexity analysis of the Chinese classics A Dream of Red Mansions and All Men Are Brothers

Jing Feng(冯靖), Ping Wang(王萍), and Changgui Gu(顾长贵)

Chin. Phys. B, 2026, 35 (1): 010506. DOI: 10.1088/1674-1056/ae1fe9

Abstract ( 40 )

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Text, as a fundamental carrier of human language and culture, exhibits high structural and semantic complexity. Its systematic analysis is essential for understanding linguistic patterns and cultural transmission. A Dream of Red Mansions and All Men Are Brothers, two masterpieces of Chinese classical literature, have long been central to debates regarding the authorship of their later chapters. Previous studies, often based on word-frequency statistics, function word distributions, entropy measures, and complex network analyses, have provided valuable insights into stylistic differences; however, they remain limited in capturing cross-scale structural features. To address this gap, we apply a multi-scale structural complexity approach based on character-frequency time series to analyze the structural evolution of both novels under various segmentation strategies. Our results reveal significant differences in peak complexity positions, overall complexity levels, and intra-textual variations between the two works, which are closely linked to changes in authorship and stylistic patterns. This study not only provides new quantitative evidence for resolving authorship disputes in classical literature but also demonstrates, from the perspective of structural complexity, the profound depth and unique charm of Chinese literary expression, highlighting the richness of Chinese language and culture. Moreover, it emphasizes the potential of structural complexity analysis as a versatile tool for textual analysis and style attribution.

Dynamic balance and reliability of a stochastic ecosystem with Markov switching

Ya-Nan Sun(孙雅楠), Xin-Zhi Liu(刘新芝), and You-Ming Lei(雷佑铭)

Chin. Phys. B, 2026, 35 (1): 010507. DOI: 10.1088/1674-1056/adea58

Abstract ( 24 )

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A stochastic predator-prey system with Markov switching is explored. We have developed a new chasing technique to efficiently solve the Fokker-Planck-Kolmogorov and backward Kolmogorov equations. Dynamic balance and reliability of the switching system are evaluated via stationary probability density function and first-passage failure theory, taking into account factors such as switching frequencies, noise intensities, and initial conditions. Results reveal that Markov switching leads to stochastic P-bifurcation, enhancing dynamic balance and reducing white-noise-induced oscillations. But frequent switching can heighten initial value dependence, harming reliability. Further, the influence of the subsystem on the switching system is not proportional to its action probabilities. Monte Carlo simulations validate the findings, offering an in-depth exploration of these dynamics.

Enhancing thermodynamic performances and suppressing fluctuations in interacting quantum-dot thermoelectric engines

Jianhan Zhuang(庄剑涵), Qinyan Zou(邹沁研), Ziming Wang(王子明), Gaoyuan Chen(陈高远), Jian Sun(孙坚), Xiang Hao(郝翔), Chen Wang(王晨), and Jincheng Lu(陆金成)

Chin. Phys. B, 2026, 35 (1): 010508. DOI: 10.1088/1674-1056/ae12de

Abstract ( 12 )

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Quantum dot systems emerge as promising platforms for studying nanoscale thermoelectric effects and quantum fluctuation phenomena. In this work, we investigate the thermodynamic performance of a Coulomb-blockaded quantum dot operating as a quantum heat engine using the quantum master equation approach. By incorporating full counting statistics, we analyze both average transport properties and current fluctuations in this nanoscale system. We demonstrate that electron-electron interactions significantly enhance thermoelectric performance by increasing both the output power and energy conversion efficiency. Furthermore, we show that Coulomb interactions suppress current fluctuations while preserving the validity of the thermodynamic uncertainty relation. Our results provide important insights into the interplay between quantum effects and thermodynamic principles in nanoscale heat engines.

Phasemeter based on second harmonic signal filter for space-based gravitational wave detection

Zheng Fan(范正), Zhu Li(李祝), Xiangqing Huang(黄祥青), Yurong Liang(梁浴榕), Yu Song(宋煜), Maomao Fan(范毛毛), Huizong Duan(段会宗), Siyuan Peng(彭思远), Shanqing Yang(杨山清), and Liangcheng Tu(涂良成)

Chin. Phys. B, 2026, 35 (1): 010601. DOI: 10.1088/1674-1056/ae1efe

Abstract ( 20 )

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The space gravitational wave detection aims to detect gravitational waves in the mHz band in order to study supermassive black hole mergers, galaxy evolution and the structure of the early universe. One of its core payloads is a transponder-type interstellar laser interferometer, designed to measure relative displacement changes at the pico-meter level. Among its components, phasemeter is tasked with extracting the phase and frequency of the interference signal. Currently, phase-locked loop (PLL) phasemeters are commonly employed. However, the second harmonic signal generated by the mixer can restrict both the dynamic range and phase measurement accuracy of the phasemeter. This paper analyzes the interstellar laser interferometer and the impact of the second harmonic signal on the phasemeter’s performance. To address these challenges, a phasemeter incorporating a second harmonic signal filter is proposed. This new design mitigates second harmonic disturbances within the phasemeter’s bandwidth by dynamically adjusting the filter’s cutoff frequency to track the input signal frequency, thereby suppressing the second harmonic signal in real time. Theoretical and simulation analyses demonstrate that the proposed phasemeter with a second harmonic filter significantly enhances the dynamic range. Finally, experimental results verify that the phasemeter can achieve the tracking of sudden frequency changes up to 4.8 MHz.

Enhanced timing of a 113 km O-TWTFT link with complex maximum likelihood estimation process

Yu-Chen Fang(方宇辰), Jian-Yu Guan(管建宇), Qi Shen(沈奇), Jin-Jian Han(韩金剑), Lei Hou(侯磊), Meng-Zhe Lian(连蒙浙), Yong Wang(王勇), Wei-Yue Liu(刘蔚悦), Ji-Gang Ren(任继刚), Cheng-Zhi Peng(彭承志), Qiang Zhang(张强), Hai-Feng Jiang(姜海峰), and Jian-Wei Pan(潘建伟)

Chin. Phys. B, 2026, 35 (1): 010602. DOI: 10.1088/1674-1056/ae1120

Abstract ( 21 )

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Optical two-way time-frequency transfer (O-TWTFT), utilizing optical frequency comb carriers and linear optical sampling, effectively enables space-to-ground optical frequency standard comparisons. Previously reported detection sensitivities of O-TWTFTs were typically in the nanoWatt level, necessitating high-power optical frequency combs to compensate for significant losses in high-orbit satellite-to-ground passes. Such hardware-based solutions, while effective, tend to be costly. This paper presents a novel data post-processing algorithm to enhance sensitivity. Unlike previous timing methods, which depend solely on optical phase data and discard intensity information — resulting in elevated errors, especially under low-reception power, our approach employs complex least squares (CLS) estimation in the complex frequency domain. By preserving all intermediate data and avoiding noise from phase unwrapping, it achieves superior sensitivity and accuracy. Experiments over a 113-kilometer free-space link validate the algorithm’s robustness, delivering a detection sensitivity of 0.1 nanoWatts — over tenfold better than prior techniques — despite a 100-decibel link loss, comparable to Earth-Moon optical links.

Multiparameter hierarchical sensitivity analysis of tilt-to-length coupling noise in Taiji science interferometer

Fei Xie(谢菲), Xiaodong Peng(彭晓东), Wenlin Tang(唐文林), Mengyuan Zhao(赵梦圆), and Xiaoshan Ma(马晓珊)

Chin. Phys. B, 2026, 35 (1): 010701. DOI: 10.1088/1674-1056/ae07a8

Abstract ( 12 )

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Tilt-to-length (TTL) coupling noise is a critical issue in space-based gravitational wave detection due to its complex dependence on multiple interacting factors, which complicates the identification of dominant parameters. To address this challenge, we develop a simulation model of the Taiji scientific interferometer, generating noise datasets under multi-parameter conditions. Given the uniqueness of the telescope as well as the convergence behavior of the algorithm, the analysis is structured hierarchically: (i) the telescope level and (ii) the optical bench level. A hierarchical framework combining XGBoost and SHapley Additive exPlanations (SHAP) values is employed to model the intricate relationships between parameters and TTL coupling noise, supplemented by sensitivity analysis. Our results identify pointing jitter and telescope radius as the dominant parameters at the telescope level, while the angles of the plane mirrors and beam splitters are most influential at the optical bench level. The parameter space is reduced from 86 dimensions to 14 dimensions without sacrificing model accuracy. This approach offers actionable insights for optimizing the Taiji interferometer design.

Structures and dynamics of helium in liquid lithium: A study by deep potential molecular dynamics

Xinyu Zhu(朱新宇), Jianchuan Liu(刘建川), Tao Chen(陈涛), Xinyue Xie(谢炘玥), Jin Wang(王进), Yi Xie(谢懿), Chenxu Wang(王晨旭), and Mohan Chen(陈默涵)

Chin. Phys. B, 2026, 35 (1): 013101. DOI: 10.1088/1674-1056/ae15f1

Abstract ( 28 )

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Current experimental techniques still face challenges in clarifying the structural and dynamic properties of helium (He) in liquid lithium (Li). A critical example of this technical hurdle is the formation of He bubbles, which significantly affects the transport of He within liquid Li — a vital aspect when considering liquid Li as a plasma-facing material in nuclear fusion reactors. We develop a machine-learning-based deep potential (DP) with ab initio accuracy for the Li—He system and perform molecular dynamics simulations at temperatures ranging from 470 K to 1270 K with a wide range of He concentrations. We observe that He atoms exhibit a tendency to aggregate and form clusters and bubbles in liquid Li. Notably, He clusters exhibit a significant increase in size at elevated temperatures and high concentrations of He, accompanied by the phase separation of Li and He atoms. We also observe an anomalous non-linear relationship between the diffusion coefficient of He and temperature, which is attributed to the larger cluster size at higher temperatures. Our study provides a deeper understanding of the behavior of He in liquid Li and further supports the potential application of liquid Li under extreme conditions.

