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15 May 2024, Volume 33 Issue 5 Previous issue    Next issue

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TOPICAL REVIEW—Heat conduction and its related interdisciplinary areas

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High-entropy alloys in thermoelectric application: A selective review Kai Ren(任凯), Wenyi Huo(霍文燚), Shuai Chen(陈帅), Yuan Cheng(程渊), Biao Wang(王彪), and Gang Zhang(张刚) Chin. Phys. B, 2024, 33 (5):  057202.  DOI: 10.1088/1674-1056/ad34c5 Abstract ( 136 )   HTML ( 6 )   PDF (1047KB) ( 128 )   Since the superior mechanical, chemical and physical properties of high-entropy alloys (HEAs) were discovered, they have gradually become new emerging candidates for renewable energy applications. This review presents the novel applications of HEAs in thermoelectric energy conversion. Firstly, the basic concepts and structural properties of HEAs are introduced. Then, we discuss a number of promising thermoelectric materials based on HEAs. Finally, the conclusion and outlook are presented. This article presents an advanced understanding of the thermoelectric properties of HEAs, which provides new opportunities for promoting their applications in renewable energy.

SPECIAL TOPIC—Heat conduction and its related interdisciplinary areas

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Dynamic response of a thermal transistor to time-varying signals Qinli Ruan(阮琴丽), Wenjun Liu(刘文君), and Lei Wang(王雷) Chin. Phys. B, 2024, 33 (5):  056301.  DOI: 10.1088/1674-1056/ad2dcc Abstract ( 93 )   HTML ( 4 )   PDF (805KB) ( 60 )   Thermal transistor, the thermal analog of an electronic transistor, is one of the most important thermal devices for microscopic-scale heat manipulating. It is a three-terminal device, and the heat current flowing through two terminals can be largely controlled by the temperature of the third one. Dynamic response plays an important role in the application of electric devices and also thermal devices, which represents the devices' ability to treat fast varying inputs. In this paper, we systematically study two typical dynamic responses of a thermal transistor, i.e., the response to a step-function input (a switching process) and the response to a square-wave input. The role of the length $L$ of the control segment is carefully studied. It is revealed that when $L$ is increased, the performance of the thermal transistor worsens badly. Both the relaxation time for the former process and the cutoff frequency for the latter one follow the power-law dependence on $L$ quite well, which agrees with our analytical expectation. However, the detailed power exponents deviate from the expected values noticeably. This implies the violation of the conventional assumptions that we adopt.

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Thermal management by manipulating electromagnetic parameters Yun Wang(王云), Di-Fei Liang(梁迪飞), Tian-Cheng Han(韩天成), and Long-Jiang Deng(邓龙江) Chin. Phys. B, 2024, 33 (5):  058403.  DOI: 10.1088/1674-1056/ad34c6 Abstract ( 107 )   HTML ( 9 )   PDF (1270KB) ( 69 )   Electromagnetic absorbing materials may convert electromagnetic energy into heat energy and dissipate it. However, in a high-power electromagnetic radiation environment, the temperature of the absorbing material rises significantly and even burns. It becomes critical to ensure electromagnetic absorption performance while minimizing temperature rise. Here, we systematically study the coupling mechanism between the electromagnetic field and the temperature field when the absorbing material is irradiated by electromagnetic waves. We find out the influence of the constitutive parameters of the absorbing materials (including uniform and non-uniform) on the temperature distribution. Finally, through a smart design, we achieve better absorption and lower temperature simultaneously. The accuracy of the model is affirmed as simulation results aligned with theoretical analysis. This work provides a new avenue to control the temperature distribution of absorbing materials.

SPECIAL TOPIC—Quantum computing and quantum sensing

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Quafu-RL: The cloud quantum computers based quantum reinforcement learning Yu-Xin Jin(靳羽欣), Hong-Ze Xu(许宏泽), Zheng-An Wang(王正安), Wei-Feng Zhuang(庄伟峰), Kai-Xuan Huang(黄凯旋), Yun-Hao Shi(时运豪), Wei-Guo Ma(马卫国), Tian-Ming Li(李天铭), Chi-Tong Chen(陈驰通), Kai Xu(许凯), Yu-Long Feng(冯玉龙), Pei Liu(刘培), Mo Chen(陈墨), Shang-Shu Li(李尚书), Zhi-Peng Yang(杨智鹏), Chen Qian(钱辰), Yun-Heng Ma(马运恒), Xiao Xiao(肖骁), Peng Qian(钱鹏), Yanwu Gu(顾炎武), Xu-Dan Chai(柴绪丹), Ya-Nan Pu(普亚南), Yi-Peng Zhang(张翼鹏), Shi-Jie Wei(魏世杰), Jin-Feng Zeng(曾进峰), Hang Li(李行), Gui-Lu Long(龙桂鲁), Yirong Jin(金贻荣), Haifeng Yu(于海峰), Heng Fan(范桁), Dong E. Liu(刘东), and Meng-Jun Hu(胡孟军) Chin. Phys. B, 2024, 33 (5):  050301.  DOI: 10.1088/1674-1056/ad3061 Abstract ( 201 )   HTML ( 3 )   PDF (990KB) ( 186 )   With the rapid advancement of quantum computing, hybrid quantum-classical machine learning has shown numerous potential applications at the current stage, with expectations of being achievable in the noisy intermediate-scale quantum (NISQ) era. Quantum reinforcement learning, as an indispensable study, has recently demonstrated its ability to solve standard benchmark environments with formally provable theoretical advantages over classical counterparts. However, despite the progress of quantum processors and the emergence of quantum computing clouds, implementing quantum reinforcement learning algorithms utilizing parameterized quantum circuits (PQCs) on NISQ devices remains infrequent. In this work, we take the first step towards executing benchmark quantum reinforcement problems on real devices equipped with at most 136 qubits on the BAQIS Quafu quantum computing cloud. The experimental results demonstrate that the policy agents can successfully accomplish objectives under modified conditions in both the training and inference phases. Moreover, we design hardware-efficient PQC architectures in the quantum model using a multi-objective evolutionary algorithm and develop a learning algorithm that is adaptable to quantum devices. We hope that the Quafu-RL can be a guiding example to show how to realize machine learning tasks by taking advantage of quantum computers on the quantum cloud platform.

SPECIAL TOPIC—Recent progress on kagome metals and superconductors

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Superconductivity in kagome metal ThRu3Si2 Yi Liu(刘艺), Jing Li(厉静), Wu-Zhang Yang(杨武璋), Jia-Yi Lu(卢佳依), Bo-Ya Cao(曹博雅), Hua-Xun Li(李华旬), Wan-Li Chai(柴万力), Si-Qi Wu(武思祺), Bai-Zhuo Li(李佰卓), Yun-Lei Sun(孙云蕾), Wen-He Jiao(焦文鹤), Cao Wang(王操), Xiao-Feng Xu(许晓峰), Zhi Ren(任之), and Guang-Han Cao(曹光旱) Chin. Phys. B, 2024, 33 (5):  057401.  DOI: 10.1088/1674-1056/ad1c5e Abstract ( 124 )   HTML ( 6 )   PDF (1560KB) ( 91 )   We report the physical properties of ThRu$_3$Si$_2$ featured with distorted Ru kagome lattice. The combined experiments of resistivity, magnetization and specific heat reveal bulk superconductivity with $T_{\rm{c}}= 3.8$ K. The specific heat jump and calculated electron-phonon coupling indicate a moderate coupled BCS superconductor. In comparison with LaRu$_3$Si$_2$, the calculated electronic structure in ThRu$_3$Si$_2$ shows an electron-doping effect with electron filling lifted from 100 meV below flat bands to 300 meV above it. This explains the lower superconducting transition temperature and weaker electron correlations observed in ThRu$_3$Si$_2$. Our work suggests the $T_{\rm{c}}$ and electronic correlations in the kagome superconductor could have an intimate connection with the flat bands.

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Enhanced anomalous Hall effect in kagome magnet YbMn6Sn6 with intermediate-valence ytterbium Longfei Li(李龙飞), Shengwei Chi(迟晟玮), Wenlong Ma(马文龙), Kaizhen Guo(郭凯臻), Gang Xu(徐刚), and Shuang Jia(贾爽) Chin. Phys. B, 2024, 33 (5):  057501.  DOI: 10.1088/1674-1056/ad322d Abstract ( 117 )   HTML ( 4 )   PDF (1841KB) ( 167 )   We report on the magnetization and anomalous Hall effect (AHE) in the high-quality single crystals of the kagome magnet YbMn$_{6}$Sn$_{6}$, where the spins of the Mn atoms in the kagome lattice order ferromagnetically and the intermediate-valence Yb atoms are nonmagnetic. The intrinsic mechanism plays a crucial role in the AHE, leading to an enhanced anomalous Hall conductivity (AHC) compared with the other rare-earth $R$Mn$_{6}$Sn$_{6}$ compounds. Our band structure calculation reveals a strong hybridization between the 4f electrons of Yb and conduction electrons.

DATA PAPER

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Prediction of impurity spectrum function by deep learning algorithm Ting Liu(刘婷), Rong-Sheng Han(韩榕生), and Liang Chen(陈亮) Chin. Phys. B, 2024, 33 (5):  057102.  DOI: 10.1088/1674-1056/ad3908 Abstract ( 148 )   HTML ( 3 )   PDF (1420KB) ( 111 )   By using the numerical renormalization group (NRG) method, we construct a large dataset with about one million spectral functions of the Anderson quantum impurity model. The dataset contains the density of states (DOS) of the host material, the strength of Coulomb interaction between on-site electrons ($U$), and the hybridization between the host material and the impurity site ($\varGamma$). The continued DOS and spectral functions are stored with Chebyshev coefficients and wavelet functions, respectively. From this dataset, we build seven different machine learning networks to predict the spectral function from the input data, DOS, $U$, and $\varGamma$. Three different evaluation indexes, mean absolute error (MAE), relative error (RE) and root mean square error (RMSE), are used to analyze the prediction abilities of different network models. Detailed analysis shows that, for the two kinds of widely used recurrent neural networks (RNNs), gate recurrent unit (GRU) has better performance than the long short term memory (LSTM) network. A combination of bidirectional GRU (BiGRU) and GRU has the best performance among GRU, BiGRU, LSTM, and BiLSTM. The MAE peak of ${\rm BiGRU+GRU}$ reaches 0.00037. We have also tested a one-dimensional convolutional neural network (1DCNN) with 20 hidden layers and a residual neural network (ResNet), we find that the 1DCNN has almost the same performance of the $\rm BiGRU+GRU$ network for the original dataset, while the robustness testing seems to be a little weak than ${\rm BiGRU+GRU}$ when we test all these models on two other independent datasets. The ResNet has the worst performance among all the seven network models. The datasets presented in this paper, including the large data set of the spectral function of Anderson quantum impurity model, are openly available at https://doi.org/10.57760/sciencedb.j00113.00192.

INSTRUMENTATION AND MEASUREMENT

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Microwave electrometry with Rydberg atoms in a vapor cell using microwave amplitude modulation Jian-Hai Hao(郝建海), Feng-Dong Jia(贾凤东), Yue Cui(崔越), Yu-Han Wang(王昱寒), Fei Zhou(周飞), Xiu-Bin Liu(刘修彬), Jian Zhang(张剑), Feng Xie(谢锋), Jin-Hai Bai(白金海), Jian-Qi You(尤建琦), Yu Wang(王宇), and Zhi-Ping Zhong(钟志萍) Chin. Phys. B, 2024, 33 (5):  050702.  DOI: 10.1088/1674-1056/ad1a8f Abstract ( 137 )   HTML ( 2 )   PDF (2052KB) ( 118 )   We have theoretically and experimentally studied the dispersive signal of the Rydberg atomic electromagnetically-induced transparency (EIT) Autler-Townes (AT) splitting spectra obtained using amplitude modulation of the microwave (MW) electric field. In addition to the two zero-crossing points interval $\Delta f_{\text{zeros}}$, the dispersion signal has two positive maxima with an interval defined as the shoulder interval $\Delta f_{\text{sho}}$, which is theoretically expected to be used to measure a much weaker MW electric field. The relationship of the MW field strength $E_{\text{MW}}$ and $\Delta f_{\text{sho}}$ is experimentally studied at the MW frequencies of 31.6 GHz and 9.2 GHz respectively. The results show that $\Delta f_{\text{sho}}$ can be used to characterize the much weaker $E_{\text{MW}}$ than that of $\Delta f_{\text{zeros}}$ and the traditional EIT-AT splitting interval $\Delta f_{\text{m}}$; the minimum $E_{\text{MW}}$ measured by $\Delta f_{\text{sho}}$ is about 30 times smaller than that by $\Delta f_{\text{m}}$. As an example, the minimum $E_{\text{MW}}$ at 9.2 GHz that can be characterized by $\Delta f_{\text{sho}}$ is 0.056mV/cm, which is the minimum value characterized by the frequency interval using a vapor cell without adding any auxiliary fields. The proposed method can improve the weak limit and sensitivity of $E_{\text{MW}}$ measured by the spectral frequency interval, which is important in the direct measurement of weak $E_{\text{MW}}$.

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FPGA and computer-vision-based atom tracking technology for scanning probe microscopy Feng-Du Yu(俞风度), Li Liu(刘利), Su-Ke Wang(王肃珂), Xin-Biao Zhang(张新彪), Le Lei(雷乐), Yuan-Zhi Huang(黄远志), Rui-Song Ma(马瑞松), and Qing Huan(郇庆) Chin. Phys. B, 2024, 33 (5):  050705.  DOI: 10.1088/1674-1056/ad34cb Abstract ( 99 )   HTML ( 2 )   PDF (2432KB) ( 88 )   Atom tracking technology enhanced with innovative algorithms has been implemented in this study, utilizing a comprehensive suite of controllers and software independently developed domestically. Leveraging an on-board field-programmable gate array (FPGA) with a core frequency of 100 MHz, our system facilitates reading and writing operations across 16 channels, performing discrete incremental proportional-integral-derivative (PID) calculations within 3.4 microseconds. Building upon this foundation, gradient and extremum algorithms are further integrated, incorporating circular and spiral scanning modes with a horizontal movement accuracy of 0.38 pm. This integration enhances the real-time performance and significantly increases the accuracy of atom tracking. Atom tracking achieves an equivalent precision of at least 142 pm on a highly oriented pyrolytic graphite (HOPG) surface under room temperature atmospheric conditions. Through applying computer vision and image processing algorithms, atom tracking can be used when scanning a large area. The techniques primarily consist of two algorithms: the region of interest (ROI)-based feature matching algorithm, which achieves 97.92% accuracy, and the feature description-based matching algorithm, with an impressive 99.99% accuracy. Both implementation approaches have been tested for scanner drift measurements, and these technologies are scalable and applicable in various domains of scanning probe microscopy with broad application prospects in the field of nanoengineering.

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High-frequency microwave cavity design for high-mass dark matter axion searches Chi Zhang(张驰), Jia Wang(王佳), Chunguang Li(李春光), Shiguang Chen(陈石广), Hang Cheng(程航), Liang Sun(孙亮), and Yun Wu(吴云) Chin. Phys. B, 2024, 33 (5):  054211.  DOI: 10.1088/1674-1056/ad34ca Abstract ( 103 )   HTML ( 2 )   PDF (1186KB) ( 73 )   The haloscope based on the $\rm TM_{010}$ mode cavity is a well-established technique for detecting QCD axions. However, the method has limitations in detecting high-mass axion due to significant volume loss in the high-frequency cavity. Utilizing a higher-order mode cavity can effectively reduce the volume loss of the high-frequency cavity. The rotatable dielectric pieces as a tuning mechanism can compensate for the degradation of the form factor of the higher-order mode. Nevertheless, the introduction of dielectric causes additional volume loss. To address these issues, this paper proposes a novel design scheme by adding a central metal rod to the higher-order mode cavity tuned by dielectrics, which improves the performance of the haloscope due to the increased effective volume of the cavity detector. The superiority of the novel design is demonstrated by comparing its simulated performance with previous designs. Moreover, the feasibility of the scheme is verified by the full-wave simulation results of the mechanical design model.

