Chin. Phys. B

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 ( 10 )

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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.

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 ( 12 )

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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.

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 ( 27 )

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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.

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 ( 33 )

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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.

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), Meng-Jun Hu(胡孟军)

Chin. Phys. B, 2024, 33 (5): 050302. DOI: 10.1088/1674-1056/ad18ab

Abstract ( 31 )

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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.

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 ( 13 )

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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.

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 ( 8 )

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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.

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 ( 6 )

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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 0th 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.

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 ( 4 )

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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.

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 ( 9 )

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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.

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 ( 13 )

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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.

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 ( 10 )

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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.

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 ( 18 )

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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.

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 ( 16 )

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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.

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 ( 45 )

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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.

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 ( 6 )

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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.

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 ( 7 )

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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.

TCAS-PINN: Physics-informed neural networks with a novel temporal causality-based adaptive sampling method

Jia Guo, Haifeng Wang, Shilin Gu, and Chenping Hou

Chin. Phys. B, 2024, 33 (5): 050701. DOI: 10.1088/1674-1056/ad21f3

Abstract ( 8 )

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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.

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 ( 24 )

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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 Δf_zeros, the dispersion signal has two positive maxima with an interval defined as the shoulder interval Δf_sho, which is theoretically expected to be used to measure a much weaker MW electric field. The relationship of the MW field strength E_MW and Δf_sho is experimentally studied at the MW frequencies of 31.6 GHz and 9.2 GHz respectively. The results show that Δf_sho can be used to characterize the much weaker E_MW than that of Δf_zeros and the traditional EIT—AT splitting interval Δf_m; the minimum E_MW measured by Δf_sho is about 30 times smaller than that by Δf_m. As an example, the minimum E_MW at 9.2 GHz that can be characterized by Δf_sho is 0.056 mV/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_MW measured by the spectral frequency interval, which is important in the direct measurement of weak E_MW.

A historical overview of nano-optics: From near-field optics toplasmonics

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 ( 3 )

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Nano-optics is an emergent research field in physics that appeared in the 1980s, which deals with light--matter optical interactions at the nanometerscale. In early studies of nano-optics, the main concern focus is to obtainhigher optical resolution over the diffraction limit. The researches ofnear-field imaging and spectroscopy based on scanning near-field opticalmicroscopy (SNOM) are developed. The exploration of improving SNOM probe fornear-field detection leads to the emergence of surface plasmons. In thesense of resolution and wider application, there has been a significanttransition from seeking higher resolution microscopy to plasmonic near-fieldmodulations in the nano-optics community during the nano-optic development.Nowadays, studies of nano-optics prefer the investigation of plasmonics indifferent material systems. In this article, the history of the developmentof near-field optics is briefly reviewed. The difficulties of conventionalSNOM to achieve higher resolution are discussed. As an alternative solution,surface plasmons have shown the advantages of higher resolution, widerapplication, and flexible nano-optical modulation for new devices. Thetypical studies in different periods are introduced and characteristics ofnano-optics in each stage are analyzed. In this way, the evolution progressfrom near-field optics to plasmonics of nano-optics research is presented.The future development of nano-optics is discussed then.

Literature classification and its applications in condensed matter physics and materials science by natural language processing

Siyuan Wu, Tiannian Zhu, Sijia Tu, Ruijuan Xiao, Jie Yuan, Quansheng Wu, Hong Li, and Hongming Weng

Chin. Phys. B, 2024, 33 (5): 050704. DOI: 10.1088/1674-1056/ad3c30

Abstract ( 11 )

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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.

FPGA and computer-vision-based atom tracking technology for scanning probe microscopy

Feng-Du Yu, Li Liu, Su-Ke Wang, Xin-Biao Zhang, Le Lei, Yuan-Zhi Huang, Rui-Song Ma, and Qing Huan

Chin. Phys. B, 2024, 33 (5): 050705. DOI: 10.1088/1674-1056/ad34cb

Abstract ( 17 )

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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.

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 ( 16 )

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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 Λ—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 1⁵Σ⁺ and 2⁵Σ⁺ 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.