Theoretical study on low-lying excited states of B₃ molecule

Mu-Hong Hu(胡木宏), Zhi-Xue Zhao(赵志学), Xin-Yi Li(李馨怡), Li-Dan Xiao(肖利丹), and Bing Yan(闫冰)

Chin. Phys. B, 2026, 35 (1): 013102. DOI: 10.1088/1674-1056/adf31d

Abstract ( 12 )

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The electronic states of the smallest boron cluster B$_{3}$ with excitation energies up to 5 eV are systematically investigated. Geometries and spectroscopic constants for the low-lying electronic states were calculated using the multireference configuration interaction method with Davidson correction (MRCI$+$Q). The nondegenerate 1$\,{}^{2}$B$_{2}$ and 2$\,{}^{2}$A$_{1}$ states are arising from the degenerate $\,{}^{2}$E$'$ state in $D_{3h}$ symmetry, this is also the case for 2$\,{}^{2}$B$_{2}$ and 3$\,{}^{2}$A$_{1}$. Furthermore, vertical excitation energies, oscillator strengths, main configurations, and transitions of the excited state of B$_{3}$ were determined. Notably, the theoretically predicted wavelengths for the X$\,{}^{2}$A$_{1}\to\; $2$\,{}^{2}$A$_{1}$ and X$\,{}^{2}$A$_{1} {} \to\; $2$\,{}^{2}$B$_{2}$ electronic transitions (728 nm and 457 nm, respectively) exhibit excellent agreements with experimental absorption bands observed at 736 nm and 458 nm. These theoretical findings provide critical insights into the electronic structure and geometric configuration of the B$_{3}$ cluster.

New spectroscopic data on even-parity autoionization states for two-color two-step photoionization of nickel atom

Jun-Yao Zhang(张钧尧), Jing-Yi Xiong(熊静逸), Hong-Ru Zhou(周鸿儒), Cai-Hua Zhu(朱才华), Huai-Miao Sun(孙槐苗), Li-De Wang(王立德), Kai-Chen Ma(马恺宸), Jun-Jie Chai(柴俊杰), and Yun-Fei Li(李云飞)

Chin. Phys. B, 2026, 35 (1): 013201. DOI: 10.1088/1674-1056/adf4ae

Abstract ( 20 )

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The development of collinear resonance ionization spectroscopy for studying the nuclear structure of nickel isotopes far from the stability line relies on high-efficiency two-color two-step photoionization pathways. We systematically investigated the even-parity autoionization spectrum of atomic nickel through resonance ionization mass spectrometry (RIMS). Fifteen intense single-color photoionization lines and corresponding transitions in the 300-325 nm range were identified and excluded as potential interference peaks for subsequent two-color studies. Fifty-one even-parity autoionization states in the 64000-66800 cm$^{-1}$ range were identified for the first time by scanning from five intermediate excited states of the 3d$^{8}$(${}^{3}$F)4s4p(${}^{3}$P$^{\rm o}$) configuration. Forty-eight of these states were assigned unique total angular momentum quantum numbers ($J$) based on electric dipole transition selection rules. The autoionization state at 64437.77 cm$^{-1}$ was identified as an optimal final state for enhancing photoionization efficiency in two-color two-step pathways. This study provides comprehensive datasets of even-parity autoionization states of nickel, supporting both the advancement of collinear resonance ionization spectroscopy for exotic nickel isotopes and theoretical modeling of autoionization states. The datasets are openly available at https://doi.org/10.57760/sciencedb.j00113.00280.

Co-optimization of linear gain and dynamic range for atomic superheterodyne receivers based on homodyne readout

Chuan Qu(瞿川), Dongqin Guo(郭东琴), and Jian Zhang(张剑)

Chin. Phys. B, 2026, 35 (1): 013202. DOI: 10.1088/1674-1056/ade8e9

Abstract ( 8 )

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Rydberg-atom-based superheterodyne receivers integrate self-calibration, high sensitivity, a wide operational frequency range, and phase/frequency resolved detection capabilities, demonstrating broad application prospects as next-generation microwave receivers. Linear gain and linear dynamic range (LDR) are critical metrics for assessing receiver sensitivity and demodulation fidelity, respectively. We numerically solve the four-level master equation and then employ particle swarm optimization (PSO) algorithm to co-optimize linear gain and LDR in atomic superheterodyne receivers based on balanced homodyne detection. Further, we systematically account for dominant dephasing mechanisms in the simulation, encompassing spontaneous decay, transit dephasing, collision dephasing, laser linewidth dephasing, and Doppler averaging. Homodyne readout utilizes both the real and imaginary parts of polarizability for sensing. In the case of the photon shot noise limit, its signal-to-noise ratio (SNR) expression resembles that of direct optical-intensity readout. However, the inherent coherent subtraction operation in homodyne detection significantly suppresses common-mode noise, while appropriately increasing the reference beam power enhances the gain in practical experiments. Indeed, this co-optimization problem, characterized by a high-dimensional variable space, two objectives, and non-convexity, is well-suited for solution by PSO. In addition, probe and coupling detuning contribute equivalently to polarizability and compensate for each other owing to Doppler averaging, thereby reducing the optimization variable space by one. By adopting a product form of linear gain and LDR as the fitness function, the PSO achieves rapid convergence. Here, the effectiveness of the PSO results is verified via the total harmonic distortion (THD). The relative error-based LDR calculation method we proposed efficiently measures receiver response linearity with consuming fewer computational resources. This research is expected to offer valuable insights into enhancing the performance of Rydberg-atom-based superheterodyne receivers.

Single electron capture in low- and intermediate-energy collisions of Si^3,4+ with He

Yingzhou Li(李英卓), Yadong Liu(刘亚东), Yueying Qi(祁月盈), Ling Liu(刘玲), Yizhi Qu(屈一至), and Jianguo Wang(王建国)

Chin. Phys. B, 2026, 35 (1): 013401. DOI: 10.1088/1674-1056/ae15f4

Abstract ( 19 )

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The single electron capture processes in Si$^{3,4+}+$He collisions have been investigated theoretically employing the two-center atomic orbital close-coupling method in the energy range 0.01-100 keV/u. Total and state-selective electron capture cross sections for the dominant and subdominant reaction channels are calculated and compared with the available experimental and theoretical data. For the total charge transfer cross sections, the present results show better agreements with the available experimental data than the other theoretical ones in the overlapping energy region for both collision systems. For the state-selective cross sections, the present results for 3s and 3p states are in general agreement with the previous MOCC results in the low energy region for both collision systems. Furthermore, the cross sections for electron captured to the 3d, 4$l$ and 5$l$ ($l=0$, 1, ..., $n-1$) states of Si$^{2+}$ and Si$^{3+}$ ions are first provided in a broad energy region in our work. These results are useful for the investigations in astrophysics. The datasets presented in this paper, including the total and state-selective electron capture cross sections of Si$^{3,4+}+$He collisions in 0.01-100 keV/u, are openly available at https://doi.org/10.57760/sciencedb.j00113.00257.

Compact dual MOT apparatus of K and Rb for optical tweezer experiment

Kedi Wei(魏可迪), Yangbo Wei(韦样波), Shangjin Li(李上进), and Bo Yan(颜波)

Chin. Phys. B, 2026, 35 (1): 013701. DOI: 10.1088/1674-1056/ade8e2

Abstract ( 4 )

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The optical tweezer experiment with neutral atoms is widely used for quantum information research. Here, we present a compact dual magneto-optical trap (MOT) setup for a two-species optical tweezer. Rubidium (Rb) atoms are directly captured using a vapor MOT, while potassium (K) atoms are collected via a 2-stage MOT. Both the quadratic and gradient magnetic fields required for the MOT and Zeeman slower are created by permanent magnets. With the help of the Zeeman slower, the K MOT loading efficiency is enhanced by a factor of three. After the MOT stage, we apply D$_1$ gray molasses to reduce the temperature of the K atoms to 9 μK. Using this apparatus, both Rb and K are loaded into the optical tweezer.