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Design and implementation of the monochromator shielding for the cold neutron spectrometers XINGZHI and BOYA Jinchen Wang(汪晋辰), Juanjuan Liu(刘娟娟), Daye Xu(徐大业), Florian Grünauer, Lijie Hao(郝丽杰), Yuntao Liu(刘蕴韬), Hongxia Zhang(张红霞), Peng Cheng(程鹏), and Wei Bao(鲍威) Chin. Phys. B, 2024, 33 (5):  057801.  DOI: 10.1088/1674-1056/ad3629 Abstract ( 105 )   HTML ( 2 )   PDF (3809KB) ( 79 )   An innovative monochromator shielding is designed and implemented for the cold neutron spectrometers XINGZHI and BOYA operated by Renmin University of China at China Advanced Research Reactor. Via Monte Carlo simulations and careful mechanical designs, a shielding configuration has been successfully developed to satisfy safety requirements of below 3 μSv/h dose rate at its exterior, meanwhile fulfilling space, floor load and nonmagnetic requirements. Composite materials are utilized to form the sandwich-type shielding walls: the inner layer of boron carbide rubber, the middle layer of steel-encased lead and the outer layer of borated polyethylene. Special-shaped liftable shielding blocks are incorporated to facilitate a continuous adjustment of the neutron energy while preventing radiation leakage. Our work has demonstrated that by utilizing composite shielding materials, along with the sandwich structure and liftable shielding blocks, a compact and lightweight shielding solution can be achieved. This enables the realization of advanced neutron scattering instruments that provide expanded space of measurement, larger energy and momentum coverage, and higher flux on the sample. This shielding represents the first of its kind in neutron scattering instruments in China. Following its successful operation, it has been subsequently employed by other neutron instruments across the country.

COMPUTATIONAL PROGRAMS FOR PHYSICS

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Quafu-Qcover: Explore combinatorial optimization problems on cloud-based quantum computers Hong-Ze Xu(许宏泽), Wei-Feng Zhuang(庄伟峰), Zheng-An Wang(王正安), Kai-Xuan Huang(黄凯旋), Yun-Hao Shi(时运豪), Wei-Guo Ma(马卫国), Tian-Ming Li(李天铭), Chi-Tong Chen(陈驰通), Kai Xu(许凯), Yu-Long Feng(冯玉龙), Pei Liu(刘培), Mo Chen(陈墨), Shang-Shu Li(李尚书), Zhi-Peng Yang(杨智鹏), Chen Qian(钱辰), Yu-Xin Jin(靳羽欣), Yun-Heng Ma(马运恒), Xiao Xiao(肖骁), Peng Qian(钱鹏), Yanwu Gu(顾炎武), Xu-Dan Chai(柴绪丹), Ya-Nan Pu(普亚南), Yi-Peng Zhang(张翼鹏), Shi-Jie Wei(魏世杰), Jin-Feng Zeng(增进峰), Hang Li(李行), Gui-Lu Long(龙桂鲁), Yirong Jin(金贻荣), Haifeng Yu(于海峰), Heng Fan(范桁), Dong E. Liu(刘东), and Meng-Jun Hu(胡孟军) Chin. Phys. B, 2024, 33 (5):  050302.  DOI: 10.1088/1674-1056/ad18ab Abstract ( 144 )   HTML ( 2 )   PDF (2109KB) ( 157 )   We introduce Quafu-Qcover, an open-source cloud-based software package developed for solving combinatorial optimization problems using quantum simulators and hardware backends. Quafu-Qcover provides a standardized and comprehensive workflow that utilizes the quantum approximate optimization algorithm (QAOA). It facilitates the automatic conversion of the original problem into a quadratic unconstrained binary optimization (QUBO) model and its corresponding Ising model, which can be subsequently transformed into a weight graph. The core of Qcover relies on a graph decomposition-based classical algorithm, which efficiently derives the optimal parameters for the shallow QAOA circuit. Quafu-Qcover incorporates a dedicated compiler capable of translating QAOA circuits into physical quantum circuits that can be executed on Quafu cloud quantum computers. Compared to a general-purpose compiler, our compiler demonstrates the ability to generate shorter circuit depths, while also exhibiting superior speed performance. Additionally, the Qcover compiler has the capability to dynamically create a library of qubits coupling substructures in real-time, utilizing the most recent calibration data from the superconducting quantum devices. This ensures that computational tasks can be assigned to connected physical qubits with the highest fidelity. The Quafu-Qcover allows us to retrieve quantum computing sampling results using a task ID at any time, enabling asynchronous processing. Moreover, it incorporates modules for results preprocessing and visualization, facilitating an intuitive display of solutions for combinatorial optimization problems. We hope that Quafu-Qcover can serve as an instructive illustration for how to explore application problems on the Quafu cloud quantum computers.

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Literature classification and its applications in condensed matter physics and materials science by natural language processing Siyuan Wu(吴思远), Tiannian Zhu(朱天念), Sijia Tu(涂思佳), Ruijuan Xiao(肖睿娟), Jie Yuan(袁洁), Quansheng Wu(吴泉生), Hong Li(李泓), and Hongming Weng(翁红明) Chin. Phys. B, 2024, 33 (5):  050704.  DOI: 10.1088/1674-1056/ad3c30 Abstract ( 152 )   HTML ( 3 )   PDF (681KB) ( 95 )   The exponential growth of literature is constraining researchers' access to comprehensive information in related fields. While natural language processing (NLP) may offer an effective solution to literature classification, it remains hindered by the lack of labelled dataset. In this article, we introduce a novel method for generating literature classification models through semi-supervised learning, which can generate labelled dataset iteratively with limited human input. We apply this method to train NLP models for classifying literatures related to several research directions, i.e., battery, superconductor, topological material, and artificial intelligence (AI) in materials science. The trained NLP `battery' model applied on a larger dataset different from the training and testing dataset can achieve F1 score of 0.738, which indicates the accuracy and reliability of this scheme. Furthermore, our approach demonstrates that even with insufficient data, the not-well-trained model in the first few cycles can identify the relationships among different research fields and facilitate the discovery and understanding of interdisciplinary directions.

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DSAS: A new macromolecular substructure solution program based on the modified phase-retrieval algorithm Xingke Fu(付兴科), Zhenxi Tan(谭振希), Zhi Geng(耿直), Qian Liu(刘茜), and Wei Ding(丁玮) Chin. Phys. B, 2024, 33 (5):  056102.  DOI: 10.1088/1674-1056/ad3c33 Abstract ( 124 )   HTML ( 2 )   PDF (1091KB) ( 186 )   Considering the pivotal role of single-wavelength anomalous diffraction (SAD) in macromolecular crystallography, our objective was to introduce {DSAS}, a novel program designed for efficient anomalous scattering substructure determination. DSAS stands out with its core components: a modified phase-retrieval algorithm and automated parameter tuning. The software boasts an intuitive graphical user interface (GUI), facilitating seamless input of essential data and real-time monitoring. Extensive testing on DSAS has involved diverse datasets, encompassing proteins, nucleic acids, and various anomalous scatters such as sulfur (S), selenium (Se), metals, and halogens. The results confirm {DSAS}'s exceptional performance in accurately determining heavy atom positions, making it a highly effective tool in the field.

REVIEW

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A historical overview of nano-optics: From near-field optics to plasmonics Miao-Yi Deng(邓妙怡), and Xing Zhu(朱星) Chin. Phys. B, 2024, 33 (5):  050703.  DOI: 10.1088/1674-1056/ad2a77 Abstract ( 129 )   HTML ( 0 )   PDF (7732KB) ( 93 )   Nano-optics is an emergent research field in physics that appeared in the 1980s, which deals with light-matter optical interactions at the nanometer scale. In early studies of nano-optics, the main concern focus is to obtain higher optical resolution over the diffraction limit. The researches of near-field imaging and spectroscopy based on scanning near-field optical microscopy (SNOM) are developed. The exploration of improving SNOM probe for near-field detection leads to the emergence of surface plasmons. In the sense of resolution and wider application, there has been a significant transition from seeking higher resolution microscopy to plasmonic near-field modulations in the nano-optics community during the nano-optic development. Nowadays, studies of nano-optics prefer the investigation of plasmonics in different material systems. In this article, the history of the development of near-field optics is briefly reviewed. The difficulties of conventional SNOM to achieve higher resolution are discussed. As an alternative solution, surface plasmons have shown the advantages of higher resolution, wider application, and flexible nano-optical modulation for new devices. The typical studies in different periods are introduced and characteristics of nano-optics in each stage are analyzed. In this way, the evolution progress from near-field optics to plasmonics of nano-optics research is presented. The future development of nano-optics is discussed then.

RAPID COMMUNICATION

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Dynamical localization in a non-Hermitian Floquet synthetic system Hot! Han Ke(可汗), Jiaming Zhang(张嘉明), Liang Huo(霍良), and Wen-Lei Zhao(赵文垒) Chin. Phys. B, 2024, 33 (5):  050507.  DOI: 10.1088/1674-1056/ad36bb Abstract ( 147 )   HTML ( 6 )   PDF (761KB) ( 219 )   We investigate the non-Hermitian effects on quantum diffusion in a kicked rotor model where the complex kicking potential is quasi-periodically modulated in the time domain. The synthetic space with arbitrary dimension can be created by incorporating incommensurate frequencies in the quasi-periodical modulation. In the Hermitian case, strong kicking induces the chaotic diffusion in the four-dimension momentum space characterized by linear growth of mean energy. We find that the quantum coherence in deep non-Hermitian regime can effectively suppress the chaotic diffusion and hence result in the emergence of dynamical localization. Moreover, the extent of dynamical localization is dramatically enhanced by increasing the non-Hermitian parameter. Interestingly, the quasi-energies become complex when the non-Hermitian parameter exceeds a certain threshold value. The quantum state will finally evolve to a quasi-eigenstate for which the imaginary part of its quasi-energy is large most. The exponential localization length decreases with the increase of the non-Hermitian parameter, unveiling the underlying mechanism of the enhancement of the dynamical localization by non-Hermiticity.

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Layered kagome compound Na2Ni3S4 with topological flat band Hot! Junyao Ye(叶君耀), Yihao Lin(林益浩), Haozhe Wang(王浩哲), Zhida Song(宋志达), Ji Feng(冯济), Weiwei Xie(谢韦伟), and Shuang Jia(贾爽) Chin. Phys. B, 2024, 33 (5):  057103.  DOI: 10.1088/1674-1056/ad3431 Abstract ( 382 )   HTML ( 19 )   PDF (2643KB) ( 376 )   We report structural and electronic properties of Na$_2$Ni$_3$S$_4$, a quasi-two-dimensional compound composed of alternating layers of [Ni$_3$S$_4$]$^{2-}$ and Na$^{+}$. The compound features a remarkable Ni-based kagome lattice with a square planar configuration of four surrounding S atoms for each Ni atom. Magnetization and electrical measurements reveal a weak paramagnetic insulator with a gap of about 0.5 eV.Our band structure calculation highlights a set of topological flat bands of the kagome lattice derived from the rotated d$_{xz}$-orbital with $C_\mathrm{3}$ + $T$ symmetry in the presence of crystal-field splitting.

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Nonreciprocal transport in the superconducting state of the chiral crystal NbGe2 Hot! Yonglai Liu(刘永来), Xitong Xu(许锡童), Miao He(何苗), Haitian Zhao(赵海天), Qingqi Zeng(曾庆祺), Xingyu Yang(杨星宇), Youming Zou(邹优鸣), Haifeng Du(杜海峰), and Zhe Qu(屈哲) Chin. Phys. B, 2024, 33 (5):  057402.  DOI: 10.1088/1674-1056/ad334b Abstract ( 226 )   HTML ( 14 )   PDF (2451KB) ( 279 )   Due to the lack of inversion, mirror or other roto-inversion symmetries, chiral crystals possess a well-defined handedness which, when combined with time-reversal symmetry breaking from the application of magnetic fields, can give rise to directional dichroism of the electrical transport phenomena via the magnetochiral anisotropy. In this study, we investigate the nonreciprocal magneto-transport in microdevices of NbGe$_{2}$, a superconductor with structural chirality. A giant nonreciprocal signal from vortex motions is observed during the superconducting transition, with the ratio of nonreciprocal resistance to the normal resistance ${\gamma}$ reaching 6$\times10^{5}$~T$^{-1}$$\cdot$A$^{-1}$. Interestingly, the intensity can be adjusted and even sign-reversed by varying the current, the temperature, and the crystalline orientation. Our findings illustrate intricate vortex dynamics and offer ways of manipulation on the rectification effect in superconductors with structural chirality.

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Electronic structure and effective mass of pristine and Cl-doped CsPbBr3 Hot! Zhiyuan Wei(魏志远), Yu-Hao Wei(魏愉昊), Shendong Xu(徐申东), Shuting Peng(彭舒婷), Makoto Hashimoto, Donghui Lu(路东辉), Xu Pan(潘旭), Min-Quan Kuang(匡泯泉), Zhengguo Xiao(肖正国), and Junfeng He(何俊峰) Chin. Phys. B, 2024, 33 (5):  057403.  DOI: 10.1088/1674-1056/ad3c31 Abstract ( 156 )   HTML ( 3 )   PDF (5143KB) ( 169 )   Organic-inorganic lead halide perovskites (LHPs) have attracted great interest owing to their outstanding optoelectronic properties. Typically, the underlying electronic structure would determinate the physical properties of materials. But as for now, limited studies have been done to reveal the underlying electronic structure of this material system, comparing to the huge amount of investigations on the material synthesis. The effective mass of the valance band is one of the most important physical parameters which plays a dominant role in charge transport and photovoltaic phenomena. In pristine CsPbBr$_{3}$, the Fröhlich polarons associated with the Pb-Br stretching modes are proposed to be responsible for the effective mass renormalization. In this regard, it would be very interesting to explore the electronic structure in doped LHPs. Here, we report high-resolution angle-resolved photoemission spectroscopy (ARPES) studies on both pristine and Cl-doped CsPbBr$_{3}$. The experimental band dispersions are extracted from ARPES spectra along both $\bar{\varGamma}$-$\bar{M}$-$\bar{\varGamma }$ and $\bar{X}$-$\bar{M}$-$\bar{X}$ high symmetry directions. DFT calculations are performed and directly compared with the ARPES data. Our results have revealed the band structure of Cl-doped CsPbBr$_{3}$ for the first time, which have also unveiled the effective mass renormalization in the Cl-doped CsPbBr$_{3}$ compound. Doping dependent measurements indicate that the chlorine doping could moderately tune the renormalization strength. These results will help understand the physical properties of LHPs as a function of doping.

GENERAL

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Prediction of collapse process and tipping points for mutualistic and competitive networks with k-core method Dongli Duan(段东立), Feifei Bi(毕菲菲), Sifan Li(李思凡), Chengxing Wu(吴成星), Changchun Lv(吕长春), and Zhiqiang Cai(蔡志强) Chin. Phys. B, 2024, 33 (5):  050201.  DOI: 10.1088/1674-1056/ad3341 Abstract ( 92 )   HTML ( 0 )   PDF (3353KB) ( 111 )   Ecosystems generally have the self-adapting ability to resist various external pressures or disturbances, which is always called resilience. However, once the external disturbances exceed the tipping points of the system resilience, the consequences would be catastrophic, and eventually lead the ecosystem to complete collapse. We capture the collapse process of ecosystems represented by plant-pollinator networks with the $k$-core nested structural method, and find that a sufficiently weak interaction strength or a sufficiently large competition weight can cause the structure of the ecosystem to collapse from its smallest $k$-core towards its largest $k$-core. Then we give the tipping points of structure and dynamic collapse of the entire system from the one-dimensional dynamic function of the ecosystem. Our work provides an intuitive and precise description of the dynamic process of ecosystem collapse under multiple interactions, and provides theoretical insights into further avoiding the occurrence of ecosystem collapse.