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-FanZhu(朱林繁)

Chin. Phys. B, 2024, 33 (5): 053401. DOI: 10.1088/1674-1056/ad24d9

Abstract ( 8 )

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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.

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 ( 12 )

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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.

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 ( 13 )

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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).

Extending microwave-frequency electric-field detection through single transmission peak method

Qing 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 ( 137 )

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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.

Superradiance of ultracold cesium Rydberg |65D_5/2>→|66P_3/2>

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 ( 10 )

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We investigate Rydberg |65D_5/2>→|66P_3/2> superradiance in dense ultracold cesium atoms, where the ground atoms are excited to |65D_5/2> Rydberg states via two-photon excitation in a standard magneto-optical trap. The superradiant spectrum of |65D_5/2>→|66P_3/2> is obtained using the state-selective field ionization technique. We observe its dynamic evolution process by varying the delay time of ionization field t_d. The results show that the evolution process of |65D_5/2>→|66P_3/2> 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_e and principal quantum number n is investigated. The results show that the superradiance becomes faster with increasing N_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.

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 ( 14 )

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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 μ m to 20 μ m, 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.

A novel dual-channel thermo-optic locking method for the whisperinggallery mode microresonator

Wenjie Fan(范文杰), Wenyao Liu(刘文耀), ZiwenPan(潘梓文), Rong Wang(王蓉), Lai Liu(刘来), EnboXing(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 ( 4 )

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Mode locking can be effectively achieved by using the thermo-optic effects inthe whispering gallery mode (WGM) optical microcavity, without the help ofexternal equipment. Therefore, it has the advantages of small size, lowintegration costs, and self-locking, which shows great potential forapplication. However, the conventional single-channel microcavitythermal-locking method that relies solely on internal thermal balance willinevitably be disturbed by the external environment. This limitation affectsthe locking time and stability. Therefore, in this paper, we propose a newmethod for closed-loop thermal locking of a dual-channel microcavity. Thethermal locking of the signal laser and the thermal regulation of thecontrol laser are carried out respectively by synchronously drawing adual-path tapered fiber. The theoretical model of the thermal dynamics ofthe dual-channel microcavity system is established, and the influence of thecontrol-laser power on the thermal locking of the signal laser is confirmed.The deviation between the locking voltage of the signal laser and the setpoint value is used as a closed-loop feedback parameter to achieve long-termand highly stable mode locking of the signal laser. The results show that inthe 2.63 h thermal-locking test, the locking stability is an order ofmagnitude higher than that of the single tapered fiber. This solutionaddresses the issue of thermal locking being disrupted by the externalenvironment, and offers new possibilities for important applications such asspectroscopy and micro-optical sensor devices.

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 ( 17 )

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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.

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 ( 54 )

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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.

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 ( 12 )

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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.

Tunable artificial plasmonic nanolaser with wide spectrum emission operatingat room temperature

Peng Zhou(周鹏), Jia-Qi Guo(郭佳琦), Kun Liang(梁琨), LeiJin(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 ( 5 )

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With the rapid development of information and communication technology, akey objective in the field of optoelectronic integrated devices is to reducethe nano-laser size and energy consumption. Photonics nanolasers are unableto exceed the diffraction limit and typically exhibit low modulation ratesof several GHz. In contrast, plasmonic nanolaser utilizes highly confinedsurface plasmon polariton (SPP) mode that can exceed diffraction limit andtheir strong Purcell effect can accelerate the modulation rates to severalTHz. Herein, we propose a parametrically tunable artificial plasmonicnanolasers based on metal-insulator-semiconductor-insulator-metal (MISIM) structure, which demonstrates its ability to compress the mode field volumeto $\lambda /14$. As the pump power increases, the proposed artificialplasmonic nanolaser exhibits 20-nm-wide output spectrum. Additionally, weinvestigate the effects of various cavity parameters on the nanolaser'soutput threshold, offering potentials for realizing low-threshold artificialplasmonic nanolasers. Moreover, we observe a blue shift in the centerwavelength 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-basedinterconnects, nano-LEDs, spontaneous emission control, miniaturization ofphoton condensates, eigenmode engineering of plasmonic nanolasers, andoptimal design driven by artificial intelligence (AI).