Highly sensitive, multi-stage, and mid-infrared refractive index sensor based on photonic spin Hall effect

Jiaye Ding(丁嘉烨), Chenglong Wang(汪承龙), Shengli Liu(刘胜利), Peng Dong(董鹏), and Jie Cheng(程杰)

Chin. Phys. B, 2026, 35 (1): 014201. DOI: 10.1088/1674-1056/ade24c

Abstract ( 24 )

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Surface polaritons, as surface electromagnetic waves propagating along the surface of a medium, have played a crucial role in enhancing photonic spin Hall effect (PSHE) and developing highly sensitive refractive index (RI) sensors. Among them, the traditional surface plasmon polariton (SPP) based on noble metals limits its application beyond the near-infrared (IR) regime due to the large negative permittivity and optical losses. In this contribution, we theoretically proposed a highly sensitive PSHE sensor with the structure of Ge prism-SiC-Si:InAs-sensing medium, by taking advantage of the hybrid surface plasmon phonon polariton (SPPhP) in mid-IR regime. Here, heavily Si-doped InAs (Si:InAs) and SiC excite the SPP and surface phonon polariton (SPhP), and the hybrid SPPhP is realized in this system. More importantly, the designed PSHE sensor based on this SPPhP mechanism achieves the multi-stage RI measurements from 1.00025-1.00225 to 1.70025-1.70225, and the maximal intensity sensitivity and angle sensitivity can be up to 9.4$\times10^{4}$μm/RIU and 245 $^\circ$/RIU, respectively. These findings provide a new pathway for the enhancement of PSHE in mid-IR regime, and offer new opportunities to develop highly sensitive RI sensors in multi-scenario applications, such as harmful gas monitoring and biosensing.

Image-free single-pixel semantic segmentation for complex scene based on multi-scale U-Net

Tengfei Liu(刘腾飞), Yanfeng Bai(白艳锋), Jianxia Chen(陈健霞), Jintao Zhai(翟锦涛), Siqing Xiang(向思卿), Xianwei Huang(黄贤伟), and Xiquan Fu(傅喜泉)

Chin. Phys. B, 2026, 35 (1): 014202. DOI: 10.1088/1674-1056/ade4b0

Abstract ( 20 )

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Single-pixel imaging (SPI) receives widespread attention due to its superior anti-interference capabilities, and image segmentation technology can effectively facilitate its recognition and information extraction. However, the complexity of the target scene and plenty of imaging time in SPI make it challenging to achieve high-quality and concise segmentation. In this paper, we investigate the image-free intricate scene semantic segmentation in SPI. Using "learned" illumination patterns allows for the full extraction of the object's spatial information, thereby enabling pixel-level segmentation results through the decoding of the received measurements. Simulation and experimentation show that, in the absence of image reconstruction, the mean intersection over union (MIoU) of segmented image can reach higher than 85%, and the Dice coefficient (DICE) close to 90% even at the sampling ratio of 5%. Our approach may be favorable to applications in medical image segmentation and autonomous driving field.

Evolution of angular-resolved rate of Thomson scattering in intense laser fields

Ying Shen(申颖), Xianghe Ren(任向河), and Jingtao Zhang(张敬涛)

Chin. Phys. B, 2026, 35 (1): 014203. DOI: 10.1088/1674-1056/ade1bf

Abstract ( 23 )

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By employing a full quantum theory of electron-photon scattering in intense laser fields, we calculate the angular-resolved radiation rate of the fundamental wave in Thomson scattering. We investigate the dependence of radiation rate on Euler angles and elucidate the underlying physical mechanism. The figure-8 profile of the radiation rate within the polarization plane is validated, while its evolution with respect to laser intensity and electron momentum is illustrated. Our findings reveal that in lower-intensity laser fields and for slow electron motion, the angular-resolved radiation rate exhibits distinct dipole emission characteristics. However, significant changes are observed at high laser intensities and/or large electron momenta, leading to pronounced alterations in the angular-resolved radiation rate. Remarkably similar variation patterns can be achieved by proportionally adjusting both laser intensity and electron momentum.

Effect of measurement reduction on synthetic aperture x-ray ghost imaging

Haipeng Zhang(张海鹏), Jie Tang(汤杰), Nixi Zhao(赵尼西), Changzhe Zhao(赵昌哲), Jianwen Wu(吴建文), Zhongliang Li(李中亮), and Tiqiao Xiao(肖体乔)

Chin. Phys. B, 2026, 35 (1): 014204. DOI: 10.1088/1674-1056/ae07ab

Abstract ( 20 )

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The unique advantage of x-ray ghost imaging (XGI) is its potential in low dose radiology. One of the practical ways to reduce the radiation exposure is to reduce the measurements while remaining sufficient image quality. Synthetic aperture x-ray ghost imaging (SAXGI) is invented to achieve megapixel XGI with limited measurements, which is expected to implement XGI simultaneously with large field of view and low radiation exposure. In this paper, we experimentally investigate the effect of measurements reduction on the spatial resolution and image quality of SAXGI with standard sample and biomedical specimen. The results with a resolution chart demonstrated that at 360 measurements, SAXGI successfully retrieved the sample image of 1960×1960 pixels with spatial resolution of 4 μm. With measurement reduction, the spatial resolution deteriorates but the sparser structures are still discernable. Even with measurements reduced to 10, a spatial resolution of 10 μm can still be achieved by SAXGI. A biomedical sample of a fish specimen is employed to evaluate the method and the fish image of 2000×1000 pixels with an SSIM of 0.962 is reconstructed by SAXGI with 770 measurements, corresponding to an accumulative exposure reduction of more than 2 times. With the measurements reduced to 10 which corresponds to 1/160 of the accumulative radiation exposure for conventional radiology, bulky structure like the fish skeleton can still be definitely discerned and the SSIM for the reconstructed image still retained 0.9179. Results of this paper demonstrate that measurements reduction is practicable for the radiation exposure reduction of the sample, which implicates that SAXGI with limited measurements is an efficient solution for low dose radiology.

Phase sensitivity of a lossy truncated SU(1,1) interferometer with double-port homodyne detection

Yu-Wei Xiao(肖煜伟), Yue Ji(吉悦), Jia-Yi Wei(魏嘉怡), Jian-Dong Zhang(张建东), and Li-Li Hou(侯丽丽)

Chin. Phys. B, 2026, 35 (1): 014205. DOI: 10.1088/1674-1056/adfd46

Abstract ( 43 )

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We theoretically investigate the phase sensitivity of a truncated SU(1,1) interferometer fed with a two-mode coherent state and employing double-port homodyne detection. On the one hand, we analytically demonstrate that the two-mode coherent state provides better phase sensitivity than the single-mode coherent state. In addition, we show that the double-port homodyne detection is a quasi-optimal measurement. For a bright coherent-state input, the sensitivity of this scheme saturates the phase-sensitivity bound determined by the quantum Fisher information. On the other hand, we quantitatively illustrate the advantage of double-port homodyne detection over the single-port scheme under ideal conditions and in the presence of photon loss, respectively. Furthermore, our analysis indicates that the scheme we propose is robust against photon loss.

Generation of ultra-flat broad spectrum with stable single-pulse mode-locking in double-clad Yb-doped fiber laser

Minghui Sun(孙铭烩), Dongxin Gao(高懂昕), Yunli Yu(于芸丽), Wenyu Wang(王文煜), Qingcao Liu(刘情操), Weixin Liu(刘维新), and Yuzhai Pan(潘玉寨)

Chin. Phys. B, 2026, 35 (1): 014206. DOI: 10.1088/1674-1056/adea59

Abstract ( 31 )

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We achieved an ultra-flat broad spectrum output with a 20-dB bandwidth of 77.85 nm in a double-clad Yb-doped fiber laser. The intensity difference between the highest and lowest points of the spectrum indicates a flatness better than 4 dB. More notably, this ultra-flat broad spectrum maintains a stable single-pulse mode-locking state. With the increase of pump power, an ultra-wide spectrum with a 20-dB bandwidth approaching 100 nm was formed at a pump power of 2.25 W. Additionally, we obtained a 9-pulse mode-locked state at another PC station with the same pump, which is the highest number of stable mode-locked pulse bursts observed so far with a first-order Raman frequency shift. This fiber laser shows its benefits of ultra-flat broad spectrum, high stability, and ease of fabrication, which provides a new method of obtaining the broadband light source for multiple practical applications.

Atomic ensemble-assisted ground-state cooling of a rotating mirror in a triple Laguerre–Gaussian cavity

Xiaoxuan Li(李晓璇), Junfei Chen(陈骏飞), and Qingxia Mu(穆青霞)

Chin. Phys. B, 2026, 35 (1): 014207. DOI: 10.1088/1674-1056/ade386

Abstract ( 35 )

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We propose a novel cooling protocol within a triple-Laguerre-Gaussian cavity optomechanical system, which is designed to suppress the thermal vibrations of a rotating mirror to reach its quantum ground state. The system incorporates two auxiliary cavities and an atomic ensemble coupled to a Laguerre-Gaussian rotational cavity. By carefully selecting system parameters, the cooling process of the rotating mirror is significantly enhanced, while the heating process is effectively suppressed, enabling efficient ground-state cooling even in the unresolved sideband regime. Compared to previous works, our scheme reduces the stringent restrictions on auxiliary systems, making it more experimentally feasible under broader parameter conditions. These findings provide a robust approach for achieving ground-state cooling in mechanical resonators.