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Evolutionary game dynamics of combining two different aspiration-driven update rules in structured populations Zhi-Hao Yang(杨智昊) and Yan-Long Yang(杨彦龙) Chin. Phys. B, 2024, 33 (5):  050203.  DOI: 10.1088/1674-1056/ad20d8 Abstract ( 88 )   HTML ( 0 )   PDF (1403KB) ( 79 )   In evolutionary games, most studies on finite populations have focused on a single updating mechanism. However, given the differences in individual cognition, individuals may change their strategies according to different updating mechanisms. For this reason, we consider two different aspiration-driven updating mechanisms in structured populations: satisfied-stay unsatisfied shift (SSUS) and satisfied-cooperate unsatisfied defect (SCUD). To simulate the game player's learning process, this paper improves the particle swarm optimization algorithm, which will be used to simulate the game player's strategy selection, i.e., population particle swarm optimization (PPSO) algorithms. We find that in the prisoner's dilemma, the conditions that SSUS facilitates the evolution of cooperation do not enable cooperation to emerge. In contrast, SCUD conditions that promote the evolution of cooperation enable cooperation to emerge. In addition, the invasion of SCUD individuals helps promote cooperation among SSUS individuals. Simulated by the PPSO algorithm, the theoretical approximation results are found to be consistent with the trend of change in the simulation results.

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Mixed convectional and chemical reactive flow of nanofluid with slanted MHD on moving permeable stretching/shrinking sheet through nonlinear radiation, energy omission Saleem Nasir, Sekson Sirisubtawee, Pongpol Juntharee, and Taza Gul Chin. Phys. B, 2024, 33 (5):  050204.  DOI: 10.1088/1674-1056/ac7dbf Abstract ( 106 )   HTML ( 0 )   PDF (2352KB) ( 59 )   Hybrid nanofluids are remarkable functioning liquids that are intended to reduce the energy loss while maximizing the heat transmission. In the involvement of suction and nonlinear thermal radiation effects, this study attempted to explore the energy transmission features of the inclined magnetohydrodynamic (MHD) stagnation flow of CNTs-hybrid nanofluid across the nonlinear permeable stretching or shrinking sheet. This work also included some noteworthy features like chemical reactions, variable molecular diffusivity, quadratic convection, viscous dissipation, velocity slip and heat omission assessment. Employing appropriate similarity components, the model equations were modified to ODEs and computed by using the HAM technique. The impact of various relevant flow characteristics on movement, heat and concentration profiles was investigated and plotted on a graph. Considering various model factors, the significance of drag friction, heat and mass transfer rate were also computed in tabular and graphical form. This leads to the conclusion that such factors have a considerable impact on the dynamics of fluid as well as other engineering measurements of interest. Furthermore, viscous forces are dominated by increasing the values of $\lambda_{\rm p} ,\delta_{\rm m} $ and $\delta_{\rm q} $, and as a result, ${F}'(\xi)$ accelerates while the opposite trend is observed for $M$ and $\phi $. The drag friction is boosted by the augmentation $M$, $\lambda_{\rm p} $ and $\phi $, but the rate of heat transfer declined. According to our findings, hybrid nanoliquid effects dominate that of ordinary nanofluid in terms of ${F}'(\xi)$, $\varTheta ( \xi )$ and $\phi (\xi)$ profiles. The HAM and the numerical technique (shooting method) were found to be in good agreement.

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Quantum correlations and entanglement in coupled optomechanical resonators with photon hopping via Gaussian interferometric power analysis Y. Lahlou, B. Maroufi, and M. Daoud Chin. Phys. B, 2024, 33 (5):  050303.  DOI: 10.1088/1674-1056/ad2a6e Abstract ( 103 )   HTML ( 0 )   PDF (2186KB) ( 71 )   Quantum correlations that surpass entanglement are of great importance in the realms of quantum information processing and quantum computation. Essentially, for quantum systems prepared in pure states, it is difficult to differentiate between quantum entanglement and quantum correlation. Nonetheless, this indistinguishability is no longer holds for mixed states. To contribute to a better understanding of this differentiation, we have explored a simple model for both generating and measuring these quantum correlations. Our study concerns two macroscopic mechanical resonators placed in separate Fabry-Pérot cavities, coupled through the photon hopping process. this system offers a comprehensively way to investigate and quantify quantum correlations beyond entanglement between these mechanical modes. The key ingredient in analyzing quantum correlation in this system is the global covariance matrix. It forms the basis for computing two essential metrics: the logarithmic negativity ($E_\mathcal{N}^{\rm m}$) and the Gaussian interferometric power ($\mathcal{P}_{\mathcal{G}}^{m}$). These metrics provide the tools to measure the degree of quantum entanglement and quantum correlations, respectively. Our study reveals that the Gaussian interferometric power ($\mathcal{P}_{\mathcal{G}}^{m}$) proves to be a more suitable metric for characterizing quantum correlations among the mechanical modes in an optomechanical quantum system, particularly in scenarios featuring resilient photon hopping.

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Ascertaining the influences of auxiliary qubits on the Einstein-Podolsky-Rosen steering and its directions Ling-Ling Xing(邢玲玲), Huan Yang(杨欢), Gang Zhang(张刚), and Min Kong(孔敏) Chin. Phys. B, 2024, 33 (5):  050304.  DOI: 10.1088/1674-1056/ad1927 Abstract ( 95 )   HTML ( 0 )   PDF (1558KB) ( 73 )   Einstein-Podolsky-Rosen (EPR) steering is an example of nontrivial quantum nonlocality and characteristic in the non-classical world. The directivity (or asymmetry) is a fascinating trait of EPR steering, and it is different from other quantum nonlocalities. Here, we consider the strategy in which two atoms compose a two-qubit X state, and the two atoms are owned by Alice and Bob, respectively. The atom of Alice suffers from a reservoir, and the atom of Bob couples with a bit flip channel. The influences of auxiliary qubits on EPR steering and its directions are revealed by means of the entropy uncertainty relation. The results indicate that EPR steering declines with growing time $t$ when adding fewer auxiliary qubits. The EPR steering behaves as damped oscillation when introducing more auxiliary qubits in the strong coupling regime. In the weak coupling regime, the EPR steering monotonously decreases as $t$ increases when coupling auxiliary qubits. The increases in auxiliary qubits are responsible for the fact that the steerability from Alice to Bob (or from Bob to Alice) can be more effectively revealed. Notably, the introductions of more auxiliary qubits can change the situation that steerability from Alice to Bob is certain to a situation in which steerability from Bob to Alice is certain.

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An anti-aliasing filtering of quantum images in spatial domain using a pyramid structure Kai Wu(吴凯), Rigui Zhou(周日贵), and Jia Luo(罗佳) Chin. Phys. B, 2024, 33 (5):  050305.  DOI: 10.1088/1674-1056/ad2504 Abstract ( 81 )   HTML ( 0 )   PDF (2443KB) ( 28 )   As a part of quantum image processing, quantum image filtering is a crucial technology in the development of quantum computing. Low-pass filtering can effectively achieve anti-aliasing effects on images. Currently, most quantum image filterings are based on classical domains and grayscale images, and there are relatively fewer studies on anti-aliasing in the quantum domain. This paper proposes a scheme for anti-aliasing filtering based on quantum grayscale and color image scaling in the spatial domain. It achieves the effect of anti-aliasing filtering on quantum images during the scaling process. First, we use the novel enhanced quantum representation (NEQR) and the improved quantum representation of color images (INCQI) to represent classical images. Since aliasing phenomena are more pronounced when images are scaled down, this paper focuses only on the anti-aliasing effects in the case of reduction. Subsequently, we perform anti-aliasing filtering on the quantum representation of the original image and then use bilinear interpolation to scale down the image, achieving the anti-aliasing effect. The constructed pyramid model is then used to select an appropriate image for upscaling to the original image size. Finally, the complexity of the circuit is analyzed. Compared to the images experiencing aliasing effects solely due to scaling, applying anti-aliasing filtering to the images results in smoother and clearer outputs. Additionally, the anti-aliasing filtering allows for manual intervention to select the desired level of image smoothness.

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Enhancing quantum temporal steering via frequency modulation Mengkai Wu(吴孟凯) and Weiwen Cheng(程维文) Chin. Phys. B, 2024, 33 (5):  050306.  DOI: 10.1088/1674-1056/ad2505 Abstract ( 77 )   HTML ( 0 )   PDF (892KB) ( 63 )   Various strategies have been proposed to harness and protect space-like quantum correlations in different models under decoherence. However, little attention has been given to temporal-like correlations, such as quantum temporal steering (TS), in this context. In this work, we investigate TS in a frequency-modulated two-level system coupled to a zero-temperature reservoir in both the weak and strong coupling regimes. We analyze the impact of various frequency-modulated parameters on the behavior of TS and non-Markovian. The results demonstrate that appropriate frequency-modulated parameters can enhance the TS of the two-level system, regardless of whether the system is experiencing Markovian or non-Markovian dynamics. Furthermore, a suitable ratio between modulation strength and frequency ( i.e., all zeroes of the $0$th Bessel function $J_{0}({\delta}/{\varOmega})$) can significantly enhance TS in the strong coupling regime. These findings indicate that efficient and effective manipulation of quantum TS can be achieved through a frequency-modulated approach.

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Quantum circuit-based proxy blind signatures: A novel approach and experimental evaluation on the IBM quantum cloud platform Xiaoping Lou(娄小平), Huiru Zan(昝慧茹), and Xuejiao Xu(徐雪娇) Chin. Phys. B, 2024, 33 (5):  050307.  DOI: 10.1088/1674-1056/ad22d5 Abstract ( 73 )   HTML ( 0 )   PDF (541KB) ( 29 )   This paper presents a novel approach to proxy blind signatures in the realm of quantum circuits, aiming to enhance security while safeguarding sensitive information. The main objective of this research is to introduce a quantum proxy blind signature (QPBS) protocol that utilizes quantum logical gates and quantum measurement techniques. The QPBS protocol is constructed by the initial phase, proximal blinding message phase, remote authorization and signature phase, remote validation, and de-blinding phase. This innovative design ensures a secure mechanism for signing documents without revealing the content to the proxy signer, providing practical security authentication in a quantum environment under the assumption that the CNOT gates are securely implemented. Unlike existing approaches, our proposed QPBS protocol eliminates the need for quantum entanglement preparation, thus simplifying the implementation process. To assess the effectiveness and robustness of the QPBS protocol, we conduct comprehensive simulation studies in both ideal and noisy quantum environments on the IBM quantum cloud platform. The results demonstrate the superior performance of the QPBS algorithm, highlighting its resilience against repudiation and forgeability, which are key security concerns in the realm of proxy blind signatures. Furthermore, we have established authentic security thresholds (82.102%) in the presence of real noise, thereby emphasizing the practicality of our proposed solution.

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General multi-attack detection for continuous-variable quantum key distribution with local local oscillator Zhuo Kang(康茁), Wei-Qi Liu(刘维琪), Jin Qi(齐锦), and Chen He(贺晨) Chin. Phys. B, 2024, 33 (5):  050308.  DOI: 10.1088/1674-1056/ad2bf2 Abstract ( 95 )   HTML ( 1 )   PDF (854KB) ( 57 )   Continuous-variable quantum key distribution with a local local oscillator (LLO CVQKD) has been extensively researched due to its simplicity and security. For practical security of an LLO CVQKD system, there are two main attack modes referred to as reference pulse attack and polarization attack presently. However, there is currently no general defense strategy against such attacks, and the security of the system needs further investigation. Here, we employ a deep learning framework called generative adversarial networks (GANs) to detect both attacks. We first analyze the data in different cases, derive a feature vector as input to a GAN model, and then show the training and testing process of the GAN model for attack classification. The proposed model has two parts, a discriminator and a generator, both of which employ a convolutional neural network (CNN) to improve accuracy. Simulation results show that the proposed scheme can detect and classify attacks without reducing the secret key rate and the maximum transmission distance. It only establishes a detection model by monitoring features of the pulse without adding additional devices.

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Non-Gaussianity detection of single-mode rotationally symmetric quantum states via cumulant method Shao-Hua Xiang(向少华), Li-Jun Huang(黄利军), and Xian-Wu Mi(米贤武) Chin. Phys. B, 2024, 33 (5):  050309.  DOI: 10.1088/1674-1056/ad2506 Abstract ( 80 )   HTML ( 0 )   PDF (703KB) ( 28 )   The non-Gaussianity of quantum states incarnates an important resource for improving the performance of continuous-variable quantum information protocols. We propose a novel criterion of non-Gaussianity for single-mode rotationally symmetric quantum states via the squared Frobenius norm of higher-order cumulant matrix for the quadrature distribution function. As an application, we study the non-Gaussianities of three classes of single-mode symmetric non-Gaussian states: a mixture of vacuum and Fock states, single-photon added thermal states, and even/odd Schrödinger cat states. It is shown that such a criterion is faithful and effective for revealing non-Gaussianity. We further extend this criterion to two cases of symmetric multi-mode non-Gaussian states and non-symmetric single-mode non-Gaussian states.

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Coulomb-assisted nonlocal electron transport between two pairs of Majorana bound states in a superconducting island Hao-Di Wang(王浩迪), Jun-Tong Ren(任俊潼), Hai-Feng Lü(吕海峰), and Sha-Sha Ke(柯莎莎) Chin. Phys. B, 2024, 33 (5):  050310.  DOI: 10.1088/1674-1056/ad2a68 Abstract ( 92 )   HTML ( 0 )   PDF (668KB) ( 47 )   We investigate the nonlocal transport modulated by Coulomb interactions in devices comprising two interacting Majorana wires, where both nanowires are in proximity to a mesoscopic superconducting (SC) island. Each Majorana bound state (MBS) is coupled to one lead via a quantum dot with resonant levels. In this device, the nonlocal correlations can be induced in the absence of Majorana energy splitting. We find that the negative differential conductance and giant current noise cross correlation could be induced, due to the interplay between nonlocality of MBSs and dynamical Coulomb blockade effect. This feature may provide a signature for the existence of the MBSs.

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Novel self-embedding holographic watermarking image encryption protection scheme Linian Wang(王励年), Nanrun Zhou(周楠润), Bo Sun(孙博), Yinghong Cao(曹颖鸿), and Jun Mou(牟俊) Chin. Phys. B, 2024, 33 (5):  050501.  DOI: 10.1088/1674-1056/ad1c5b Abstract ( 98 )   HTML ( 0 )   PDF (20103KB) ( 95 )   For digital image transmission security and information copyright, a new holographic image self-embedding watermarking encryption scheme is proposed. Firstly, the plaintext is converted to the RGB three-color channel, the corresponding phase hologram is obtained by holographic technology and the watermark is self-embedded in the frequency domain. Secondly, by applying the Hilbert transform principle and genetic center law, a complete set of image encryption algorithms is constructed to realize the encryption of image information. Finally, simulation results and security analysis indicate that the scheme can effectively encrypt and decrypt image information and realize the copyright protection of information. The introduced scheme can provide some support for relevant theoretical research, and has practical significance.

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Remote sensing image encryption algorithm based on novel hyperchaos and an elliptic curve cryptosystem Jing-Xi Tian(田婧希), Song-Chang Jin(金松昌), Xiao-Qiang Zhang(张晓强), Shao-Wu Yang(杨绍武), and Dian-Xi Shi(史殿习) Chin. Phys. B, 2024, 33 (5):  050502.  DOI: 10.1088/1674-1056/ad20d9 Abstract ( 111 )   HTML ( 0 )   PDF (4595KB) ( 52 )   Remote sensing images carry crucial ground information, often involving the spatial distribution and spatiotemporal changes of surface elements. To safeguard this sensitive data, image encryption technology is essential. In this paper, a novel Fibonacci sine exponential map is designed, the hyperchaotic performance of which is particularly suitable for image encryption algorithms. An encryption algorithm tailored for handling the multi-band attributes of remote sensing images is proposed. The algorithm combines a three-dimensional synchronized scrambled diffusion operation with chaos to efficiently encrypt multiple images. Moreover, the keys are processed using an elliptic curve cryptosystem, eliminating the need for an additional channel to transmit the keys, thus enhancing security. Experimental results and algorithm analysis demonstrate that the algorithm offers strong security and high efficiency, making it suitable for remote sensing image encryption tasks.