High-frequency microwave cavity design for high-mass dark matter axion searches

Chi Zhang, Jia Wang, Chunguang Li, Shiguang Chen, Hang Cheng, Liang Sun, and Yun Wu

Chin. Phys. B, 2024, 33 (5): 054211. DOI: 10.1088/1674-1056/ad34ca

Abstract ( 13 )

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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.

Experimental realization of fractal fretwork metasurface for sound anomalous modulation

Jiajie He, Shumeng Yu, Xue Jiang, and Dean Ta

Chin. Phys. B, 2024, 33 (5): 054301. DOI: 10.1088/1674-1056/ad2dcd

Abstract ( 10 )

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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.

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 ( 12 )

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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.

Characteristics of the electromagnetic wavepropagation inmagnetized plasma sheath and practical methodfor 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 ( 4 )

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Magnetic window is considered as an effective method to solve thecommunication blackout issue. COMSOL software package based on the finiteelement method is utilized to simulate the propagation of right-handedcircularly polarized wave in the magnetized plasma sheath. We assume adouble Gaussian model of electron density and an exponential attenuationmodel of magnetic field. The propagation characteristics of right-handedcircularly polarized wave are analyzed by the observation of the reflected,transmitted and loss coefficient. The numerical results show that thepropagation of right-handed circularly polarized wave in the magnetizedplasma sheath varies for different incident angles, collision frequencies,non-uniform magnetic fields and non-uniform plasma densities. We notice thatreducing the wave frequency can meet the propagation conditions of whistlemode in the weak magnetized plasma sheath. And the transmittance of whistlemode is less affected by the variation of the electron density and thecollision frequency. It can be used as a communication window.

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 ( 8 )

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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.

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 ( 5 )

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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.

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, Kai Xie, Yan Liu, Han Xu, Bao Zhang, and De-Yang Tian

Chin. Phys. B, 2024, 33 (5): 055204. DOI: 10.1088/1674-1056/ad2d56

Abstract ( 10 )

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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.

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 ( 10 )

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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.

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 ( 8 )

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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.

High-pressure study on calcium azide (Ca(N$_{\bf 3}$)$_{\bf 2}$): Bending of azide ions stabilizes the structure

Xiaoxin Wu(武晓鑫), Yingjian Wang(王颖健), SiqiLi(李思琪), Juncheng Lv(吕俊呈), JingshuWang(王婧姝), Lihua Yang(杨丽华), Qi Zhang(张旗), Yanqing Liu(刘艳清), Junkai Zhang(张俊凯), and HongshengJia(贾洪声)

Chin. Phys. B, 2024, 33 (5): 056201. DOI: 10.1088/1674-1056/ad2b53

Abstract ( 4 )

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The high-pressure structure and elastic properties of calcium azide(Ca(N$_{3}$)$_{2}$) were investigated using in-situ high-pressure x-ray diffractionand Raman scattering up to 54 GPa and 19 GPa, respectively. Thecompressibility of Ca(N$_{3}$)$_{2}$ changed as the pressure increased, andno phase transition occurred within the pressure from ambient pressure up to 54 GPa. The measured zero-pressure bulk modulus of Ca(N$_{3}$)$_{2 }$ ishigher than that of other alkali metal azides, due to differences in theionic character of their metal-azide bonds. Using CASTEP, all vibrationmodes of Ca(N$_{3}$)$_{2}$ were accurately identified in the vibrationalspectrum at ambient pressure. In the high-pressure vibration study, severalexternal modes (ext.) and internal bending modes ($\nu _2$) of azideanions (N$_{3}^{-}$) softened up to $\sim 7$ GPa and then hardenedbeyond that pressure. This evidence is consistent with the variationobserved in the $F_{\rm E}$-$f_{\rm E}$ data analyzed from the XRD result, where theslope of the curve changes at 7.1 GPa. The main behaviors under pressure arethe alternating compression, rotation, and bending of N$_{3}^{-}$ ions.The bending behavior makes the structure of Ca(N$_{3}$)$_{2}$ more stableunder pressure.