Chaotic dynamics of Pr³⁺/Yb³⁺-doped all-fiber up-conversion visible fiber laser

Yisong Li(李义松), Yueling Hao(郝悦伶), Juanfen Wang(王娟芬), Xiaohui Chen(陈晓晖), Shengxiang Chen(陈胜祥), Chao Zhou(周超), Lingzhen Yang(杨玲珍)

Chin. Phys. B, 2026, 35 (1): 014208. DOI: 10.1088/1674-1056/ade4b5

Abstract ( 34 )

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We investigate theoretically and experimentally the chaotic dynamics of visible-wavelength all-fiber ring laser. The 100-m 630 HP fibers are used to ensure high non-linearity. A 4-m Pr$^{3+}$/Yb$^{3+}$-co-doped ZBLAN fiber provides the gain. The chaotic laser was pumped by the laser diodes with the maximum power of 150 mW at the wavelength of 850 nm. The peak fluorescence spectrum of Pr$^{3+}$/Yb$^{3+}$-co-doped ZBLAN fiber at the wavelength of 635 nm shows that the visible-wavelength fiber laser can be achieved by synergistic energy transfer between Pr$^{3+}$ and Yb$^{3+}$ ions. The chaotic fiber laser is generated by adjusting the pump power, polarization controller and the auto-correlation, permutation entropy, skewness, and kurtosis were used to analyze the characteristics of chaotic laser. The noise-like time series and delta-like auto-correlation curve indicate the chaotic output. The complexity and randomness of time series are analyzed by the permutation entropy, skewness, and kurtosis. The result shows that chaotic dynamics is stable when the pump power exceeds a certain value. The visible chaotic all-fiber laser has high stability and can be applied for real-time monitoring and sensing. We believe that this approach may also be feasible for other materials for emission in the visible range.

Transmission property of one-dimensional Dirac-semimetal-defected photonic crystal in terahertz multi-bandgap

Ji-Kai Wang(王济凯), Li Jiang(姜丽), Xue-Fei Yang(杨雪菲), and Ji-He Zhao(赵继和)

Chin. Phys. B, 2026, 35 (1): 014209. DOI: 10.1088/1674-1056/ade4b3

Abstract ( 32 )

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A symmetrical one-dimensional (1D) photonic crystal structure with a Dirac-emimetal-defected layer is proposed. The material properties of the Dirac semimetal are governed by three key parameters: Fermi level, Fermi velocity, and degeneracy factor. Simulation results demonstrate that the proposed structure generates multiple photonic bandgaps within the THz frequency range. In the low-THz region, pronounced resonant transmission peaks emerge, enabling near-perfect filtering performance. The positions of these defect modes can be dynamically tuned by adjusting the Fermi level and degeneracy factor. In mid- and high-THz frequency bands, the Dirac semimetal begins to exhibit metallic behavior, leading to attenuation of the transmission peaks and the appearance of absorption. The elevation of the Fermi level delays the critical threshold for the transition from the dielectric state to the metallic state, while an increase in Fermi velocity suppresses metallic behavior. Therefore, enhancing both the Fermi level and Fermi velocity contributes to strengthening the defect peak intensity. Conversely, increasing the degeneracy factor strengthens the metallic characteristics, thereby disrupting the high-frequency photonic bandgap. Notably, the defect layer thickness and incident angle exert significant influence on the transmission behavior: a larger incident angle causes the defect peak to shift toward higher frequencies and reduces its intensity, whereas a thicker defect layer shifts the defect peak toward lower frequencies. The modulation effects of both parameters become more pronounced as frequency increases. Compared with conventional photonic crystals, our work can provide a tunable structure over transmission properties, offering novel strategies for designing tunable filters and optical sensors.

A 6-17 μm tunable and high-pulse-energy far-infrared laser based on a BaGa₄Se₇ optical parametric oscillator

Kejun Wang(王柯君), Hui Kong(孔辉), Xiaoxia Li(李晓霞), Dongbo Lv(吕东博), and Peng Xie(谢鹏)

Chin. Phys. B, 2026, 35 (1): 014210. DOI: 10.1088/1674-1056/adf82d

Abstract ( 36 )

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Tunable mid-infrared and far-infrared laser output was demonstrated based on BaGa₄Se₇ crystals and an optical parametric oscillator (OPO). With a 1.06 μm Nd:YAG laser and a double-pass singly resonant OPO cavity, a laser energy output of 2.2 mJ at 10 μm was obtained. By tuning the angle and temperature, a tunable laser output covering the wavelength range from 6 μm to 17 μm was obtained with a tuning precision better than 3 nm. The corresponding optical-to-optical conversion efficiency was 2.8%, and the slope efficiency was 4.4%. The damage effect of the output laser on detectors was also investigated, and point damage to the detector occurred at an output energy of 16.4 μJ. The laser system has the advantages of miniaturization, a wide tuning range, high energy and high tuning resolution. Its broadband laser characteristics make it highly valuable for applications in atmospheric detection, infrared spectroscopy and electro-optical countermeasures.

Ultra-broadband acoustic logic gate based on passive phase manipulation

Yu-Han Xia(夏宇涵), Nai-Qi Pang(庞乃琦), Yin Wang(王垠), Long-Xu Wang(王龙旭), and Yong Ge(葛勇)

Chin. Phys. B, 2026, 35 (1): 014301. DOI: 10.1088/1674-1056/ade667

Abstract ( 22 )

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In recent years, acoustic logic gates has attracted growing interest in acoustics due to their promising applications in acoustic communication and signal processing. For practical implementation, these logic gates must operate over a certain bandwidth to ensure reliable performance. However, current experimental realizations have predominantly been confined to single-frequency or narrowband operation, leaving their broadband capabilities largely unverified. To address this gap, we present both numerical and experimental demonstrations of three basic acoustic logic gates (OR, NOT, and AND) using a phased unit cell composed of a central channel flanked by two arrays of semicircular cavities. By leveraging phase modulation of the unit cells and linear interference of sound, we achieve these logic operations with a uniform threshold of $I_{\rm t}=0$.25. Remarkably, the measured fractional bandwidths (bandwidth relative to center frequency) reach approximately 111.5% (OR), 37.2% (NOT), and 48.5% (AND), demonstrating ultra-broadband functionality. The proposed logic gates combine exceptional bandwidth with structural simplicity, offering significant potential for applications in acoustic computing, information processing, and integrated acoustic systems.

Bio-convective flow of gyrotactic microorganisms in nanofluid through a curved oscillatory channel with Cattaneo–Christov double diffusion theory

Imran M, Naveed M, Rafiq M Y, and Abbas Z

Chin. Phys. B, 2026, 35 (1): 014401. DOI: 10.1088/1674-1056/ade066

Abstract ( 13 )

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The present study investigates the flow, heat, and mass transfer analysis in the bioconvection of nanofluid containing motile gyrotactic microorganisms through a semi-porous curved oscillatory channel with a magnetic field. These microorganisms produce density gradients by swimming, which induces macroscopic convection flows in the fluid. This procedure improves the mass and heat transfer, illustrating the interaction between biological activity and fluid dynamics. Furthermore, instead of considering traditional Fourier's and Fick's law the energy and concentration equations are developed by incorporating Cattaneo-Christov double diffusion theory. Moreover, to examine the influence of thermophoresis and Brownian diffusions in the fluid we have adopted the Buongiorno nanofluid model. Due to the oscillation of the surface of the channel, the mathematical development of the considered flow problem is obtained in the form of partial differential equations via the curvilinear coordinate system. The convergent series solution of the governing flow equations is obtained after applying the homotopy analysis method (HAM). The effects of different pertinent flow parameters on velocity, motile microorganism density distribution, concentration, pressure, temperature, and skin friction coefficient are examined and discussed in detail with the help of graphs and tables. It is observed during the current study that the density of microorganisms is enhanced for higher values of Reynolds number, Peclet number, radius of curvature variable, and Lewis number.

Steady-state fretting response governed by periodic stress variations induced by oblique excitation

Shenghao Lu(卢晟昊), Huan Wang(王欢), and Shaoze Yan(阎绍泽)

Chin. Phys. B, 2026, 35 (1): 014601. DOI: 10.1088/1674-1056/ae181b

Abstract ( 35 )

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This study investigates the mechanisms of friction-induced vibration under periodic variations in stress distribution using an improved fretting friction model. A fretting friction test system integrated with a total reflection method was developed to analyze interfacial contact behavior under dynamic loading conditions. An improved fretting friction model was established, incorporating three critical nonlinear parameters: the hysteretic friction coefficient, tangential stiffness fluctuations, and stress distribution. Through systematic validation, the model demonstrates high-fidelity replication of experimental steady-state amplitude—frequency responses. Key findings reveal that non-uniform stress distribution governs irregularities in the vibration response, and increased uniformity intensifies stick—slip instabilities. Near the stick—slip transition threshold, distinct vibration anomalies emerge due to the coupled effects of stress heterogeneity, friction hysteresis, and stiffness variations during state transitions. Furthermore, the magnitude of the normal contact force systematically alters the dominant interfacial contact mechanism. The different interfacial contact states at various frequencies lead to distinct steady-state responses. This shift elevates resonance frequencies and amplifies higher-order resonant peaks. The fretting friction model provides a predictive framework for vibration control under dynamic interfacial loading.