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Fractional-order heterogeneous memristive Rulkov neuronal network and its medical image watermarking application Dawei Ding(丁大为), Yan Niu(牛炎), Hongwei Zhang(张红伟), Zongli Yang(杨宗立), Jin Wang(王金), Wei Wang(王威), and Mouyuan Wang(王谋媛) Chin. Phys. B, 2024, 33 (5):  050503.  DOI: 10.1088/1674-1056/ad322b Abstract ( 240 )   HTML ( 1 )   PDF (5357KB) ( 81 )   This article proposes a novel fractional heterogeneous neural network by coupling a Rulkov neuron with a Hopfield neural network (FRHNN), utilizing memristors for emulating neural synapses. The study firstly demonstrates the coexistence of multiple firing patterns through phase diagrams, Lyapunov exponents (LEs), and bifurcation diagrams. Secondly, the parameter related firing behaviors are described through two-parameter bifurcation diagrams. Subsequently, local attraction basins reveal multi-stability phenomena related to initial values. Moreover, the proposed model is implemented on a microcomputer-based ARM platform, and the experimental results correspond to the numerical simulations. Finally, the article explores the application of digital watermarking for medical images, illustrating its features of excellent imperceptibility, extensive key space, and robustness against attacks including noise and cropping.

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Dynamics and synchronization of neural models with memristive membranes under energy coupling Jingyue Wan(万婧玥), Fuqiang Wu(吴富强), Jun Ma(马军), and Wenshuai Wang(汪文帅) Chin. Phys. B, 2024, 33 (5):  050504.  DOI: 10.1088/1674-1056/ad1dcc Abstract ( 128 )   HTML ( 1 )   PDF (4017KB) ( 104 )   Dynamical modeling of neural systems plays an important role in explaining and predicting some features of biophysical mechanisms. The electrophysiological environment inside and outside of the nerve cell is different. Due to the continuous and periodical properties of electromagnetic fields in the cell during its operation, electronic components involving two capacitors and a memristor are effective in mimicking these physical features. In this paper, a neural circuit is reconstructed by two capacitors connected by a memristor with periodical mem-conductance. It is found that the memristive neural circuit can present abundant firing patterns without stimulus. The Hamilton energy function is deduced using the Helmholtz theorem. Further, a neuronal network consisting of memristive neurons is proposed by introducing energy coupling. The controllability and flexibility of parameters give the model the ability to describe the dynamics and synchronization behavior of the system.

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Two-dimensional-lag complex logistic map with complex parameters and its encryption application Fangfang Zhang(张芳芳), Jinbo Wu(武金波), Lei Kou(寇磊), Fengying Ma(马凤英), Liming Wu(吴黎明), and Xue Zhang(张雪) Chin. Phys. B, 2024, 33 (5):  050505.  DOI: 10.1088/1674-1056/ad2a69 Abstract ( 96 )   HTML ( 0 )   PDF (1582KB) ( 123 )   With the rapid development of internet technology, security protection of information has become more and more prominent, especially information encryption. Considering the great advantages of chaotic encryption, we propose a 2D-lag complex logistic map with complex parameters (2D-LCLMCP) and corresponding encryption schemes. Firstly, we present the model of the 2D-LCLMCP and analyze its chaotic properties and system stability through fixed points, Lyapunov exponent, bifurcation diagram, phase diagram, etc. Secondly, a block cipher algorithm based on the 2D-LCLMCP is proposed, the plaintext data is preprocessed using a pseudorandom sequence generated by the 2D-LCLMCP. Based on the generalized Feistel cipher structure, a round function $F$ is constructed using dynamic S-box and DNA encoding rules as the core of the block cipher algorithm. The generalized Feistel cipher structure consists of two $F$ functions, four XOR operations, and one permutation operation per round. The symmetric dynamic round keys that change with the plaintext are generated by the 2D-LCLMCP. Finally, experimental simulation and performance analysis tests are conducted. The results show that the block cipher algorithm has low complexit, good diffusion and a large key space. When the block length is 64 bits, only six rounds of encryption are required to provide sufficient security and robustness against cryptographic attacks.

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Single-photon scattering and quantum entanglement of two giant atoms with azimuthal angle differences in a waveguide system Jin-Song Huang(黄劲松), Hong-Wu Huang(黄红武), Yan-Ling Li(李艳玲), and Zhong-Hui Xu(徐中辉) Chin. Phys. B, 2024, 33 (5):  050506.  DOI: 10.1088/1674-1056/ad2508 Abstract ( 98 )   HTML ( 0 )   PDF (1833KB) ( 28 )   We theoretically investigate coherent scattering of single photons and quantum entanglement of two giant atoms with azimuthal angle differences in a waveguide system. Using the real-space Hamiltonian, analytical expressions are derived for the transport spectra scattered by these two giant atoms with four azimuthal angles. Fano-like resonance can be exhibited in the scattering spectra by adjusting the azimuthal angle difference. High concurrence of the entangled state for two atoms can be implemented in a wide angle-difference range, and the entanglement of the atomic states can be switched on/off by modulating the additional azimuthal angle differences from the giant atoms. This suggests a novel handle to effectively control the single-photon scattering and quantum entanglement.

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TCAS-PINN: Physics-informed neural networks with a novel temporal causality-based adaptive sampling method Jia Guo(郭嘉), Haifeng Wang(王海峰), Shilin Gu(古仕林), and Chenping Hou(侯臣平) Chin. Phys. B, 2024, 33 (5):  050701.  DOI: 10.1088/1674-1056/ad21f3 Abstract ( 144 )   HTML ( 5 )   PDF (253833KB) ( 108 )   Physics-informed neural networks (PINNs) have become an attractive machine learning framework for obtaining solutions to partial differential equations (PDEs). PINNs embed initial, boundary, and PDE constraints into the loss function. The performance of PINNs is generally affected by both training and sampling. Specifically, training methods focus on how to overcome the training difficulties caused by the special PDE residual loss of PINNs, and sampling methods are concerned with the location and distribution of the sampling points upon which evaluations of PDE residual loss are accomplished. However, a common problem among these original PINNs is that they omit special temporal information utilization during the training or sampling stages when dealing with an important PDE category, namely, time-dependent PDEs, where temporal information plays a key role in the algorithms used. There is one method, called Causal PINN, that considers temporal causality at the training level but not special temporal utilization at the sampling level. Incorporating temporal knowledge into sampling remains to be studied. To fill this gap, we propose a novel temporal causality-based adaptive sampling method that dynamically determines the sampling ratio according to both PDE residual and temporal causality. By designing a sampling ratio determined by both residual loss and temporal causality to control the number and location of sampled points in each temporal sub-domain, we provide a practical solution by incorporating temporal information into sampling. Numerical experiments of several nonlinear time-dependent PDEs, including the Cahn-Hilliard, Korteweg-de Vries, Allen-Cahn and wave equations, show that our proposed sampling method can improve the performance. We demonstrate that using such a relatively simple sampling method can improve prediction performance by up to two orders of magnitude compared with the results from other methods, especially when points are limited.

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Dynamic analysis of a novel multilink-spring mechanism for vibration isolation and energy harvesting Jia-Heng Xie(谢佳衡), Tao Yang(杨涛), and Jie Tang(唐介) Chin. Phys. B, 2024, 33 (5):  050706.  DOI: 10.1088/1674-1056/ad21f6 Abstract ( 59 )   HTML ( 1 )   PDF (2125KB) ( 30 )   Due to technical limitations, existing vibration isolation and energy harvesting (VIEH) devices have poor performance at low frequency. This paper proposes a new multilink-spring mechanism (MLSM) that can be used to solve this problem. The VIEH performance of the MLSM under harmonic excitation and Gaussian white noise was analyzed. It was found that the MLSM has good vibration isolation performance for low-frequency isolation and the frequency band can be widened by adjusting parameters to achieve a higher energy harvesting power. By comparison with two special cases, the results show that the MLSM is basically the same as the other two oscillators in terms of vibration isolation but has better energy harvesting performance under multistable characteristics. The MLSM is expected to reduce the impact of vibration on high-precision sensitive equipment in some special sites such as subways and mines, and at the same time supply power to structural health monitoring devices.

ATOMIC AND MOLECULAR PHYSICS

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Spectroscopy and molecule opacity investigation on excited states of SiS Rui Li(李瑞), Haonan Lv(吕浩男), Jiqun Sang(桑纪群), Xiaohua Liu(刘晓华), Guiying Liang(梁桂颖), and Yong Wu(吴勇) Chin. Phys. B, 2024, 33 (5):  053101.  DOI: 10.1088/1674-1056/ad20dc Abstract ( 107 )   HTML ( 0 )   PDF (1001KB) ( 56 )   The SiS molecule, which plays a significant role in space, has attracted a great deal of attention for many years. Due to complex interactions among its low-lying electronic states, precise information regarding the molecular structure of SiS is limited. To obtain accurate information about the structure of its excited states, the high-precision multireference configuration interaction (MRCI) method has been utilized. This method is used to calculate the potential energy curves (PECs) of the 18$\Lambda $-S states corresponding to the lowest dissociation limit of SiS. The core-valence correlation effect, Davidson's correction and the scalar relativistic effect are also included to guarantee the precision of the MRCI calculation. Based on the calculated PECs, the spectroscopic constants of quasi-bound and bound electronic states are calculated and they are in accordance with previous experimental results. The transition dipole moments (TDMs) and dipole moments (DMs) are determined by the MRCI method. In addition, the abrupt variations of the DMs for the 1$^{5}\Sigma^{+}$ and 2$^{5}\Sigma^{+}$ states at the avoided crossing point are attributed to the variation of the electronic configuration. The opacity of SiS at a pressure of 100 atms is presented across a series of temperatures. With increasing temperature, the expanding population of excited states blurs the band boundaries.

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Theoretical investigation of excited dipole bound states of alkali-containing diatomic anions Yi Lian(连艺), Lidan Xiao(肖利丹), Lili Bian(边丽丽), Hai-Feng Xu(徐海峰), and Bing Yan(闫冰) Chin. Phys. B, 2024, 33 (5):  053102.  DOI: 10.1088/1674-1056/ad20de Abstract ( 89 )   HTML ( 1 )   PDF (708KB) ( 26 )   Information about electronic excited states of molecular anions plays an important role in investigating electron attachment and detachment processes. Here we present a high-level theoretical study of the electronic structures of 12 alkali-metal-containing diatomic anions $MX^{-}$ ($MX = {\rm LiH}$, LiF, LiCl, NaF, NaCl, NaBr, RbCl, KCl, KBr, RbI, KI and CsI). The equation-of-motion electron-attachment coupled-cluster singles and doubles (EOM-EA-CCSD) method is used to calculate the electron binding energies (EBEs) of 10 electronic excited states of each of the 12 molecule anions. With addition of different s-/p-/d-type diffusion functions in the basis set, we have identified possible excited dipole bound states (DBSs) of each anion. With the investigation of EBEs on the 12 $MX$s with dipole moment (DM) up to 12.1 D, we evaluate the dependence of the number of anionic excited DBSs on molecular DM. The results indicate that there are at least two or three DBSs of anions with a molecular DM larger than 7 D and a molecule with $\rm DM ＞ 10$ D can sustain a $\pi $-DBS of the anion. Our study has some implications for the excited DBS electronic states of alkali-metal-containing diatomic molecules.

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Vibronic effect study of 1A2 state of H2O and D2O Bei-Yuan Zhang(张倍源), Li-Han Wang(王礼涵), Jian-Hui Zhu(朱剑辉), Wei-Qing Xu(徐卫青), Zi-Ru Ma(马子茹), Xiao-Li Zhao(赵小利), Yong Wu(吴勇), and Lin-Fan Zhu(朱林繁) Chin. Phys. B, 2024, 33 (5):  053401.  DOI: 10.1088/1674-1056/ad24d9 Abstract ( 97 )   HTML ( 0 )   PDF (890KB) ( 60 )   The generalized oscillator strengths of the dipole-forbidden excitations of the ${}^{1}$A$_{2}$ of $\mathrm{H_2O}$ and $\mathrm{D_2O}$ were calculated with the time dependent density functional theory, by taking into account the vibronic effect. It is found that the vibronic effect converts the dipole-forbidden excitation of the ${}^{1}$A$_{2}$ into a dipole-allowed one, which enhances the intensities of the corresponding generalized oscillator strength in the small squared momentum transfer region. The present investigation shows that the vibronic effect of $\mathrm{H_2O}$ is slightly stronger than that of $\mathrm{D_2O}$, which exhibits a clear isotopic effect.

ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS

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Optical trapping capability of tornado circular Pearcey beams Na-Na Liu(刘娜娜), Xiao-Ying Tang(唐晓莹), Shun-Yu Liu(刘舜禹), and Yi Liang(梁毅) Chin. Phys. B, 2024, 33 (5):  054201.  DOI: 10.1088/1674-1056/ad3347 Abstract ( 114 )   HTML ( 0 )   PDF (5310KB) ( 115 )   We systemically investigate optical trapping capability of a kind of tornado waves on Rayleigh particles. Such tornado waves are named as tornado circular Pearcey beams (TCPBs) and produced by combining two circular Pearcey beams with different radii. Our theoretical exploration delves into various aspects, including the propagation dynamics, energy flux, orbital angular momentum, trapping force, and torque characteristics of TCPBs. The results reveal that the orbital angular momentum, trapping force, and torque of these beams can be finely tuned through the judicious manipulation of their topological charges ($l_{1}$ and $l_{2})$. Notably, we observe a precise control mechanism wherein the force diminishes with $|l_{1}+l_{2}|$ and $|l_{1}-l_{2}|$, while the torque exhibits enhancement by decreasing solely with $|l_{1}+l_{2}|$ or increasing with $|l_{1}-l_{2}|$. These results not only provide quantitative insights into the optical trapping performance of TCPBs but also serve as a valuable reference for the ongoing development of innovative photonic tools.

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Design of compact integrated diamond nitrogen-vacancy center quantum probe Sheng-Kai Xia(夏圣开), Wen-Tao Lu(卢文韬), Xu-Tong Zhao(赵旭彤), Ya-Wen Xue(薛雅文), Zeng-Bo Xu(许增博), Shi-Yu Ge(葛仕宇), Yang Wang(汪洋), Lin-Yan Yu(虞林嫣), Yu-Chen Bian(卞雨辰), Si-Han An(安思瀚), Bo Yang(杨博), Jian-Jun Xiang(向建军), and Guan-Xiang Du(杜关祥) Chin. Phys. B, 2024, 33 (5):  054202.  DOI: 10.1088/1674-1056/ad2bf6 Abstract ( 156 )   HTML ( 2 )   PDF (1184KB) ( 71 )   An integrated quantum probe for magnetic field imaging is proposed, where the nitrogen-vacancy (NV) center fixed at the fiber tip is located on the periphery of flexible ring resonator. Using flexible polyimide (PI) as the substrate medium, we design a circular microstrip antenna, which can achieve a bandwidth of 140 MHz at Zeeman splitting frequency of 2.87 GHz, specifically suitable for NV center experiments. Subsequently, this antenna is seamlessly fixed at a three-dimensional-printed cylindrical support, allowing the optical fiber tip to extend out of a dedicated aperture. To mitigate errors originating from processing, precise tuning within a narrow range can be achieved by adjusting the conformal amplitude. Finally, we image the microwave magnetic field around the integrated probe with high resolution, and determine the suitable area for placing the fiber tip (SAP).