Enhanced superelasticity and reversible elastocaloric effect in nano-grained NiTi alloys with low stress hysteresis

Min Zhou, Wei Wang, Haojian Su, Zhongjun Hu, and Laifeng Li

Chin. Phys. B, 2024, 33 (5): 056501. DOI: 10.1088/1674-1056/ad2a75

Abstract ( 61 )

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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.

Coupling of quasi-localized and phonon modes in glasses at lowfrequency

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 ( 4 )

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Boson peak of glasses, a THz vibrational excess compared to Debyesquared-frequency law, remains mysterious in condensed-matter physics andmaterial science. It appears in many different kinds of glassy matters andis also argued to exist in damped crystals. A consensus is that boson peakoriginates from the coupling of the (quasi)-localized non-phonon modes andthe plane-wave-like phonon modes, but the coupling behavior is still notfully understood. In this paper, by modulating the content of localizedmodes and the frequencies of phonon modes, the coupling is clearly reflectedin the localization and anharmonicity of low-frequency vibrational modes.The coupling enhances with increasing cooling rate and sample size. Forfinite sample size, phonon modes do not fully intrude into the low frequencyto form a dense spectrum and they are not sufficiently coupled tothe localized modes, thus there is no Debye level and boson peak isill-defined. This suggestion remains valid in the presence of thermalmotions induced by temperature, even though the anharmonicity comes intoplay. Our results point to the coupling of quasi-localized and phonon modesand its relation to the boson peak.

Investigation of helicity-dependent photocurrent of surface states in(Bi$_{\bf 0.7}$Sb$_{\bf 0.3}$)$_{\bf 2}$Te$_{\bf 3}$ 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 ( 4 )

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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.

Layered kagome compound Na$_{\bf 2}$Ni$_{\bf 3}$S$_{\bf 4}$ with topological flat band

Junyao Ye, Yihao Lin, Haozhe Wang, Zhida Song, Ji Feng, Weiwei Xie, and Shuang Jia

Chin. Phys. B, 2024, 33 (5): 057103. DOI: 10.1088/1674-1056/ad3431

Abstract ( 10 )

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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.

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 ( 3 )

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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.

Effect of strain on structure and electronic properties of monolayer C$_{\bf 4}$N$_{\bf 4}$

Hao Chen, Ying Xu, Jia-Shi Zhao, and Dan Zhou

Chin. Phys. B, 2024, 33 (5): 057302. DOI: 10.1088/1674-1056/ad260c

Abstract ( 13 )

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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.

Superconductivity in kagome metal ThRu$_{\bf 3}$Si$_{\bf 2}$

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 ( 5 )

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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.

Nonreciprocal transport in the superconducting state of the chiral crystal NbGe$_{\bf 2}$

Yonglai Liu, Xitong Xu, Miao He, Haitian Zhao, Qingqi Zeng, Xingyu Yang, Youming Zou, Haifeng Du, and Zhe Qu

Chin. Phys. B, 2024, 33 (5): 057402. DOI: 10.1088/1674-1056/ad334b

Abstract ( 13 )

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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.

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 ( 16 )

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We report on the magnetization and anomalous Hall effect (AHE) in the high-quality single crystals of the kagome magnet YbMn₆Sn₆, 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 RMn₆Sn₆ compounds. Our band structure calculation reveals a strong hybridization between the 4f electrons of Yb and conduction electrons.

Magnetic and magnetocaloric effect of Er$_{\bf 20}$Ho$_{\bf 20}$Dy$_{\bf 20}$Cu$_{\bf 20}$Ni$_{\bf 20}$ high-entropy metallic glass

Shi-Lin Yu, Lu Tian, Jun-Feng Wang, Xin-Guo Zhao, Da Li, Zhao-Jun Mo, and Bing Li

Chin. Phys. B, 2024, 33 (5): 057502. DOI: 10.1088/1674-1056/ad1a94

Abstract ( 12 )

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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.