Predicting the synthesizability of inorganic crystals by bridging crystal graphs and phonon dynamics

Mei Ma(马梅), Wei Ma(马薇), Le Gao(高乐), Zong-Guo Wang(王宗国), and Hao Liu(刘昊)

Chin. Phys. B, 2026, 35 (1): 016101. DOI: 10.1088/1674-1056/ae0161

Abstract ( 15 )

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Accurately predicting the synthesizability of inorganic crystal materials serves as a pivotal tool for the efficient screening of viable candidates, substantially reducing the costs associated with extensive experimental trial-and-error processes. However, existing methods, limited by static structural descriptors such as chemical composition and lattice parameters, fail to account for atomic vibrations, which may introduce spurious correlations and undermine predictive reliability. Here, we propose a deep learning model termed integrating graph and dynamical stability (IGDS) for predicting the synthesizability of inorganic crystals. IGDS employs graph representation learning to construct crystal graphs that precisely capture the static structures of crystals and integrates phonon spectral features extracted from pre-trained machine learning interatomic potentials to represent their dynamic properties. Our model exhibits outstanding performance in predicting the synthesizability of low-energy unsynthesizable crystals across 41 material systems, achieving precision and recall values of 0.916/0.863 for ternary compounds. By capturing both static structural descriptors and dynamic features, IGDS provides a physics-informed method for predicting the synthesizability of inorganic crystals. This approach bridges the gap between theoretical design concepts and their practical implementation, thereby streamlining the development cycle of new materials and enhancing overall research efficiency

First-principles insights into strain-mediated He migration and irradiation resistance in W-Ta-Cr-V complex alloys

Mengdie Wang(王梦蝶), Chao Zhang(张超), Xinyue Lan(兰新月), Biao Hu(胡标), and Xuebang Wu(吴学邦)

Chin. Phys. B, 2026, 35 (1): 016102. DOI: 10.1088/1674-1056/ae29fb

Abstract ( 30 )

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High-performance intelligent protective materials are vital for nuclear energy systems exposed to extreme irradiation. Among them, tungsten-based alloys demonstrate exceptional potential owing to their superior irradiation resistance. Recent experimental studies have demonstrated that W-TaCr-V alloys exhibit excellent irradiation resistance under helium (He) ion irradiation. However, the underlying mechanisms, especially the migration behavior of He atoms, remain unclear. In this work, the influences of uniaxial tensile and compressive strain on He migration in W-Ta-Cr-V complex alloys have been systematically studied through first-principles calculations. Our results demonstrate that He atoms preferentially occupy the tetrahedral interstitial sites, with interstitial formation energies significantly reduced compared to pure W. The introduction of Ta, Cr, and V alloying elements markedly increases the He migration barriers, effectively suppressing He diffusion. Compressive strain increases the migration barriers, inhibiting He bubbles nucleation and growth, while tensile strain decreases the barriers, facilitating bubble formation. Compared to pure W, the W-Ta-Cr-V alloys exhibit both lower He interstitial formation energies and higher migration barriers, with further enhancement under compressive strain. Specifically, compressive strain of 6% increases the He migration barrier of the W-Ta-Cr-V alloy by 0.166 eV, which further widens the difference relative to pure W. These findings provide a theoretical explanation for the superior irradiation resistance of tungsten-based alloys observed experimentally and promote the understanding of irradiation damage in these alloys under strain.

Yielding transition under oscillatory shear in metallic glasses

Nannan Ren(任楠楠), Tiantian Meng(孟天天), Hui Huang(黄慧), Qunshuang Ma(马群双), Jun Fang(房军), Qin Li(李勤), and Weihuo Li(李维火)

Chin. Phys. B, 2026, 35 (1): 016103. DOI: 10.1088/1674-1056/ae2c6c

Abstract ( 21 )

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The yielding transition of amorphous solids remains a fundamental yet poorly understood issue in materials physics. In this work, we employ oscillatory shear to probe the yielding transition in metallic glasses (MGs) with various thermal histories. We identify three distinct deformation regimes depending on the applied strain amplitudes. Below the yield strain $\gamma_{y}$, the response is elastic and accompanied by aging, through reversible atomic rearrangements that preserve the material's initial memory of thermal history. Slightly above $\gamma_{y}$, the system undergoes a sharp transition during oscillatory cycles, indicated by a sudden rise in potential energy and non-affine displacement, along with the emergence of a shear band. Well above $\gamma_{y}$, plastic deformation dominates, driving samples of various initial stability toward a common steady state, while thermal histories are erased by irreversible rearrangements and shear band formation. These findings advance the understanding of failure mechanisms in MGs and shed light on tuning their mechanical performance in industrial applications involving cyclic loading.

Machine learning-assisted optimization of MTO basis sets

Zhiqiang Li(李志强), and Lei Wang(王蕾)

Chin. Phys. B, 2026, 35 (1): 016301. DOI: 10.1088/1674-1056/ae0a39

Abstract ( 43 )

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First-principles calculations based on density functional theory (DFT) have had a significant impact on chemistry, physics, and materials science, enabling in-depth exploration of the structural and electronic properties of a wide variety of materials. Among different implementations of DFT, the plane-wave method is widely used for periodic systems because of its high accuracy. However, this method typically requires a large number of basis functions for large systems, leading to high computational costs. Localized basis sets, such as the muffin-tin orbital (MTO) method, have been introduced to provide a more efficient description of electronic structure with a reduced basis set, albeit at the cost of reduced computational accuracy. In this work, we propose an optimization strategy using machine-learning techniques to automate MTO basis-set parameters, thereby improving the accuracy and efficiency of MTO-based calculations. Default MTO parameter settings primarily focus on lattice structure and give less consideration to element-specific differences. In contrast, our optimized parameters incorporate both structural and elemental information. Based on these converged parameters, we successfully recovered missing bands for CrTe₂. For the other three materials — Si, GaAs, and CrI₃ — we achieved band improvements of up to 2 eV. Furthermore, the generalization of the machine-learned method is validated by perturbation, strain, and elemental substitution, resulting in improved band structures. Additionally, lattice-constant optimization for GaAs using the converged parameters yields closer agreement with experiment.

Uniform wafer-scale MOCVD homoepitaxy of β-Ga₂O₃ on 2-inch (010) substrates

Xuanze Zhou(周选择), Haozhong Wu(吴昊中), Yuanjie Ding(丁元杰), Ziyuan Wang(王子原), Zhiyu Zhou(周智宇), Ning Xia(夏宁), Song Zhang(张嵩), Guangwei Xu(徐光伟), Hui Zhang(张辉), and Shibing Long(龙世兵)

Chin. Phys. B, 2026, 35 (1): 016801. DOI: 10.1088/1674-1056/ae12e0

Abstract ( 12 )

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The (010) orientation of $\beta $-Ga$_2$O$_3$ is a highly promising platform for next-generation lateral power electronics due to its superior theoretical transport properties. However, progress has been impeded by the unavailability of large-area substrates, limiting studies to small-scale samples. Leveraging the recent emergence of 2-inch wafers, we report the first demonstration of homoepitaxial growth on a 2-inch, Fe-doped semi-insulating (010) $\beta $-Ga$_2$O$_3$ substrate by metal-organic chemical vapor deposition (MOCVD). A systematic, wafer-scale characterization reveals the successful growth of a high-quality epitaxial film. High-resolution x-ray diffraction shows an excellent crystalline structure, with a rocking curve full-width ranging from 21.0 arcsec to 103.0 arcsec. Atomic force microscopy confirms an atomically smooth surface with a root-mean-square roughness below 1.53 nm, displaying a distinct step-flow growth mode across the wafer. Furthermore, mercury-probe capacitance-voltage mapping indicates a well-controlled carrier concentration of $\sim 2\times 10^{18}$ cm$^{-3}$ with a RSD of 5.12%. This work provides the first comprehensive assessment of 2-inch (010) Ga$_2$O$_3$ epitaxial wafers, validating a critical material platform for the development and future manufacturing of high-performance power devices.

Magnetic anisotropy in MnGe thin films and its evolution under external magnetic fields

Zhaohang Li(李朝航), Fanbao Meng(孟凡保), Kesen Zhao(赵科森), Tao Qi(齐涛), Shihao Liu(刘仕豪), Zongyao Huang(黄宗耀), Feixiong Quan(全飞熊), Zhiwei Wang(王智炜), Zhengjie Wang(王郑杰), Xigang Luo(罗习刚), Jianjun Ying(应剑俊), Yubin Hou(侯玉斌), Wenjie Meng(孟文杰), Qingyou Lu(陆轻铀), and Xianhui Chen(陈仙辉)

Chin. Phys. B, 2026, 35 (1): 016802. DOI: 10.1088/1674-1056/ae1191

Abstract ( 2 )

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Chiral magnets have attracted considerable attention due to their intricate magnetic properties, among which B20 compounds constitute a quintessential class that has gained significant focus, particularly in the study of skyrmions. MnGe, as a member of the B20 family, exhibits a more complex magnetic structure compared with other materials with similar crystal structures. In this work, we successfully synthesized high-quality MnGe thin films and characterized their magnetoresistance, $M$—$H$ curves, magneto-Seebeck effect, and magnetic force microscopy (MFM) images, all of which demonstrate pronounced magnetic anisotropy. Notably, the Seebeck coefficient exhibits a plateau at low magnetic fields when the magnetic field is applied in the film plane, indicating a field region in which the magnetic structure remains stable. MFM imaging further reveals magnetic transitions within the MnGe films when the magnetic field is oriented along the film plane. These findings are crucial for advancing our understanding of the magnetic ground state of MnGe and the evolution of its magnetic structure under an applied external magnetic field.