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Extending microwave-frequency electric-field detection through single transmission peak method ing Liu(刘青), Jin-Zhan Chen(陈进湛), He Wang(王赫), Jie Zhang(张杰), Wei-Min Ruan(阮伟民), Guo-Zhu Wu(伍国柱), Shun-Yuan Zheng(郑顺元), Jing-Ting Luo(罗景庭), and Zhen-Fei Song(宋振飞) Chin. Phys. B, 2024, 33 (5):  054203.  DOI: 10.1088/1674-1056/ad2a6f Abstract ( 217 )   HTML ( 0 )   PDF (665KB) ( 73 )   The strength of microwave (MW) electric field can be observed with high precision by using the standard electromagnetically induced transparency and Aulter-Towns (EIT-AT) technique, when its frequency is resonant or nearly-resonant with the Rydberg transition frequency. As the detuning of MW field increases, one of the transmission peaks (single peak) is easier to measure due to its increased amplitude. It can be found that the central symmetry point of the two transmission peaks $f_{1/2 }$ is only related to the detuning of MW field $\varDelta_{\rm MW} $ and central symmetry point $f_{0 }$ of resonant MW field, satisfying the relation $f_{1/2} ={\varDelta_{\rm MW} }/{2}+f_{0} $. Thus, we demonstrate a single transmission peak method that the MW E-field can be determined by interval between the position of single peak and $f_{1/2}$. We use this method to measure continuous frequencies in a band from $-200$ MHz to 200 MHz of the MW field. The experimental results and theoretical analysis are presented to describe the effectiveness of this method. For 50 MHz,$< \varDelta_{\rm MW}< 200$ MHz, this method solves the problem that the AT splitting cannot be measured by using the standard EIT-AT techniques or multiple atomic-level Rydberg atom schemes.

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Superradiance of ultracold cesium Rydberg |65D5/2> → |66P3/2> Liping Hao(郝丽萍), Xiaoxuan Han(韩小萱), Suying Bai(白素英), Xiufen You(游秀芬), Yuechun Jiao(焦月春), and Jianming Zhao(赵建明) Chin. Phys. B, 2024, 33 (5):  054204.  DOI: 10.1088/1674-1056/ad20da Abstract ( 93 )   HTML ( 0 )   PDF (1081KB) ( 109 )   We investigate Rydberg $|65{\rm D}_{5/2}\rangle \to |66{\rm P}_{3/2}\rangle$ superradiance in dense ultracold cesium atoms, where the ground atoms are excited to $|65{\rm D}_{5/2}\rangle$ Rydberg states via two-photon excitation in a standard magneto-optical trap. The superradiant spectrum of $|65{\rm D}_{5/2}\rangle \to |66{\rm P}_{3/2}\rangle$ is obtained using the state-selective field ionization technique. We observe its dynamic evolution process by varying the delay time of ionization field $t_{\rm d}$. The results show that the evolution process of $|65{\rm D}_{5/2}\rangle \to |66{\rm P}_{3/2}\rangle$ is much shorter than its radiation lifetime at room temperature, which verifies the superradiance effect. The dependence of the superradiance process on Rydberg atoms number $N_{\rm e}$ and principal quantum number ${n}$ is investigated. The results show that the superradiance becomes faster with increasing $N_{\rm e}$, while it is suppressed for stronger van der Waals (vdW) interactions. Superradiance has potential applications in quantum technologies, and the Rydberg atom is an ideal medium for superradiance. Our system is effective for studying the strong two-body interaction between Rydberg atoms.

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Electromagnetic pulses produced by a picosecond laser interacting with solid targets Ai-Hui Niu(牛爱慧), Ning Kang(康宁), Guo-Xiao Xu(许国潇), Jia-Jie Xie(谢佳节), Jian Teng(滕建), Hui-Ya Liu(刘会亚), Ming-Ying Sun(孙明营), and Ting-Shuai Li(李廷帅) Chin. Phys. B, 2024, 33 (5):  054205.  DOI: 10.1088/1674-1056/ad1a95 Abstract ( 100 )   HTML ( 0 )   PDF (1493KB) ( 27 )   A high-power laser ablating solid targets induces giant electromagnetic pulses (EMPs), which are intimately pertinent to laser parameters, such as energy and pulse width. In this study, we reveal the features of EMPs generated from a picosecond (ps) laser irradiating solid targets at the SG-II picosecond petawatt (PSPW) laser facility. The laser energy and pulse, as well as target material and thickness, show determinative effects on the EMPs' amplitude. More intense EMPs are detected behind targets compared to those at the other three positions, and the EMP amplitude decreases from 90.09 kV/m to 17.8 kV/m with the gold target thickness increasing from 10 μm to 20 μm, which is suppressed when the laser pulse width is enlarged. The results are expected to provide more insight into EMPs produced by ps lasers coupling with targets and lay the foundation for an effective EMP shielding design in high-power laser infrastructures.

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A novel dual-channel thermo-optic locking method for the whispering gallery mode microresonator Wenjie Fan(范文杰), Wenyao Liu(刘文耀), Ziwen Pan(潘梓文), Rong Wang(王蓉), Lai Liu(刘来), Enbo Xing(邢恩博), Yanru Zhou(周彦汝), Jun Tang(唐军), and Jun Liu(刘俊) Chin. Phys. B, 2024, 33 (5):  054206.  DOI: 10.1088/1674-1056/ad225f Abstract ( 72 )   HTML ( 0 )   PDF (2848KB) ( 27 )   Mode locking can be effectively achieved by using the thermo-optic effects in the whispering gallery mode (WGM) optical microcavity, without the help of external equipment. Therefore, it has the advantages of small size, low integration costs, and self-locking, which shows great potential for application. However, the conventional single-channel microcavity thermal-locking method that relies solely on internal thermal balance will inevitably be disturbed by the external environment. This limitation affects the locking time and stability. Therefore, in this paper, we propose a new method for closed-loop thermal locking of a dual-channel microcavity. The thermal locking of the signal laser and the thermal regulation of the control laser are carried out respectively by synchronously drawing a dual-path tapered fiber. The theoretical model of the thermal dynamics of the dual-channel microcavity system is established, and the influence of the control-laser power on the thermal locking of the signal laser is confirmed. The deviation between the locking voltage of the signal laser and the set point value is used as a closed-loop feedback parameter to achieve long-term and highly stable mode locking of the signal laser. The results show that in the 2.63 h thermal-locking test, the locking stability is an order of magnitude higher than that of the single tapered fiber. This solution addresses the issue of thermal locking being disrupted by the external environment, and offers new possibilities for important applications such as spectroscopy and micro-optical sensor devices.

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A global model of intensity autocorrelation to determine laser pulse duration Yufei Peng(彭雨菲), Liqiang Liu(刘励强), Lihong Hong(洪丽红), and Zhiyuan Li(李志远) Chin. Phys. B, 2024, 33 (5):  054207.  DOI: 10.1088/1674-1056/ad1c57 Abstract ( 95 )   HTML ( 0 )   PDF (716KB) ( 62 )   We present a new global model of collinear autocorrelation based on second harmonic generation nonlinearity. The model is rigorously derived from the nonlinear coupled wave equation specific to the autocorrelation measurement configuration, without requiring a specific form of the incident pulse function. A rigorous solution of the nonlinear coupled wave equation is obtained in the time domain and expressed in a general analytical form. The global model fully accounts for the nonlinear interaction and propagation effects within nonlinear crystals, which are not captured by the classical local model. To assess the performance of the global model compared to the classic local model, we investigate the autocorrelation signals obtained from both models for different incident pulse waveforms and different full-widthes at half-maximum (FWHMs). When the incident pulse waveform is Lorentzian with an FWHM of 200 fs, the global model predicts an autocorrelation signal FWHM of 399.9 fs, while the classic local model predicts an FWHM of 331.4 fs. The difference between the two models is 68.6 fs, corresponding to an error of 17.2%. Similarly, for a sech-type incident pulse with an FWHM of 200 fs, the global model predicts an autocorrelation signal FWHM of 343.9 fs, while the local model predicts an FWHM of 308.8 fs. The difference between the two models is 35.1 fs, with an error of 10.2%. We further examine the behavior of the models for Lorentzian pulses with FWHMs of 100 fs, 200 fs and 500 fs. The differences between the global and local models are 17.1 fs, 68.6 fs and 86.0 fs, respectively, with errors approximately around 17%. These comparative analyses clearly demonstrate the superior accuracy of the global model in intensity autocorrelation modeling.

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Elliptically polarized high-order harmonic generation of Ar atom in an intense laser field Jie Hu(胡杰), Yi-Chen Wang(王一琛), Qiu-Shuang Jing(景秋霜), Wei Jiang(姜威), Ge-Wen Wang(王革文), Yi-Wen Zhao(赵逸文), Bo Xiao(肖礴), Hong-Jing Liang(梁红静), and Ri Ma(马日) Chin. Phys. B, 2024, 33 (5):  054208.  DOI: 10.1088/1674-1056/ad2604 Abstract ( 139 )   HTML ( 0 )   PDF (698KB) ( 106 )   High-order harmonic generation (HHG) of Ar atom in an elliptically polarized intense laser field is experimentally investigated in this work. Interestingly, the anomalous ellipticity dependence on the laser ellipticity ($\varepsilon $) in the lower-order harmonics is observed, specifically in the 13rd-order, which displays a maximal harmonic intensity at $\varepsilon \approx 0.1$, rather than at $\varepsilon = 0$ as expected. This contradicts the general trend of harmonic yield, which typically decreases with the increase of laser ellipticity. In this study, we attribute this phenomenon to the disruption of the symmetry of the wave function by the Coulomb effect, leading to the generation of a harmonic with high ellipticity. This finding provides valuable insights into the behavior of elliptically polarized harmonics and opens up a potential way for exploring new applications in ultrafast spectroscopy and light-matter interactions.

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Optimization of extreme ultraviolet vortex beam based on high harmonic generation Bo Xiao(肖礴), Yi-Wen Zhao(赵逸文), Fang-Jing Cheng(程方晶), Ge-Wen Wang(王革文), Wei Jiang(姜威), Yi-Chen Wang(王一琛), Jie Hu(胡杰), Hong-Jing Liang(梁红静), and Ri Ma(马日) Chin. Phys. B, 2024, 33 (5):  054209.  DOI: 10.1088/1674-1056/ad2bf0 Abstract ( 98 )   HTML ( 0 )   PDF (997KB) ( 89 )   In high harmonic generation (HHG), Laguerre-Gaussian (LG) beams are used to generate extreme ultraviolet (XUV) vortices with well-defined orbital angular momentum (OAM), which have potential applications in fields such as microscopy and spectroscopy. An experimental study on the HHG driven by vortex and Gaussian beams is conducted in this work. It is found that the intensity of vortex harmonics is positively correlated with the laser energy and gas pressure. The structure and intensity distribution of the vortex harmonics exhibit significant dependence on the relative position between the gas jet and the laser focus. The ring-like structures observed in the vortex harmonics, and the interference of quantum paths provide an explanation for the distinct structural characteristics. Moreover, by adjusting the relative position between the jet and laser focus, it is possible to discern the contributions from different quantum paths. The optimization of the HH vortex field is applicable to the XUV, which opens up a new way for exploiting the potential in optical spin or manipulating electrons by using the photon with tunable orbital angular momentum.

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Tunable artificial plasmonic nanolaser with wide spectrum emission operating at room temperature Peng Zhou(周鹏), Jia-Qi Guo(郭佳琦), Kun Liang(梁琨), Lei Jin(金磊), Xiong-Yu Liang(梁熊玉), Jun-Qiang Li(李俊强), Xu-Yan Deng(邓绪彦), Jian-Yu Qin(秦建宇), Jia-Sen Zhang(张家森), and Li Yu(于丽) Chin. Phys. B, 2024, 33 (5):  054210.  DOI: 10.1088/1674-1056/ad2dca Abstract ( 96 )   HTML ( 0 )   PDF (3646KB) ( 23 )   With the rapid development of information and communication technology, a key objective in the field of optoelectronic integrated devices is to reduce the nano-laser size and energy consumption. Photonics nanolasers are unable to exceed the diffraction limit and typically exhibit low modulation rates of several GHz. In contrast, plasmonic nanolaser utilizes highly confined surface plasmon polariton (SPP) mode that can exceed diffraction limit and their strong Purcell effect can accelerate the modulation rates to several THz. Herein, we propose a parametrically tunable artificial plasmonic nanolasers based on metal-insulator-semiconductor-insulator-metal (MISIM) structure, which demonstrates its ability to compress the mode field volume to $\lambda /14$. As the pump power increases, the proposed artificial plasmonic nanolaser exhibits 20-nm-wide output spectrum. Additionally, we investigate the effects of various cavity parameters on the nanolaser's output threshold, offering potentials for realizing low-threshold artificial plasmonic nanolasers. Moreover, we observe a blue shift in the center wavelength of the nanolaser output with thinner gain layer thickness, predominantly attributed to the increased exciton-photon coupling strength. Our work brings inspiration to several areas, including spaser-based interconnects, nano-LEDs, spontaneous emission control, miniaturization of photon condensates, eigenmode engineering of plasmonic nanolasers, and optimal design driven by artificial intelligence (AI).

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Experimental realization of fractal fretwork metasurface for sound anomalous modulation Jiajie He(何佳杰), Shumeng Yu(于书萌), Xue Jiang(江雪), and Dean Ta(他得安) Chin. Phys. B, 2024, 33 (5):  054301.  DOI: 10.1088/1674-1056/ad2dcd Abstract ( 94 )   HTML ( 1 )   PDF (1016KB) ( 83 )   Natural creatures and ancient cultures are full of potential sources to provide inspiration for applied sciences. Inspired by the fractal geometry in nature and the fretwork frame in ancient culture, here we design the acoustic metasurface to realize sound anomalous modulation, which manifests itself as an incident-dependent propagation behavior: sound wave propagating in the forward direction is allowed to transmit with high efficiency while in the backward direction is obviously suppressed. We quantitatively investigate the dependences of asymmetric transmission on the propagation direction, incident angle and operating frequency by calculating sound transmittance and energy contrast. This compact fractal fretwork metasurface for acoustic anomalous modulation would promote the development of integrated acoustic devices and expand versatile applications in acoustic communication and information encryption.

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Nonlinear interaction of head-on solitary waves in integrable and nonintegrable systems Shutian Zhang(张树甜), Shikun Liu(刘世鲲), Tengfei Jiao(矫滕菲), Min Sun(孙敏), Fenglan Hu(胡凤兰), and Decai Huang(黄德财) Chin. Phys. B, 2024, 33 (5):  054501.  DOI: 10.1088/1674-1056/ad1dcb Abstract ( 93 )   HTML ( 0 )   PDF (1022KB) ( 78 )   This study numerically investigates the nonlinear interaction of head-on solitary waves in a granular chain (a nonintegrable system) and compares the simulation results with the theoretical results in fluid (an integrable system). Three stages (the pre-in-phase traveling stage, the central-collision stage, and the post-in-phase traveling stage) are identified to describe the nonlinear interaction processes in the granular chain. The nonlinear scattering effect occurs in the central-collision stage, which decreases the amplitude of the incident solitary waves. Compared with the leading-time phase in the incident and separation collision processes, the lagging-time phase in the separation collision process is smaller. This asymmetrical nonlinear collision results in an occurrence of leading phase shifts of time and space in the post-in-phase traveling stage. We next find that the solitary wave amplitude does not influence the immediate space-phase shift in the granular chain. The space-phase shift of the post-in-phase traveling stage is only determined by the measurement position rather than the wave amplitude. The results are reversed in the fluid. An increase in solitary wave amplitude leads to decreased attachment, detachment, and residence times for granular chains and fluid. For the immediate time-phase shift, leading and lagging phenomena appear in the granular chain and the fluid, respectively. These results offer new knowledge for designing mechanical metamaterials and energy-mitigating systems.

PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES

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Characteristics of the electromagnetic wave propagation in magnetized plasma sheath and practical method for blackout mitigation Xiang Wu(吴翔), Jiahui Zhang(张珈珲), Guoxiang Dong(董果香), and Lei Shi(石磊) Chin. Phys. B, 2024, 33 (5):  055201.  DOI: 10.1088/1674-1056/ad24d4 Abstract ( 111 )   HTML ( 0 )   PDF (1146KB) ( 63 )   Magnetic window is considered as an effective method to solve the communication blackout issue. COMSOL software package based on the finite element method is utilized to simulate the propagation of right-handed circularly polarized wave in the magnetized plasma sheath. We assume a double Gaussian model of electron density and an exponential attenuation model of magnetic field. The propagation characteristics of right-handed circularly polarized wave are analyzed by the observation of the reflected, transmitted and loss coefficient. The numerical results show that the propagation of right-handed circularly polarized wave in the magnetized plasma sheath varies for different incident angles, collision frequencies, non-uniform magnetic fields and non-uniform plasma densities. We notice that reducing the wave frequency can meet the propagation conditions of whistle mode in the weak magnetized plasma sheath. And the transmittance of whistle mode is less affected by the variation of the electron density and the collision frequency. It can be used as a communication window.

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Effects of counter-current driven by electron cyclotron waves on neoclassical tearing mode suppression Qin Gao(高钦) and Ping-Wei Zheng(郑平卫) Chin. Phys. B, 2024, 33 (5):  055202.  DOI: 10.1088/1674-1056/ad23d3 Abstract ( 68 )   HTML ( 0 )   PDF (646KB) ( 20 )   Through theoretical analysis, we construct a physical model that includes the influence of counter-external driven current opposite to the plasma current direction in the neoclassical tearing mode (NTM). The equation is used with this model to obtain the modified Rutherford equation with co-current and counter-current contributions. Consistent with the reported experimental results, numerical simulations have shown that the localized counter external current can only partially suppress NTM when it is far from the resonant magnetic surface. Under some circumstances, the Ohkawa mechanism dominated current drive (OKCD) by electron cyclotron waves can concurrently create both co-current and counter-current. In this instance, the minimal electron cyclotron wave power that suppresses a particular NTM was calculated by the Rutherford equation. The result is marginally less than when taking co-current alone into consideration. As a result, to suppress NTM using OKCD, one only needs to align the co-current with a greater OKCD peak well with the resonant magnetic surface. The effect of its lower counter-current does not need to be considered because the location of the counter-current deviates greatly from the resonant magnetic surface.

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Model of self-generated magnetic field generation from relativistic laser interaction with solid targets Rui Yan(严睿), De-Bin Zou(邹德滨), Na Zhao(赵娜), Xiao-Hu Yang(杨晓虎), Xiang-Rui Jiang(蒋祥瑞), Li-Xiang Hu(胡理想), Xin-Rong Xu(徐新荣), Hong-Yu Zhou(周泓宇), Tong-Pu Yu(余同普), Hong-Bin Zhuo(卓红斌), Fu-Qiu Shao(邵福球), and Yan Yin(银燕) Chin. Phys. B, 2024, 33 (5):  055203.  DOI: 10.1088/1674-1056/ad333f Abstract ( 115 )   HTML ( 3 )   PDF (1503KB) ( 88 )   Generation of self-generated annular magnetic fields at the rear side of a solid target driven by relativistic laser pulse is investigated by using theoretical analysis and particle-in-cell simulations. The spatial strength distribution of magnetic fields can be accurately predicted by calculating the net flow caused by the superposition of source flow and return flow of hot electrons. The theoretical model established shows good agreement with the simulation results, indicating that the magnetic-field strength scales positively to the temperature of hot electrons. This provides us a way to improve the magnetic-field generation by using a micro-structured plasma grating in front of the solid target. Compared with that for a common flat target, hot electrons can be effectively heated with the well-designed grating size, leading to a stronger magnetic field. The spatial distribution of magnetic fields can be modulated by optimizing the grating period and height as well as the incident angle of the laser pulse.

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Diagnosing ratio of electron density to collision frequency of plasma surrounding scaled model in a shock tube using low-frequency alternating magnetic field phase shift Ming-Xing Wu(吴明兴), Kai Xie(谢楷), Yan Liu(刘艳), Han Xu(徐晗), Bao Zhang(张宝), and De-Yang Tian(田得阳) Chin. Phys. B, 2024, 33 (5):  055204.  DOI: 10.1088/1674-1056/ad2d56 Abstract ( 91 )   HTML ( 0 )   PDF (1229KB) ( 80 )   A non-contact low-frequency (LF) method of diagnosing the plasma surrounding a scaled model in a shock tube is proposed. This method utilizes the phase shift occurring after the transmission of an LF alternating magnetic field through the plasma to directly measure the ratio of the plasma loop average electron density to collision frequency. An equivalent circuit model is used to analyze the relationship of the phase shift of the magnetic field component of LF electromagnetic waves with the plasma electron density and collision frequency. The applicable range of the LF method on a given plasma scale is analyzed. The upper diagnostic limit for the ratio of the electron density (unit: m$^{-3}$) to collision frequency (unit: Hz) exceeds $1 \times 10^{11}$, enabling an electron density to exceed $1 \times 10^{20}$ m$^{-3}$ and a collision frequency to be less than 1 GHz. In this work, the feasibility of using the LF phase shift to implement the plasma diagnosis is also assessed. Diagnosis experiments on shock tube equipment are conducted by using both the electrostatic probe method and LF method. By comparing the diagnostic results of the two methods, the inversion results are relatively consistent with each other, thereby preliminarily verifying the feasibility of the LF method. The ratio of the electron density to the collision frequency has a relatively uniform distribution during the plasma stabilization. The LF diagnostic path is a loop around the model, which is suitable for diagnosing the plasma that surrounds the model. Finally, the causes of diagnostic discrepancy between the two methods are analyzed. The proposed method provides a new avenue for diagnosing high-density enveloping plasma.

CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES

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Theory and verification of moiré fringes for x-ray three-phase grating interferometer Yu-Zheng Shan(单雨征), Yong-Shuai Ge(葛永帅), Jun Yang(杨君), Da-Yu Guo(郭大育), Xue-Bao Cai(蔡学宝), Xiao-Ke Liu(刘晓珂), Xiao-Wen Hou(侯晓文), and Jin-Chuan Guo(郭金川) Chin. Phys. B, 2024, 33 (5):  056101.  DOI: 10.1088/1674-1056/ad2bf5 Abstract ( 97 )   HTML ( 0 )   PDF (2285KB) ( 27 )   Dual-phase and three-phase grating x-ray interference is a promising new technique for grating-based x-ray differential phase contrast imaging. Dual-phase grating interferometers have been relatively completely studied and discussed. In this paper, the corresponding imaging fringe formula of the three-phase grating interferometer is provided. At the same time, the similarities and differences between the three-phase grating interferometer and the dual-phase grating interferometer are investigated and verified, and that the three-phase grating interferometer can produce large-period moiré fringes without using the analyzing grating is demonstrated experimentally. Finally, a simple method of designing three-phase grating and multi-grating imaging systems from geometric optics based on the thin-lens theory of gratings is presented. These theoretical formulas and experimental results provide optimization tools for designing three-phase grating interferometer systems.

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High-pressure study on calcium azide (Ca(N3)2): Bending of azide ions stabilizes the structure Xiaoxin Wu(武晓鑫), Yingjian Wang(王颖健), Siqi Li(李思琪), Juncheng Lv(吕俊呈), Jingshu Wang(王婧姝), Lihua Yang(杨丽华), Qi Zhang(张旗), Yanqing Liu(刘艳清), Junkai Zhang(张俊凯), and Hongsheng Jia(贾洪声) Chin. Phys. B, 2024, 33 (5):  056201.  DOI: 10.1088/1674-1056/ad2b53 Abstract ( 91 )   HTML ( 0 )   PDF (1767KB) ( 83 )   The high-pressure structure and elastic properties of calcium azide (Ca(N$_{3}$)$_{2}$) were investigated using in-situ high-pressure x-ray diffraction and Raman scattering up to 54 GPa and 19 GPa, respectively. The compressibility of Ca(N$_{3}$)$_{2}$ changed as the pressure increased, and no phase transition occurred within the pressure from ambient pressure up to 54 GPa. The measured zero-pressure bulk modulus of Ca(N$_{3}$)$_{2 }$ is higher than that of other alkali metal azides, due to differences in the ionic character of their metal-azide bonds. Using CASTEP, all vibration modes of Ca(N$_{3}$)$_{2}$ were accurately identified in the vibrational spectrum at ambient pressure. In the high-pressure vibration study, several external modes (ext.) and internal bending modes ($\nu _2$) of azide anions (N$_{3}^{-}$) softened up to $\sim 7$ GPa and then hardened beyond that pressure. This evidence is consistent with the variation observed in the $F_{\rm E}$-$f_{\rm E}$ data analyzed from the XRD result, where the slope of the curve changes at 7.1 GPa. The main behaviors under pressure are the alternating compression, rotation, and bending of N$_{3}^{-}$ ions. The bending behavior makes the structure of Ca(N$_{3}$)$_{2}$ more stable under pressure.

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Low-frequency hybridized excess vibrations of two-dimensional glasses Licun Fu(付立存), Yiming Zheng(郑一鸣), and Lijin Wang(王利近) Chin. Phys. B, 2024, 33 (5):  056401.  DOI: 10.1088/1674-1056/ad205e Abstract ( 79 )   HTML ( 0 )   PDF (809KB) ( 22 )   One hallmark of glasses is the existence of excess vibrational modes at low frequencies $\omega$ beyond Debye's prediction. Numerous studies suggest that understanding low-frequency excess vibrations could help gain insight into the anomalous mechanical and thermodynamic properties of glasses. However, there is still intensive debate as to the frequency dependence of the population of low-frequency excess vibrations. In particular, excess modes could hybridize with phonon-like modes and the density of hybridized excess modes has been reported to follow $D_{\rm exc}(\omega) \sim \omega^{2}$ in 2D glasses with an inverse power law potential. Yet, the universality of the quadratic scaling remains unknown, since recent work suggested that interaction potentials could influence the scaling of the vibrational spectrum. Here, we extend the universality of the quadratic scaling for hybridized excess modes in 2D to glasses with potentials ranging from the purely repulsive soft-core interaction to the hard-core one with both repulsion and attraction as well as to glasses with significant differences in density or interparticle repulsion. Moreover, we observe that the number of hybridized excess modes exhibits a decrease in glasses with higher density or steeper interparticle repulsion, which is accompanied by a suppression of the strength of the sound attenuation. Our results indicate that the density bears some resemblance to the repulsive steepness of the interaction in influencing low-frequency properties.

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Enhanced superelasticity and reversible elastocaloric effect in nano-grained NiTi alloys with low stress hysteresis Min Zhou(周敏), Wei Wang(王维), Haojian Su(苏浩健), Zhongjun Hu(胡忠军), and Laifeng Li(李来风) Chin. Phys. B, 2024, 33 (5):  056501.  DOI: 10.1088/1674-1056/ad2a75 Abstract ( 133 )   HTML ( 0 )   PDF (1771KB) ( 79 )   Solid-state cooling technologies have been considered as potential alternatives for vapor compression cooling systems. The search for refrigeration materials displaying a unique combination of pronounced caloric effect, low hysteresis, and high reversibility on phase transformation was very active in recent years. Here, we achieved increase in the elastocaloric reversibility and decrease in the friction dissipation of martensite transformations in the superelastic nano-grained NiTi alloys obtained by cold rolling and annealing treatment, with very low stress hysteresis (6.3 MPa) under a large applied strain (5%). Large adiabatic temperature changes ($\Delta T_{\rm max}=16.3$ K at $\varepsilon =5$%) and moderate COP$_{\rm mater}$ values (maximum COP$_{\rm mater}=11.8$ at $\varepsilon =2$%) were achieved. The present nano-grained NiTi alloys exhibited great potential for applications as a highly efficient elastocaloric material.

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Coupling of quasi-localized and phonon modes in glasses at low frequency Jun Duan(段军), Song-Lin Cai(蔡松林), Gan Ding(丁淦), Lan-Hong Dai(戴兰宏), and Min-Qiang Jiang(蒋敏强) Chin. Phys. B, 2024, 33 (5):  056502.  DOI: 10.1088/1674-1056/ad2dce Abstract ( 93 )   HTML ( 0 )   PDF (3896KB) ( 52 )   Boson peak of glasses, a THz vibrational excess compared to Debye squared-frequency law, remains mysterious in condensed-matter physics and material science. It appears in many different kinds of glassy matters and is also argued to exist in damped crystals. A consensus is that boson peak originates from the coupling of the (quasi)-localized non-phonon modes and the plane-wave-like phonon modes, but the coupling behavior is still not fully understood. In this paper, by modulating the content of localized modes and the frequencies of phonon modes, the coupling is clearly reflected in the localization and anharmonicity of low-frequency vibrational modes. The coupling enhances with increasing cooling rate and sample size. For finite sample size, phonon modes do not fully intrude into the low frequency to form a dense spectrum and they are not sufficiently coupled to the localized modes, thus there is no Debye level and boson peak is ill-defined. This suggestion remains valid in the presence of thermal motions induced by temperature, even though the anharmonicity comes into play. Our results point to the coupling of quasi-localized and phonon modes and its relation to the boson peak.

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES

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Investigation of helicity-dependent photocurrent of surface states in (Bi0.7Sb0.3)2Te3 nanoplate Qin Yu(喻钦), Jinling Yu(俞金玲), Yonghai Chen(陈涌海), Yunfeng Lai(赖云锋), Shuying Cheng(程树英), and Ke He(何珂) Chin. Phys. B, 2024, 33 (5):  057101.  DOI: 10.1088/1674-1056/ad322c Abstract ( 77 )   HTML ( 0 )   PDF (1429KB) ( 78 )   Helicity-dependent photocurrent (HDPC) of the surface states in a high-quality topological insulator (Bi$_{0.7}$Sb$_{0.3}$)$_2$Te$_3$ nanoplate grown by chemical vapor deposition (CVD) is investigated. By investigating the angle-dependent HDPC, it is found that the HDPC is mainly contributed by the circular photogalvanic effect (CPGE) current when the incident plane is perpendicular to the connection of the two contacts, whereas the circular photon drag effect (CPDE) dominates the HDPC when the incident plane is parallel to the connection of the two contacts. In addition, the CPGE of the (Bi$_{0.7}$Sb$_{0.3}$)$_2$Te$_3$ nanoplate is regulated by temperature, light power, excitation wavelength, the source-drain and ionic liquid top-gate voltages, and the regulation mechanisms are discussed. It is demonstrated that (Bi$_{0.7}$Sb$_{0.3}$)$_2$Te$_3$ nanoplates may provide a good platform for novel opto-spintronics devices.

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Rational design and synthesis of Cr1-xTe/Ag2Te composites for solid-state thermoelectromagnetic cooling near room temperature Xiaochen Sun(孙笑晨), Chenghao Xie(谢承昊), Sihan Chen(陈思汗), Jingwei Wan(万京伟), Gangjian Tan(谭刚健), and Xinfeng Tang(唐新峰) Chin. Phys. B, 2024, 33 (5):  057201.  DOI: 10.1088/1674-1056/ad2d57 Abstract ( 83 )   HTML ( 1 )   PDF (1270KB) ( 109 )   Materials with both large magnetocaloric response and high thermoelectric performance are of vital importance for all-solid-state thermoelectromagnetic cooling. These two properties, however, hardly coexist in single phase materials except previously reported hexagonal Cr$_{1-x}$Te half metal where a relatively high magnetic entropy change $(-\Delta S_{\rm M})$ of $\sim 2.4 $ J$\cdot $kg$^{-1}\cdot$K$^{-1}$ @ 5 T and a moderate thermoelectric figure of merit (ZT) of $\sim 1.2\times 10^{-2}$ @ 300 K are simultaneously recorded. Herein we aim to increase the thermoelectric performance of Cr$_{1-x}$Te by compositing with semiconducting Ag$_{2}$Te. It is discovered that the in-situ synthesis of Cr$_{1-x}$Te/Ag$_{2}$Te composites by reacting their constitute elements above melting temperatures is unsuccessful because of strong phase competition. Specifically, at elevated temperatures ($T > 800 $ K), Cr$_{1-x}$Te has a much lower deformation energy than Ag$_{2}$Te and tends to become more Cr-deficient by capturing Te from Ag$_{2}$Te. Therefore, Ag is insufficiently reacted and as a metal it deteriorates ZT. We then rationalize the synthesis of Cr$_{1-x}$Te/Ag$_{2}$Te composites by ex-situ mix of the pre-prepared Cr$_{1-x}$Te and Ag$_{2}$Te binary compounds followed by densification at a low sintering temperature of 573 K under a pressure of 3.5 GPa. We show that by compositing with 7 mol% Ag$_{2}$Te, the Seebeck coefficient of Cr$_{1-x}$Te is largely increased while the lattice thermal conductivity is considerably reduced, leading to 72% improvement of ZT. By comparison, $-\Delta S_{\rm M}$ is only slightly reduced by 10% in the composite. Our work demonstrates the potential of Cr$_{1-x}$Te/Ag$_{2}$Te composites for thermoelectromagnetic cooling.