Facile fabrication of twisted MoS₂ bilayers by direct bonding

Yu-Tong Chen(陈雨彤), Jie-Ying Liu(刘杰英), Lan-Ying Zhou(周兰英), Hua Yu(余画), Tong Li(李童), Qing Guan(关清), Na Li(李娜), Yang Chai(柴扬), and Guang-Yu Zhang(张广宇)

Chin. Phys. B, 2026, 35 (1): 016803. DOI: 10.1088/1674-1056/ae1c23

Abstract ( 29 )

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When stacking two-dimensional (2D) materials with a lattice mismatch and/or a small twist, moiré superlattice emerges with fascinating electronic and optical properties. The fabrication of such stacked 2D materials usually requires multiple transfer and stack processes, assisted by a certain transfer medium which needs to be removed afterwards, and it is very challenging to maintain pristine and clean surfaces/interfaces for these stacked structures. In this work, we report a facile direct bonding method for fabrication of twisted MoS₂ bilayers with ultra-clean surfaces/interfaces. Novel interlayer interactions are revealed in the as-fabricated high-quality samples, leading to twist-angle related dispersion behavior of various Raman modes, such as layer breathing modes, shear modes and E_2g modes, as well as indirect bandgap excitons. Field-effect transistors (FETs) of twisted MoS₂ bilayers also exhibit angle-dependent performance, which could be attributed to the band structure evolution. This facile method holds significance for the future integration of pre-designed multilayer 2D materials and paves a way to explore underlying physical mechanisms and potential applications.

A metastable state mediates the surface disordering of ice Ih

Zixiang Yan(颜子翔), Jiani Hong(洪嘉妮), Ye Tian(田野), Tiancheng Liang(梁天成), Limei Xu(徐莉梅), and Ying Jiang(江颖)

Chin. Phys. B, 2026, 35 (1): 016804. DOI: 10.1088/1674-1056/ae360b

Abstract ( 3 )

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Ice premelting, the formation of a quasi-liquid layer on ice surfaces below the bulk melting point, plays a crucial role in various processes, ranging from glacier dynamics to ice friction and surface chemistry. Despite intensive research, the microscopic structure of the premelting layer and underlying molecular mechanisms remain poorly understood. In this work, we studied the temperature- and pressure-dependent structural disordering of crystalline Ih (0001) surface near the onset of premelting on the atomic scale by qPlus-based cryogenic atomic force microscopy. The linear correlation between the density of planar local structure (PLS) and the fraction of disordered surface region showed that the PLS mediated early-stage premelting by serving as a metastable seeding state. Notably, the associated surface disordering is cooperative, extending over an area of roughly $\sim 2 $~nm$^{2}$ around a PLS. We further found a striking structural similarity between the kinetic-trapped regime below the surface crystallization temperature ($T_{\rm c}$) and the premelting-dominated regime above $ T_{\rm c}$. As the deposition pressure increased, the characteristic temperature dependence was preserved, with only $T_{\rm c}$ shifting to higher values due to kinetic effects. Finally, we proposed a surface phase diagram for ice Ih (0001) based on our experimental observations.

Review of machine learning tight-binding models: Route to accurate and scalable electronic simulations

Jijie Zou(邹暨捷), Zhanghao Zhouyin(周寅张皓), Shishir Kumar Pandey, and Qiangqiang Gu(顾强强)

Chin. Phys. B, 2026, 35 (1): 017101. DOI: 10.1088/1674-1056/ae15ef

Abstract ( 55 )

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The rapid advancement of machine learning based tight-binding Hamiltonian (MLTB) methods has opened new avenues for efficient and accurate electronic structure simulations, particularly in large-scale systems and long-time scenarios. This review begins with a concise overview of traditional tight-binding (TB) models, including both (semi-)empirical and first-principles approaches, establishing the foundation for understanding MLTB developments. We then present a systematic classification of existing MLTB methodologies, grouped into two major categories: direct prediction of TB Hamiltonian elements and inference of empirical parameters. A comparative analysis with other ML-based electronic structure models is also provided, highlighting the advancement of MLTB approaches. Finally, we explore the emerging MLTB application ecosystem, highlighting how the integration of MLTB models with a diverse suite of post-processing tools from linear-scaling solvers to quantum transport frameworks and molecular dynamics interfaces is essential for tackling complex scientific problems across different domains. The continued advancement of this integrated paradigm promises to accelerate materials discovery and open new frontiers in the predictive simulation of complex quantum phenomena.

Sequential phase transformations in Ta_0.4Ti₂Zr alloy via tensile molecular dynamics simulations with deep potential

Hongyang Liu(刘洪洋), Rong Chen(陈荣), Bo Chen(陈博), Jingzhi He(贺靖之), Dongdong Kang(康冬冬), and Jiayu Dai(戴佳钰)

Chin. Phys. B, 2026, 35 (1): 017102. DOI: 10.1088/1674-1056/ae1e68

Abstract ( 25 )

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Understanding the complex deformation mechanisms of non-equimolar multi-principal element alloys (MPEAs) requires high-fidelity atomic-scale simulations. This study develops a deep potential (DP) model to enable molecular dynamics simulations of the Ta$_{0.4}$Ti$_{2}$Zr (Ta$_{0.4}$) alloy. Monte Carlo simulations using this potential reveal Ta atom precipitation in the Ta$_{0.4}$ alloy. Under uniaxial tensile loading along the [100] direction in the NPT ensemble, the alloy undergoes a remarkable sequence of phase transformations: an initial body-centered cubic (BCC$_{1}$) to face-centered cubic (FCC) transformation, followed by a reverse transformation from FCC to a distinct BCC phase (BCC$_{2}$), and finally a BCC$_{2}$ to hexagonal close-packed (HCP) transformation. Critically, the reverse FCC to BCC$_{2}$ transformation induces significant volume contraction. We demonstrate that the inversely transformed BCC$_{2}$ phase primarily accommodates compressive stress. Concurrently, the reorientation of BCC$_{2}$ crystals contributes substantially to the observed high strain hardening. These simulations provide atomic-scale insights into the dynamic structural evolution, sequential phase transformations, and stress partitioning during deformation of the Ta$_{0.4}$ alloy. The developed DP model and the revealed mechanisms offer fundamental theoretical guidance for accelerating the design of high-performance MPEAs.

Type-II Dirac nodal chain semimetal CrB₄

Xiao-Yao Hou(侯逍遥), Ze-Feng Gao(高泽峰), Peng-Jie Guo(郭朋杰), Jian-Feng Zhang(张建丰), and Zhong-Yi Lu(卢仲毅)

Chin. Phys. B, 2026, 35 (1): 017301. DOI: 10.1088/1674-1056/ae172b

Abstract ( 29 )

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Dirac nodal line semimetals with topologically protected drumhead surface states have attracted intense theoretical and experimental attention over a decade. However, the study of type-II Dirac nodal line semimetals is rare, especially the type-II nodal chain semimetals have not been confirmed by experiment due to the lack of ideal material platform. In this study, based on symmetry analysis and the first-principles electronic structure calculations, we predict that CrB₄ is an ideal type-II Dirac nodal chain semimetal protected by the mirror symmetry. Moreover, there are two nodal rings protected by both space-inversion and time-reversal symmetries in CrB₄. More importantly, in CrB₄ the topologically protected drumhead surface states span the entire Brillouin zone at the Fermi level. Considering the fact that CrB₄ has been synthesized experimentally and the spin-orbit coupling is very weak, CrB₄ provides an ideal material platform for studying the exotic properties of type-II Dirac nodal chain semimetals in experiment.

Hydrothermal synthesis and nonvolatile resistive switching properties of α-Fe₂O₃ nanosheet arrays

Zhi-Qiang Yu(余志强), Xin-Wei Zhao(赵新为), Bao-Sheng Liu(刘宝生), Tang-You Sun(孙堂友), and Zhi-Mou Xu(徐智谋)

Chin. Phys. B, 2026, 35 (1): 017302. DOI: 10.1088/1674-1056/adee88

Abstract ( 14 )

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A facile one-step hydrothermal method has been reported to synthesize the $\alpha $-Fe$_{2}$O$_{3}$ nanosheet arrays with the preferred orientation along the [104] direction on the ITO substrate. The $\alpha $-Fe$_{2}$O$_{3}$ nanosheet arrays-based W/$\alpha $-Fe$_{2}$O$_{3}$/ITO memristor has been achieved by depositing the circular W top electrodes on the $\alpha $-Fe$_{2}$O$_{3}$ nanosheet arrays. The as-prepared W/$\alpha $-Fe$_{2}$O$_{3}$/ITO memristor shows a reliable nonvolatile bipolar resistive switching behavior with the high resistance ratio of about 10$^{3}$ at the reading voltage of 0.1 V, good resistance retention over 10$^{3 }$ s, ultralow set voltage of $-0.6$ V and reset voltage of 0.7 V, and good durability. In addition, the tunneling conduction mechanism modified by the oxygen vacancies has been proposed and suggested to be responsible for the nonvolatile resistive switching behavior of the as-prepared W/$\alpha $-Fe$_{2}$O$_{3}$/ITO memristor. This work demonstrates that the as-prepared $\alpha $-Fe$_{2}$O$_{3}$ nanosheet arrays-based W/$\alpha $-Fe$_{2}$O$_{3}$/ITO memristor would be a promising candidate for further ultralow power nonvolatile memory applications.