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Manipulation of internal blockage in triangular triple quantum dot Yue Qi(齐月) and Jian-Hua Wei(魏建华) Chin. Phys. B, 2024, 33 (5):  057301.  DOI: 10.1088/1674-1056/ad2d54 Abstract ( 102 )   HTML ( 0 )   PDF (669KB) ( 19 )   We utilize the calculation of hierarchical equations of motion to demonstrate that the spin-dependent properties between adjacent quantum dots (QDs) can be changed by breaking the internal symmetry configuration, corresponding to the inversion of dominant chiral states. In the linear triple quantum dots (LTQDs) connected to two electron reservoirs, we can observe that the blockage appears at the triangle triple quantum dots (TTQDs) by gradually increasing the coupling strength between next-nearest double QDs. When the initial coupling between LTQDs has altered, the internal chiral circulation also undergoes the corresponding transform, thus achieving qualitative regulation and detection of the blocking region. We also investigate the response of the chiral circulation to the dot-lead coupling strength, indicating the overall robust chiral circulation of the TTQDs frustration.

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Effect of strain on structure and electronic properties of monolayer C4N4 Hao Chen(陈昊), Ying Xu(徐瑛), Jia-Shi Zhao(赵家石), and Dan Zhou(周丹) Chin. Phys. B, 2024, 33 (5):  057302.  DOI: 10.1088/1674-1056/ad260c Abstract ( 102 )   HTML ( 0 )   PDF (1160KB) ( 31 )   The first-principles calculations are performed to examine structural, mechanical, and electronic properties at large strain for a monolayer C$_{4}$N$_{4}$, which has been predicted as an anchoring promising material to attenuate shuttle effect in Li-S batteries stemming from its large absorption energy and low diffusion energy barrier. Our results show that the ideal strengths of C$_{4}$N$_{4}$ under tension and pure shear deformation conditions reach 13.9 GPa and 12.5 GPa when the strains are 0.07 and 0.28, respectively. The folded five-membered rings and diverse bonding modes between carbon and nitrogen atoms enhance the ability to resist plastic deformation of C$_{4}$N$_{4}$. The orderly bond-rearranging behaviors under the weak tensile loading path along the [100] direction cause the impressive semiconductor-metal transition and inverse semiconductor-metal transition. The present results enrich the knowledge of the structure and electronic properties of C$_{4}$N$_{4}$ under deformations and shed light on exploring other two-dimensional materials under diverse loading conditions.

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Magnetic and magnetocaloric effect of Er20Ho20Dy20Cu20Ni20 high-entropy metallic glass Shi-Lin Yu(于世霖), Lu Tian(田路), Jun-Feng Wang(王俊峰), Xin-Guo Zhao(赵新国), Da Li(李达), Zhao-Jun Mo(莫兆军), and Bing Li(李昺) Chin. Phys. B, 2024, 33 (5):  057502.  DOI: 10.1088/1674-1056/ad1a94 Abstract ( 113 )   HTML ( 0 )   PDF (748KB) ( 95 )   Er$_{20}$Ho$_{20}$Dy$_{20}$Cu$_{20}$Ni$_{20}$ high-entropy metallic glass exhibited excellent magnetic refrigeration material with a wide temperature range and high refrigeration capacity (RC) was reported. Er$_{20}$Ho$_{20}$Dy$_{20}$Cu$_{20}$Ni$_{20}$ high-entropy metallic glass was observed with typical spin glass behavior around 15.5 K. In addition, we find that the magnetic entropy change ($-\Delta S_{\rm M}$) originates from the sample undergoing a ferromagnetic (FM) to paramagnetic (PM) transition around 20 K. Under a field change from 0 T to 7 T, the value of maximum magnetic entropy change ($-\Delta S_{\rm M}^{\max}$) reaches 12.5 J/kg$\cdot$K, and the corresponding value of RC reaches 487.7 J/kg in the temperature range from 6 K to 60 K. The large RC and wide temperature range make the Er$_{20}$Ho$_{20}$Dy$_{20}$Cu$_{20}$Ni$_{20}$ high-entropy metallic glass be a promising material for application in magnetic refrigerators.

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Structure, ferroelectric, and enhanced fatigue properties of sol-gel-processed new Bi-based perovskite thin films of Bi(Cu1/2Ti1/2)O3-PbTiO3 Wei-Bin Song(宋伟宾), Guo-Qiang Xi(席国强), Zhao Pan(潘昭), Jin Liu(刘锦), Xu-Bin Ye(叶旭斌), Zhe-Hong Liu(刘哲宏), Xiao Wang(王潇), Peng-Fei Shan(单鹏飞), Lin-Xing Zhang(张林兴), Nian-Peng Lu(鲁年鹏), Long-Long Fan(樊龙龙), Xiao-Mei Qin(秦晓梅), and You-Wen Long(龙有文) Chin. Phys. B, 2024, 33 (5):  057701.  DOI: 10.1088/1674-1056/ad2a71 Abstract ( 100 )   HTML ( 0 )   PDF (2037KB) ( 51 )   Bi-based perovskite ferroelectric thin films have wide applications in electronic devices due to their excellent ferroelectric properties. New Bi-based perovskite thin films Bi(Cu$_{1/2}$Ti$_{1/2}$)O$_{3}$-PbTiO$_{3}$ (BCT-PT) are deposited on Pt(111)/Ti/SiO$_{2}$/Si substrates in the present study by the traditional sol-gel method. Their structures and related ferroelectric and fatigue characteristics are studied in-depth. The BCT-PT thin films exhibit good crystallization within the phase-pure perovskite structure, besides, they have a predominant (100) orientation together with a dense and homogeneous microstructure. The remnant polarization (2$P_{\rm r}$) values at 30 μC/cm$^{2}$ and 16 μC/cm$^{2}$ are observed in 0.1BCT-0.9PT and 0.2BCT-0.8PT thin films, respectively. More intriguingly, although the polarization values are not so high, 0.2BCT-0.8PT thin films show outstanding polarization fatigue properties, with a high switchable polarization of 93.6% of the starting values after 10$^{8}$ cycles, indicating promising applications in ferroelectric memories.

INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY

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Regulating the dopant clustering in LiZnAs-based diluted magnetic semiconductor Zihang Jia(贾子航), Bo Zhou(周波), Zhenyi Jiang(姜振益), and Xiaodong Zhang(张小东) Chin. Phys. B, 2024, 33 (5):  058101.  DOI: 10.1088/1674-1056/ad3034 Abstract ( 88 )   HTML ( 0 )   PDF (770KB) ( 58 )   Tuning of the magnetic interaction plays the vital role in reducing the clustering of magnetic dopant in diluted magnetic semiconductors (DMS). Due to the not well understood magnetic mechanism and the interplay between different magnetic mechanisms, no efficient and universal tuning strategy is proposed at present. Here, the magnetic interactions and formation energies of isovalent-doped (Mn) and aliovalent (Cr)-doped LiZnAs are studied based on density functional theory (DFT). It is found that the dopant-dopant distance-dependent magnetic interaction is highly sensitive to the carrier concentration and carrier type and can only be explained by the interplay between two magnetic mechanisms, i.e., super-exchange and Zener's p-d exchange model. Thus, the magnetic behavior and clustering of magnetic dopant can be tuned by the interplay between two magnetic mechanisms. The insensitivity of the tuning effect to $U$ parameter suggests that our strategy could be universal to other DMS.

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Atomistic understanding of capacity loss in LiNiO2 for high-nickel Li-ion batteries: First-principles study Shuai Peng(彭率), Li-Juan Chen(陈丽娟), Chang-Chun He(何长春), and Xiao-Bao Yang(杨小宝) Chin. Phys. B, 2024, 33 (5):  058201.  DOI: 10.1088/1674-1056/ad2a72 Abstract ( 86 )   HTML ( 0 )   PDF (1870KB) ( 49 )   Combining the first-principles calculations and structural enumeration with recognition, the delithiation process of LiNiO$_{2}$ is investigated, where various supercell shapes are considered in order to obtain the formation energy of Li$_{x}$NiO$_{2}$. Meanwhile, the voltage profile is simulated and the ordered phases of lithium vacancies corresponding to concentrations of 1/4, 2/5, 3/7, 1/2, 2/3, 3/4, 5/6, and 6/7 are predicted. To understand the capacity decay in the experiment during the charge/discharge cycles, deoxygenation and Li/Ni antisite defects are calculated, revealing that the chains of oxygen vacancies will be energetically preferrable. It can be inferred that in the absence of oxygen atom in high delithiate state, the diffusion of Ni atoms is facilitated and the formation of Li/Ni antisite is induced.

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Accurate estimation of Li/Ni mixing degree of lithium nickel oxide cathode materials Penghao Chen(陈鹏浩), Lei Xu(徐磊), Xiqian Yu(禹习谦), and Hong Li(李泓) Chin. Phys. B, 2024, 33 (5):  058202.  DOI: 10.1088/1674-1056/ad3036 Abstract ( 111 )   HTML ( 0 )   PDF (3662KB) ( 63 )   Li/Ni mixing negatively influences the discharge capacity of lithium nickel oxide and high-nickel ternary cathode materials. However, accurately measuring the Li/Ni mixing degree is difficult due to the preferred orientation of lab-based XRD measurements using Bragg-Brentano geometry. Here, we find that employing spherical harmonics in Rietveld refinement to eliminate the preferred orientation can significantly decrease the measurement error of the Li/Ni mixing ratio. The Li/Ni mixing ratio obtained from Rietveld refinement with spherical harmonics shows a strong correlation with discharge capacity, which means the electrochemical capacity of lithium nickel oxide and high-nickel ternary cathode can be estimated by the Li/Ni mixing degree. Our findings provide a simple and accurate method to estimate the Li/Ni mixing degree, which is valuable to the structural analysis and screening of the synthesis conditions of lithium nickel oxide and high-nickel ternary cathode materials.

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A novel order-reduced thermal-coupling electrochemical model for lithium-ion batteries Yizhan Xie(谢奕展), Shuhui Wang(王舒慧), Zhenpo Wang(王震坡), and Ximing Cheng(程夕明) Chin. Phys. B, 2024, 33 (5):  058203.  DOI: 10.1088/1674-1056/ad1f52 Abstract ( 87 )   HTML ( 0 )   PDF (3734KB) ( 53 )   Although the single-particle model enhanced with electrolyte dynamics (SPMe) is simplified from the pseudo-two-dimensional (P2D) electrochemical model for lithium-ion batteries, it is difficult to solve the partial differential equations of solid-liquid phases in real-time applications. Moreover, working temperatures have a heavy impact on the battery behavior. Hence, a thermal-coupling SPMe is constructed. Herein, a lumped thermal model is established to estimate battery temperatures. The order of the SPMe model is reduced by using both transfer functions and truncation techniques and merged with Arrhenius equations for thermal effects. The polarization voltage drop is then modified through the use of test data because its original model is unreliable theoretically. Finally, the coupling-model parameters are extracted using genetic algorithms. Experimental results demonstrate that the proposed model produces average errors of about 42 mV under 15 constant current conditions and 15 mV under nine dynamic conditions, respectively. This new electrochemical-thermal coupling model is reliable and expected to be used for onboard applications.

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Individual dynamics and local heterogeneity provide a microscopic view of the epidemic spreading Youyuan Zhu(朱友源), Ruizhe Shen(沈瑞哲), Hao Dong(董昊), and Wei Wang(王炜) Chin. Phys. B, 2024, 33 (5):  058301.  DOI: 10.1088/1674-1056/ad1a90 Abstract ( 98 )   HTML ( 0 )   PDF (2619KB) ( 103 )   The COVID-19 pandemic has caused severe global disasters, highlighting the importance of understanding the details and trends of epidemic transmission in order to introduce efficient intervention measures. While the widely used deterministic compartmental models have qualitatively presented continuous "analytical" insight and captured some transmission features, their treatment usually lacks spatiotemporal variation. Here, we propose a stochastic individual dynamical (SID) model to mimic the random and heterogeneous nature of epidemic propagation. The SID model provides a unifying framework for representing the spatiotemporal variations of epidemic development by tracking the movements of each individual. Using this model, we reproduce the infection curves for COVID-19 cases in different areas globally and find the local dynamics and heterogeneity at the individual level that affect the disease outbreak. The macroscopic trend of virus spreading is clearly illustrated from the microscopic perspective, enabling a quantitative assessment of different interventions. Seemingly, this model is also applicable to studying stochastic processes at the ``meter scale", e.g., human society's collective dynamics.

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A novel complex-high-order graph convolutional network paradigm: ChyGCN He-Xiang Zheng(郑和翔), Shu-Yu Miao(苗书宇), and Chang-Gui Gu(顾长贵) Chin. Phys. B, 2024, 33 (5):  058401.  DOI: 10.1088/1674-1056/ad20db Abstract ( 85 )   HTML ( 0 )   PDF (607KB) ( 21 )   In recent years, there has been a growing interest in graph convolutional networks (GCN). However, existing GCN and variants are predominantly based on simple graph or hypergraph structures, which restricts their ability to handle complex data correlations in practical applications. These limitations stem from the difficulty in establishing multiple hierarchies and acquiring adaptive weights for each of them. To address this issue, this paper introduces the latest concept of complex hypergraphs and constructs a versatile high-order multi-level data correlation model. This model is realized by establishing a three-tier structure of complexes-hypergraphs-vertices. Specifically, we start by establishing hyperedge clusters on a foundational network, utilizing a second-order hypergraph structure to depict potential correlations. For this second-order structure, truncation methods are used to assess and generate a three-layer composite structure. During the construction of the composite structure, an adaptive learning strategy is implemented to merge correlations across different levels. We evaluate this model on several popular datasets and compare it with recent state-of-the-art methods. The comprehensive assessment results demonstrate that the proposed model surpasses the existing methods, particularly in modeling implicit data correlations (the classification accuracy of nodes on five public datasets Cora, Citeseer, Pubmed, Github Web ML, and Facebook are 86.1$\pm $0.33, 79.2$\pm $0.35, 83.1$\pm $0.46, 83.8$\pm $0.23, and 80.1$\pm $0.37, respectively). This indicates that our approach possesses advantages in handling datasets with implicit multi-level structures.

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Tunable superconducting resonators via on-chip control of local magnetic field Chen-Guang Wang(王晨光), Wen-Cheng Yue(岳文诚), Xuecou Tu(涂学凑), Tianyuan Chi(迟天圆), Tingting Guo(郭婷婷), Yang-Yang Lyu(吕阳阳), Sining Dong(董思宁), Chunhai Cao(曹春海), Labao Zhang(张蜡宝), Xiaoqing Jia(贾小氢), Guozhu Sun(孙国柱), Lin Kang(康琳), Jian Chen(陈健), Yong-Lei Wang(王永磊), Huabing Wang(王华兵), and Peiheng Wu(吴培亨) Chin. Phys. B, 2024, 33 (5):  058402.  DOI: 10.1088/1674-1056/ad2f21 Abstract ( 96 )   HTML ( 1 )   PDF (1293KB) ( 64 )   Superconducting microwave resonators play a pivotal role in superconducting quantum circuits. The ability to fine-tune their resonant frequencies provides enhanced control and flexibility. Here, we introduce a frequency-tunable superconducting coplanar waveguide resonator. By applying electrical currents through specifically designed ground wires, we achieve the generation and control of a localized magnetic field on the central line of the resonator, enabling continuous tuning of its resonant frequency. We demonstrate a frequency tuning range of 54.85 MHz in a 6.21-GHz resonator. This integrated and tunable resonator holds great potential as a dynamically tunable filter and as a key component of communication buses and memory elements in superconducting quantum computing.

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Terahertz high-sensitivity SIS mixer based on Nb-AlN-NbN hybrid superconducting tunnel junctions Bo-Liang Liu(刘博梁), Dong Liu(刘冬), Ming Yao(姚明), Jun-Da Jin(金骏达), Zheng Wang(王争), Jing Li(李婧), Sheng-Cai Shi(史生才), Artem Chekushkin, Michael Fominsky, Lyudmila Filippenko, and Valery Koshelets Chin. Phys. B, 2024, 33 (5):  058501.  DOI: 10.1088/1674-1056/ad2bf7 Abstract ( 92 )   HTML ( 0 )   PDF (1750KB) ( 58 )   The terahertz band, a unique segment of the electromagnetic spectrum, is crucial for observing the cold, dark universe and plays a pivotal role in cutting-edge scientific research, including the study of cosmic environments that support life and imaging black holes. High-sensitivity superconductor-insulator-superconductor (SIS) mixers are essential detectors for terahertz astronomical telescopes and interferometric arrays. Compared to the commonly used classical Nb/AlOx/Nb superconducting tunnel junction, the Nb/AlN/NbN hybrid superconducting tunnel junction has a higher energy gap voltage and can achieve a higher critical current density. This makes it particularly promising for the development of ultra-wideband, high-sensitivity coherent detectors or mixers in various scientific research fields. In this paper, we present a superconducting SIS mixer based on Nb/AlN/NbN parallel-connected twin junctions (PCTJ), which has a bandwidth extending up to 490 GHz-720 GHz. The best achieved double-sideband (DSB) noise temperature (sensitivity) is below three times the quantum noise level.

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Influence of exchange bias on spin torque ferromagnetic resonance for quantification of spin-orbit torque efficiency Qian Zhao(赵乾), Tengfei Zhang(张腾飞), Bin He(何斌), Zimu Li(李子木), Senfu Zhang(张森富), Guoqiang Yu(于国强), Jianbo Wang(王建波), Qingfang Liu(刘青芳), and Jinwu Wei(魏晋武) Chin. Phys. B, 2024, 33 (5):  058502.  DOI: 10.1088/1674-1056/ad2d55 Abstract ( 78 )   HTML ( 0 )   PDF (881KB) ( 105 )   Antiferromagnet (AFM)/ferromagnet (FM) heterostructure is a popular system for studying the spin-orbit torque (SOT) of AFMs. However, the interfacial exchange bias field induces that the magnetization in FM layer is noncollinear to the external magnetic field, namely the magnetic moment drag effect, which further influences the characteristic of SOT efficiency. In this work, we study the SOT efficiencies of IrMn/NiFe bilayers with strong interfacial exchange bias by using spin-torque ferromagnetic resonance (ST-FMR) method. A full analysis on the AFM/FM systems with exchange bias is performed, and the angular dependence of magnetization on external magnetic field is determined through the minimum rule of free energy. The ST-FMR results can be well fitted by this model. We obtained the relative accurate SOT efficiency $\xi_{\rm DL} = 0.058$ for the IrMn film. This work provides a useful method to analyze the angular dependence of ST-FMR results and facilitates the accurate measurement of SOT efficiency for the AFM/FM heterostructures with strong exchange bias.

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Cholesterol-induced deformation of the gramicidin A channel inhibiting potassium ion binding and transport Pan Xiao(肖盼), Yu Cao(曹宇), Jin Zhu(朱瑾), and Qing Liang(梁清) Chin. Phys. B, 2024, 33 (5):  058701.  DOI: 10.1088/1674-1056/ad334e Abstract ( 78 )   HTML ( 0 )   PDF (1756KB) ( 80 )   Gramicidin A (gA) is a kind of antibiotic peptide produced by bacillus brevis and it can dimerize across lipid bilayers to form a monovalent cation channel. In this work, we investigate the impact of cholesterol in the lipid bilayer on the binding of potassium ions with the gA channel and the transport of the ions across the channel. The results indicate that cholesterol can significantly influence the conformational stability of the gA channel and cause the channel deformation which inhibits the potassium ion binding with the channel and transport across the channel. The work provides some molecular insights into understanding of influence of lipids on the activity of gA channel in both model membranes and plasma membranes of intact cells.

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In situ luminescence measurements of GaN/Al2O3 film under different energy proton irradiations Wenli Jiang(蒋文丽), Xiao Ouyang(欧阳潇), Menglin Qiu(仇猛淋), Minju Ying(英敏菊), Lin Chen(陈琳), Pan Pang(庞盼), Chunlei Zhang(张春雷), Yaofeng Zhang(张耀锋), and Bin Liao(廖斌) Chin. Phys. B, 2024, 33 (5):  058702.  DOI: 10.1088/1674-1056/ad1b3f Abstract ( 69 )   HTML ( 0 )   PDF (1414KB) ( 15 )   Ion beam-induced luminescence (IBIL) experiments were performed to investigate the in situ luminescence of GaN/Al$_{2}$O$_{3}$ at varying ion energies, which allowed for the measurement of defects at different depths within the material. The energies of H$^{+}$ were set to 500 keV, 640 keV and 2 MeV, the Bragg peaks of which correspond to the GaN film, GaN/Al$_{2}$O$_{3}$ heterojunction and Al$_{2}$O$_{3}$ substrate, respectively. A photoluminescence measurement at 250 K was also performed for comparison, during which only near band edge (NBE) and yellow band luminescence in the GaN film were observed. The evolution of the luminescence of the NBE and yellow band in the GaN film was discussed, and both exhibited a decrease with the fluence of H$^{+}$. Additionally, the luminescence of F centers, induced by oxygen vacancies, and Cr$^{3+}$, resulting from the $^{2}$E$\,\to^{4}$A$_{2}$ radiative transition in Al$_{2}$O$_{3}$, were measured using 2 MeV H$^{+}$. The luminescence intensity of F centers increases gradually with the fluence of H$^{+}$. The luminescence evolution of Cr$^{3+}$ is consistent with a yellow band center, attributed to its weak intensity, and it is situated within the emission band of the yellow band in the GaN film. Our results show that IBIL measurement can effectively detect the luminescence behavior of multilayer films by adjusting the ion energy. Luminescence measurement can be excited by various techniques, but IBIL can satisfy in situ luminescence measurement, and multilayer structural materials of tens of micrometers can be measured through IBIL by adjusting the energy of the inducing ions. The evolution of defects at different layers with ion fluence can be obtained.

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Analysis of the optimal target node to reduce seizure-like discharge in networks Luyao Yan(闫璐瑶), Honghui Zhang(张红慧), and Zhongkui Sun(孙中奎) Chin. Phys. B, 2024, 33 (5):  058703.  DOI: 10.1088/1674-1056/ad3346 Abstract ( 83 )   HTML ( 1 )   PDF (1284KB) ( 67 )   Network approaches have been widely accepted to guide surgical strategy and predict outcome for epilepsy treatment. This study starts with a single oscillator to explore brain activity, using a phenomenological model capable of describing healthy and epileptic states. The ictal number of seizures decreases or remains unchanged with increasing the speed of oscillator excitability and in each seizure, there is an increasing tendency for ictal duration with respect to the speed. The underlying reason is that the strong excitability speed is conducive to reduce transition behaviors between two attractor basins. Moreover, the selection of the optimal removal node is estimated by an indicator proposed in this study. Results show that when the indicator is less than the threshold, removing the driving node is more possible to reduce seizures significantly, while the indicator exceeds the threshold, the epileptic node could be the removal one. Furthermore, the driving node is such a potential target that stimulating it is obviously effective in suppressing seizure-like activity compared to other nodes, and the propensity of seizures can be reduced 60$%$ with the increased stimulus strength. Our results could provide new therapeutic ideas for epilepsy surgery and neuromodulation.

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Synchronization and firing mode transition of two neurons in a bilateral auditory system driven by a high-low frequency signal Charles Omotomide Apata, Yi-Rui Tang(唐浥瑞), Yi-Fan Zhou(周祎凡), Long Jiang(蒋龙), and Qi-Ming Pei(裴启明) Chin. Phys. B, 2024, 33 (5):  058704.  DOI: 10.1088/1674-1056/ad1a8e Abstract ( 121 )   HTML ( 1 )   PDF (7642KB) ( 31 )   The FitzHugh-Nagumo neuron circuit integrates a piezoelectric ceramic to form a piezoelectric sensing neuron, which can capture external sound signals and simulate the auditory neuron system. Two piezoelectric sensing neurons are coupled by a parallel circuit consisting of a Josephson junction and a linear resistor, and a binaural auditory system is established. Considering the non-singleness of external sound sources, the high-low frequency signal is used as the input signal to study the firing mode transition and synchronization of this system. It is found that the angular frequency of the high-low frequency signal is a key factor in determining whether the dynamic behaviors of two coupled neurons are synchronous. When they are in synchronization at a specific angular frequency, the changes in physical parameters of the input signal and the coupling strength between them will not destroy their synchronization. In addition, the firing mode of two coupled auditory neurons in synchronization is affected by the characteristic parameters of the high-low frequency signal rather than the coupling strength. The asynchronous dynamic behavior and variations in firing modes will harm the auditory system. These findings could help determine the causes of hearing loss and devise functional assistive devices for patients.

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Effects of individual heterogeneity on social contagions Fu-Zhong Nian(年福忠) and Yu Yang(杨宇) Chin. Phys. B, 2024, 33 (5):  058705.  DOI: 10.1088/1674-1056/ad225e Abstract ( 71 )   HTML ( 0 )   PDF (11073KB) ( 64 )   Despite having significant effects on social contagions, individual heterogeneity has frequently been overlooked in earlier studies. To better understand the complexity of social contagions, a non-Markovian model incorporating heterogeneous social influence and adoption thresholds is introduced. For theoretical analysis, a generalized edge-based compartmental theory which considers the heterogeneities of social influence and adoption thresholds is developed. Focusing on the final adoption size, the critical propagation probability, and the phase transition type, social contagions for adoption thresholds that follow normal distributions with various standard deviations, follow various distributions, and correlate with degrees are investigated. When thresholds follow normal distributions, a larger standard deviation results in a larger final adoption size when the information propagation probability is relatively low. However, when the information propagation probability is relatively high, a larger standard deviation results in a smaller final adoption size. When thresholds follow various distributions, crossover phenomena in phase transition are observed when investigating the relationship of the final adoption size versus the average adoption threshold for some threshold distributions. When thresholds are correlated with degrees, similar crossover phenomena occur when investigating the relationship of the final adoption size versus the degree correlation index. Additionally, we find that increasing the heterogeneity of social influence suppresses the effects of adoption threshold heterogeneity on social contagions in three cases. Our theory predictions agree well with the simulation results.

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Estimation of cancer cell migration in biomimetic random/oriented collagen fiber microenvironments Hot! Jingru Yao(姚静如), Guoqiang Li(李国强), Xiyao Yao(姚喜耀), Lianjie Zhou(周连杰), Zhikai Ye(叶志凯), Yanping Liu(刘艳平), Dongtian Zheng(郑栋天), Ting Tang(唐婷), Kena Song(宋克纳), Guo Chen(陈果), and Liyu Liu(刘雳宇) Chin. Phys. B, 2024, 33 (5):  058706.  DOI: 10.1088/1674-1056/ad334c Abstract ( 144 )   HTML ( 5 )   PDF (3033KB) ( 209 )   Increasing data indicate that cancer cell migration is regulated by extracellular matrixes and their surrounding biochemical microenvironment, playing a crucial role in pathological processes such as tumor invasion and metastasis. However, conventional two-dimensional cell culture and animal models have limitations in studying the influence of tumor microenvironment on cancer cell migration. Fortunately, the further development of microfluidic technology has provided solutions for the study of such questions. We utilize microfluidic chip to build a random collagen fiber microenvironment (RFM) model and an oriented collagen fiber microenvironment (OFM) model that resemble early stage and late stage breast cancer microenvironments, respectively. By combining cell culture, biochemical concentration gradient construction, and microscopic imaging techniques, we investigate the impact of different collagen fiber biochemical microenvironments on the migration of breast cancer MDA-MB-231-RFP cells. The results show that MDA-MB-231-RFP cells migrate further in the OFM model compared to the RFM model, with significant differences observed. Furthermore, we establish concentration gradients of the anticancer drug paclitaxel in both the RFM and OFM models and find that paclitaxel significantly inhibits the migration of MDA-MB-231-RFP cells in the RFM model, with stronger inhibition on the high concentration side compared to the low concentration side. However, the inhibitory effect of paclitaxel on the migration of MDA-MB-231-RFP cells in the OFM model is weak. These findings suggest that the oriented collagen fiber microenvironment resembling the late-stage tumor microenvironment is more favorable for cancer cell migration and that the effectiveness of anticancer drugs is diminished. The RFM and OFM models constructed in this study not only provide a platform for studying the mechanism of cancer development, but also serve as a tool for the initial measurement of drug screening.

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Cooperative activation of sodium channels for downgrading the energy efficiency in neuronal information processing Haoran Yan(严浩然), Jiaqi Yan(颜家琦), Lianchun Yu(俞连春), and Yu-Feng Shao(邵玉峰) Chin. Phys. B, 2024, 33 (5):  058801.  DOI: 10.1088/1674-1056/ad21f5 Abstract ( 107 )   HTML ( 2 )   PDF (691KB) ( 62 )   The Hodgkin-Huxley model assumes independent ion channel activation, although mutual interactions are common in biological systems. This raises the problem why neurons would favor independent over cooperative channel activation. In this study, we evaluate how cooperative activation of sodium channels affects the neuron's information processing and energy consumption. Simulations of the stochastic Hodgkin-Huxley model with cooperative activation of sodium channels show that, while cooperative activation enhances neuronal information processing capacity, it greatly increases the neuron's energy consumption. As a result, cooperative activation of sodium channel degrades the energy efficiency for neuronal information processing. This discovery improves our understanding of the design principles for neural systems, and may provide insights into future designs of the neuromorphic computing devices as well as systematic understanding of pathological mechanisms for neural diseases.

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Identifying influential spreaders in complex networks based on density entropy and community structure Zhan Su(苏湛), Lei Chen(陈磊), Jun Ai(艾均), Yu-Yu Zheng(郑雨语), and Na Bie(别娜) Chin. Phys. B, 2024, 33 (5):  058901.  DOI: 10.1088/1674-1056/ad20d6 Abstract ( 147 )   HTML ( 0 )   PDF (2330KB) ( 90 )   In recent years, exploring the relationship between community structure and node centrality in complex networks has gained significant attention from researchers, given its fundamental theoretical significance and practical implications. To address the impact of network communities on target nodes and effectively identify highly influential nodes with strong propagation capabilities, this paper proposes a novel influential spreaders identification algorithm based on density entropy and community structure (DECS). The proposed method initially integrates a community detection algorithm to obtain the community partition results of the networks. It then comprehensively considers the internal and external density entropies and degree centrality of the target node to evaluate its influence. Experimental validation is conducted on eight networks of varying sizes through susceptible-infected-recovered (SIR) propagation experiments and network static attack experiments. The experimental results demonstrate that the proposed method outperforms five other node centrality methods under the same comparative conditions, particularly in terms of information spreading capability, thereby enhancing the accurate identification of critical nodes in networks.

CORRIGENDUM

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Corrigendum to "Absolute partial and total ionization cross sections of carbon monoxide with electron collision from 350eV to 8000eV" Taj Wali Khan, Weizhe Huang(黄伟哲), Enliang Wang(王恩亮), Xu Shan(单旭), and Xiangjun Chen(陈向军) Chin. Phys. B, 2024, 33 (5):  059901.  DOI: 10.1088/1674-1056/ad3efc Abstract ( 80 )   HTML ( 0 )   PDF (678KB) ( 23 )   The numbers of longitudinal axis in Fig. 1(a) of the paper [Chin. Phys. B 33 043401 (2024)] have been corrected. This modification does not affect the result presented in the paper.