Doping dependence of resistivity, upper critical field and its anisotropy in overdoped Ba_1-xK_xFe₂As₂ (x = 0.6-1) single crystals

Ke Shi(史可), Wenshan Hong(洪文山), Yang Li(李阳), Minjie Zhang(张敏杰), Yongqi Han(韩永琦), Yu Zhao(赵宇), Jiating Wu(吴嘉挺), Ze Wang(王泽), Langsheng Ling(凌浪生), Chuanying Xi(郗传英), Li Pi(皮雳), Huiqian Luo(罗会仟), and Zhaosheng Wang(王钊胜)

Chin. Phys. B, 2026, 35 (1): 017401. DOI: 10.1088/1674-1056/ae1df1

Abstract ( 29 )

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Temperature-dependent resistivity, upper critical field $H_{\rm c2}$ and its anisotropy in overdoped superconducting Ba$_{1-x}$K$_{x}$Fe$_{2}$As$_2$ ($x=0.6$-1) single crystals have been measured in steady magnetic fields up to 44 T and low temperatures down to 0.4 K. Analysis using both the quadratic term and power-law fitting demonstrates that the in-plane resistivity $\rho_{ab}(T)$ progressively approaches the Fermi-liquid $T^2$ behavior with increasing K doping and reaches a saturation plateau at $x \approx 0.8$. The temperature dependence of both $H^{ab}_{\rm{c2}}$ and $H^{c}_{\rm{c2}}$ follows the Werthamer-Helfand-Hohenberg model, incorporating orbital and spin paramagnetic effects. For $x \leq 0.8$, the orbital effect dominates for $H \parallel ab$, while the Pauli paramagnetic effect prevails for $H\parallel c$. For $x > 0.8$, the Pauli paramagnetic effect becomes dominant in both crystallographic directions. The anisotropy of $H_{\rm{c2}}(0)$ exhibits a discontinuity in its dependence on K doping concentration with a significant enhancement at $x=0.8$ and a maximum at $x=0.9$. These experimental results indicate that the electron correlation effect is enhanced in the heavily overdoped Ba$_{1-x}$K$_{x}$Fe$_{2}$As$_2$ system where the underlying symmetries are broken due to the Fermi surface reconstruction before $x=0.9$.

Micromagnetic simulation of μMAG standard problem No. 3: Evaluating the standard dipole-dipole interaction

A. K. F. Silva, D. C. Carvalho, H. S. Assis, and P. Z. Coura

Chin. Phys. B, 2026, 35 (1): 017501. DOI: 10.1088/1674-1056/ae1727

Abstract ( 26 )

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Cubic-shaped magnetic particles subjected to a dimensionless uniaxial anisotropy ($Q = 0.1$) aligned with one of the crystallographic axes provide an ideal system for investigating magnetic equilibrium states. In this system, three fundamental magnetization configurations are identified: (i) the flower state, (ii) the twisted flower state, and (iii) the vortex state. This problem corresponds to standard problem No. 3 proposed by the NIST Micromagnetics Modeling Group, widely adopted as a benchmark for validating computational micromagnetics methods. In this work, we approach the problem using a computational method based on direct dipolar interactions, in contrast to conventional techniques that typically compute the demagnetizing field via finite difference-based fast Fourier transform (FFT) methods, tensor grid approaches, or finite element formulations. Our results are compared with established literature data, focusing on the dimensionless parameter $\lambda=L/l_{\rm ex}$, where $L$ is the cube edge length and $l_{\rm ex}$ is the exchange length of the material. To analyze equilibrium state transitions, we systematically varied the size $L$ as a function of the simulation cell number $N$ and intercellular spacing $a$, determining the critical $\lambda$ value associated with configuration changes. Our simulations reveal that the transition between the twisted flower and vortex states occurs at $\lambda \approx 8.45$, consistent with values reported in the literature, validating our code (Grupo de Física da Matéria Condensada - UFJF), and shows that this standard problem can be resolved using only interaction dipolar of a direct way without the need for sophisticated additional calculations.

Temperature-dependent magnetotransport properties of CoFe₂O₄/Pt heterostructure

Haomang He(何浩茫), Ruijie Xu(徐睿劼), Anke Song(宋安柯), Zhongqiang Chen(陈中强), and Xuefeng Wang(王学锋)

Chin. Phys. B, 2026, 35 (1): 017502. DOI: 10.1088/1674-1056/ae181c

Abstract ( 25 )

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We report on the growth of CoFe₂O₄/Pt heterostructure and their magnetotransport properties. The magnetoresistance under high magnetic fields exhibits a sign change when the temperature increases from 5 K to 10 K. The anomalous Hall resistance decreases as the temperature increases. Furthermore, angle-dependent magnetoresistance indicates that the observed magnetotransport behaviors originate from the competition between the spin Hall magnetoresistance and magnetic proximity effect.

Anomalous Hall effect and Lifshitz transition in Fe₃Sn₂ nanosheets

Xue Yang(杨雪), Jijian Liu(刘继健), Xinyi Zheng(郑新义), Lei Xu(徐磊), Lihong Hu(胡利洪), Sicheng Zhou(周思成), Siyuan Zhou(周思远), Ximing Zhang(张栖铭), Bingbing Tong(仝冰冰), Jie Shen(沈洁), Zhaozheng Lyu(吕昭征), Xiunian Jing(景秀年), Fanming Qu(屈凡明), Peiling Li(李沛岭), Jiadong Zhou(周家东), Guangtong Liu(刘广同), and Li Lü(吕力)

Chin. Phys. B, 2026, 35 (1): 017503. DOI: 10.1088/1674-1056/ae101b

Abstract ( 24 )

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Fe$_{3}$Sn$_{2}$, a ferromagnetic metal with a kagome lattice, serves as an ideal platform for exploring topological electronic states and Berry curvature due to its unique band structure. However, systematic reports on the transport properties of Fe$_{3}$Sn$_{2}$ nanosheets remain scarce. We present temperature-dependent transport property measurements of Fe$_{3}$Sn$_{2}$ nanosheets synthesized via chemical vapor deposition on Si/SiO$_{2}$ substrates. The samples exhibit a robust anomalous Hall effect from 40 K to 300 K, along with a magnetoresistance sign reversal at 40 K at high magnetic fields, indicating a spin reorientation from in-plane to out-of-plane. Notably, a sharp crossover in the dominant transport contribution from electrons to holes near 200 K is observed, accompanied by distinct anomalous Hall behaviors in the two regimes, indicating a temperature-induced Lifshitz transition within the multi-band system. This divergence is potentially linked to a topological reconstruction of the Fermi surface across the transition. Our findings highlight the tunability of topological transport in two-dimensional kagome magnets and provide new insights into the interplay between band topology, dimensionality and magnetic order.

Optimization of the giant magneto-impedance effect in Fe₂₀Ni₈₀/Cu composite wires by Joule heating annealing

Xiaofeng Pu(濮晓凤), Chaobo Liu(刘超波), Zhoulu Yu(俞周路), Guozhi Chai(柴国志), Junchen Gao(高骏琛), Linchuan Wang(王琳川), Yongang Liu(刘永刚), and Daqiang Gao(高大强)

Chin. Phys. B, 2026, 35 (1): 017504. DOI: 10.1088/1674-1056/adfebd

Abstract ( 10 )

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Giant magnetoimpedance (GMI) sensors are increasingly employed in modern magnetic sensing technologies. However, improving the GMI performance of magnetic cores remains challenging due to intrinsic limitations in material properties and structural stability. In this work, we explore the use of Joule heating to enhance the GMI response of Fe$_{20}$Ni$_{80}$/Cu composite wires. By applying a current of 1.8 A for 10 min, notable improvements in magnetic domain uniformity and a reduction in domain spacing are observed. Under these conditions, GMI ratios reach 1870% in the non-diagonal mode and 1147% in the diagonal mode, respectively, highlighting their potential for applications in high-precision weak magnetic field sensing.

Structural phase transition and quasi-layered active-ion distribution suppress concentration quenching in Tb³⁺-activated KBi(MoO₄)₂

Mengyu Zhang(张梦宇), Shujing Pan(潘淑晶), Haitang Hu(胡海棠), Wenzhi Su(宿文志), Yong Zou(邹勇), Shoujun Ding(丁守军), and Qingli Zhang(张庆礼)

Chin. Phys. B, 2026, 35 (1): 017801. DOI: 10.1088/1674-1056/ae1c25

Abstract ( 24 )

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Conventional Tb$^{3+}$-doped phosphors typically suffer from concentration quenching once the doping level exceeds a critical threshold. Consequently, the development of Tb$^{3+}$ phosphors with intrinsic resistance to concentration quenching has become a key research focus. In this work, we successfully synthesized KBi(MoO$_{4}$)$_{2}$: $x$Tb$^{3+}$ ($x = 0$-100 at%) (denoted as KBM: $x$Tb$^{3+}$) phosphors via a high-temperature solid-state reaction. Remarkably, no concentration quenching was observed across the entire doping range. This anti-quenching behavior originates from the large Tb$^{3+}$-Tb$^{3+}$ interionic distance ($> 5$ Å) inherent to the quasi-layered crystal structure, which effectively suppresses multipole-interaction-mediated energy migration. At full Tb$^{3+}$ substitution ($x = 100$ at%), the material undergoes a structural phase transition from the monoclinic KBM phase to the triclinic $\alpha $-KTb(MoO$_{4}$)$_{2}$ ($\alpha $-KTM) phase. The $\alpha $-KTM phosphor exhibits excellent thermal stability (activation energy $=$ 0.6129 eV) and a single-exponential decay profile, whereas KBM: $x$Tb$^{3+}$ ($x < 100$%) display double-exponential decay behaviors, attributed to dual energy transfer pathways. These findings provide new insights into the luminescence mechanisms of high-concentration rare-earth-doped systems and offer guidance for designing next-generation anti-quenching phosphors.

EDIS: A simulation software for dynamic ion intercalation/deintercalation processes in electrode materials

Liqi Wang(王力奇), Ruijuan Xiao(肖睿娟), and Hong Li(李泓)

Chin. Phys. B, 2026, 35 (1): 018201. DOI: 10.1088/1674-1056/ae111b

Abstract ( 28 )

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As the core determinant of lithium-ion battery performance, electrode materials play a crucial role in defining the battery’s capacity, cycling stability, and durability. During charging and discharging, electrode materials undergo complex ion intercalation and deintercalation processes, accompanied by defect formation and structural evolution. However, the microscopic mechanisms underlying processes such as cation disordering, lattice oxygen loss, and stage structure formation are still not fully understood. To address these challenges, we have developed the Electrode Dynamic Ion Intercalation/Deintercalation Simulator (EDIS), a software platform designed to simulate the dynamic processes of ion intercalation and deintercalation in electrode materials. Leveraging high-precision machine learning potentials, EDIS can efficiently model structural evolution and lithium-ion diffusion behavior under various states of charge and discharge, achieving accuracy approaching that of quantum mechanical methods in relevant chemical spaces. The software supports quantitative analysis of how variations in lithium-ion concentration and distribution affect lithium-ion transport properties, enables evaluation of the impact of structural defects, and allows for tracking of both structural evolution and transport characteristics during continuous cycling. EDIS is versatile and can be extended to sodium-ion batteries and related systems. By enabling in-depth analysis of these microscopic processes, EDIS provides a robust theoretical tool for mechanistic studies and the rational design of high-performance electrode materials for next-generation lithium-ion batteries.

Superconducting nanowire single photon detector with efficiency over 90% at 2 μm wavelength

Zhen Wan(万震), Jia Huang(黄佳), Guangzhao Xu(徐光照), Yu Ding(丁钰), Xiaoyu Liu(刘晓宇), Yiming Pan(潘一铭), Hongxin Xu(徐鸿鑫), Hao Li(李浩), and Lixing You(尤立星)

Chin. Phys. B, 2026, 35 (1): 018501. DOI: 10.1088/1674-1056/ae1b79

Abstract ( 48 )

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We here report a high system detection efficiency (SDE) superconducting single-photon detector (SSPD) at 2 μm wavelength. The device integrates a SiO₂/Ta₂O₅ distributed Bragg reflector (DBR) and a sandwich-structured double-layer NbN nanowire to enhance the optical absorption efficiency. A cold development technique is implemented to optimize the superconducting nanowires with sub-40-nm linewidths, thus enhancing the intrinsic detection efficiency (IDE). The fabricated SSPD shows an SDE exceeding 90% at 2 μm wavelength. Moreover, the detector allows an operational working temperature of 2.2 K provided by a compact GM cryo-cooler. This detector delivers excellent performance at the 2 μm wavelength, and its optimized structural design implies promising potential for extending detection toward longer infrared bands. It thus holds value for advancing high-sensitivity quantum technologies, mid-infrared optical communications, and dark matter detection research.

Strong enhancement of spin-orbit torques and perpendicular magnetic anisotropy in [Pt_0.75Ti_0.25/Co–Ni multilayer/Ta]_n superlattices

Xiaomiao Yin(阴小苗), Zhengxiao Li(李政霄), Jun Kang(康俊), Changmin Xiong(熊昌民), and Lijun Zhu(朱礼军)

Chin. Phys. B, 2026, 35 (1): 018502. DOI: 10.1088/1674-1056/ae1c26

Abstract ( 20 )

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We report the development of the [Pt$_{0.75}$Ti$_{0.25}$/Co-Ni multilayer/Ta]$_{n}$ superlattice with strong spin-orbit torque, large perpendicular magnetic anisotropy, and remarkably low switching current density. We demonstrate that the efficiency of the spin-orbit torque increases nearly linearly with the repetition number $n$, which is in excellent agreement with the spin Hall effect of the Pt$_{0.75}$Ti$_{0.25}$ being essentially the only source of the observed spin-orbit torque. The perpendicular magnetic anisotropy field is also substantially enhanced by more than a factor of 2 as $n$ increases from 1 to 6. The [Pt$_{0.75}$Ti$_{0.25}$/Co-Ni multilayers/Ta]$_{n}$ superlattice additionally exhibits deterministic, low-current-density magnetization switching despite the very large total layer thicknesses. The unique combination of strong spin-orbit torque, robust perpendicular magnetic anisotropy, low-current-density switching, and excellent high thermal stability makes the [Pt$_{0.75}$Ti$_{0.25}$/Co-Ni multilayer/Ta]$_{n}$ superlattice a highly compelling material candidate for ultrafast, energy-efficient, and long-data-retention spintronic technologies.

Heavy-ions-induced failure mechanisms and structural damage in SiC MOSFETs under complex irradiation conditions

Yiping Xiao(肖一平), Chaoming Liu(刘超铭), Jiaming Zhou(周佳明), Le Gao(高乐), Mingzheng Wang(王铭峥), Tianqi Wang(王天琦), and Mingxue Huo(霍明学)

Chin. Phys. B, 2026, 35 (1): 018503. DOI: 10.1088/1674-1056/ae07ad

Abstract ( 20 )

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The failure mechanisms and structural damage of SiC MOSFETs induced by heavy ion irradiation were demonstrated. The findings reveal three degradation modes, depending on the drain voltage. At a relatively low voltage, the damage is triggered by the formation and activation of gate latent damage (LDs), with damage concentrated in the gate oxide. The second degradation mode involves permanent leakage current degradation, with damage progressively transitioning from the oxide to the SiC material as the drain voltage escalates. Ultimately, the device undergoes catastrophic burnout above certain voltages, characterized by the lattice temperature reaching the sublimation point of SiC, resulting in surface cavity and complete structural destruction. This paper presents a comprehensive investigation of SiC MOSFETs under heavy ion exposure, providing radiation resistance methods of SiC-based devices for aerospace applications.

Revealing the dynamic responses of Pb under shock loading based on DFT-accuracy machine learning potential

Enze Hou(侯恩则), Xiaoyang Wang(王啸洋), and Han Wang(王涵)

Chin. Phys. B, 2026, 35 (1): 018701. DOI: 10.1088/1674-1056/ae1726

Abstract ( 30 )

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Lead (Pb) is a typical low-melting-point ductile metal and serves as an important model material in the study of dynamic responses. Under shock-wave loading, its dynamic mechanical behavior comprises two key phenomena: plastic deformation and shock-induced phase transitions. The underlying mechanisms of these processes are still poorly understood. Revealing these mechanisms remains challenging for experimental approaches. Non-equilibrium molecular dynamics (NEMD) simulations are an alternative theoretical tool for studying dynamic responses, as they capture atomic-scale mechanisms such as defect evolution and deformation pathways. However, due to the limited accuracy of empirical interatomic potentials, the reliability of previous NEMD studies has been questioned. Using our newly developed machine learning potential for Pb-Sn alloys, we revisited the microstructural evolution in response to shock loading under various shock orientations. The results reveal that shock loading along the [001] orientation of Pb exhibits a fast, reversible, and massive phase transition and stacking-fault evolution. The behavior of Pb differs from previous studies by the absence of twinning during plastic deformation. Loading along the [011] orientation leads to slow, irreversible plastic deformation, and a localized FCC-BCC phase transition in the Pitsch orientation relationship. This study provides crucial theoretical insights into the dynamic mechanical response of Pb, offering a theoretical input for understanding the microstructure-performance relationship under extreme conditions.

Visual perception and density-sensitive interaction in active agent system

Fei Meng(孟飞), Weiqiang Ma(马维强), Run Cheng(程润), and Jun Wang(王骏)

Chin. Phys. B, 2026, 35 (1): 018702. DOI: 10.1088/1674-1056/adf4a7

Abstract ( 26 )

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This study extends the self-propelled particle (SPP) model by incorporating a limited vision cone and local density sensing. The results reveal that clusters can simultaneously exhibit velocity polarization and spatial cohesion within specific ranges of vision angle and density threshold. The dependence of the dynamical features, including the order parameter and density variation, on the threshold and visual cone is investigated. Furthermore, a critical threshold is identified, which governs the transition between ordered and disordered states and is closely linked to density fluctuations and noise intensity. The clustering results show that the model is explained by the chasing mechanism responsible for cluster formation, density, and shape. These results may stimulate practical applications in swarm maneuvering.

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