Structure, ferroelectric, and enhanced fatigue properties of sol-gel-processed new Bi-based perovskite thin films of Bi(Cu$_{\bf 1/2}$Ti$_{\bf 1/2}$)O$_{\bf 3}$-PbTiO$_{\bf 3}$

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 ( 12 )

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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 30μC/cm$^{2}$ and 16μC/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.

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 ( 4 )

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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.

Atomistic understanding of capacity loss in LiNiO$_{\bf 2}$ 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 ( 15 )

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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.

Accurate estimation of Li/Ni mixing degree of lithium nickel oxidecathode 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 ( 5 )

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Li/Ni mixing negatively influences the discharge capacityof lithium nickel oxide and high-nickel ternary cathode materials. However,accurately measuring the Li/Ni mixing degree is difficult due to thepreferred orientation of lab-based XRD measurements using Bragg--Brentanogeometry. Here, we find that employing spherical harmonics in Rietveldrefinement to eliminate the preferred orientation can significantly decreasethe measurement error of the Li/Ni mixing ratio. The Li/Ni mixing ratioobtained from Rietveld refinement with spherical harmonics shows a strongcorrelation with discharge capacity, which means the electrochemicalcapacity of lithium nickel oxide and high-nickel ternary cathode can beestimated by the Li/Ni mixing degree. Our findings provide a simple andaccurate method to estimate the Li/Ni mixing degree, which is valuable tothe structural analysis and screening of the synthesis conditions of lithiumnickel oxide and high-nickel ternary cathode materials.

A novel order-reduced thermal-coupling electrochemical model for lithium-ion batteries

Yizhan Xie, Shuhui Wang, Zhenpo Wang, and Ximing Cheng

Chin. Phys. B, 2024, 33 (5): 058203. DOI: 10.1088/1674-1056/ad1f52

Abstract ( 9 )

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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.

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 ( 16 )

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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.

A novel complex-high-order graph convolutional network paradigm: ChyGCN

He-Xiang Zheng, Shu-Yu Miao, and Chang-Gui Gu

Chin. Phys. B, 2024, 33 (5): 058401. DOI: 10.1088/1674-1056/ad20db

Abstract ( 9 )

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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.

Tunable superconducting resonators via on-chip control of local magnetic field

Chen-Guang Wang, Wen-Cheng Yue, Xuecou Tu, Tianyuan Chi, Tingting Guo, Yang-Yang Lyu, Sining Dong, Chunhai Cao, Labao Zhang, Xiaoqing Jia, Guozhu Sun, Lin Kang, Jian Chen, Yong-Lei Wang, Huabing Wang, and Peiheng Wu

Chin. Phys. B, 2024, 33 (5): 058402. DOI: 10.1088/1674-1056/ad2f21

Abstract ( 8 )

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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.

Terahertz high-sensitivity SIS mixer based on Nb-AlN-NbN hybrid superconducting tunnel junctions

Bo-Liang Liu(刘博梁), Dong Liu(刘冬), MingYao(姚明), Jun-Da Jin(金骏达), Zheng Wang(王争), JingLi(李婧), Sheng-Cai Shi(史生才), Artem Chekushkin, Michael Fominsky, Lyudmila Filippenko, and ValeryKoshelets

Chin. Phys. B, 2024, 33 (5): 058501. DOI: 10.1088/1674-1056/ad2bf7

Abstract ( 5 )

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The terahertz band, a unique segment of the electromagnetic spectrum, iscrucial for observing the cold, dark universe and plays a pivotal role incutting-edge scientific research, including the study of cosmic environmentsthat support life and imaging black holes. High-sensitivitysuperconductor-insulator-superconductor (SIS) mixers are essential detectorsfor terahertz astronomical telescopes and interferometric arrays. Comparedto the commonly used classical Nb/AlO$_{x}$/Nb superconducting tunneljunction, the Nb/AlN/NbN hybrid superconducting tunnel junction has a higherenergy gap voltage and can achieve a higher critical current density. Thismakes it particularly promising for the development of ultra-wideband,high-sensitivity coherent detectors or mixers in various scientific researchfields. In this paper, we present a superconducting SIS mixer based onNb/AlN/NbN parallel-connected twin junctions (PCTJ), which has a bandwidthextending up to 490 GHz-720 GHz. The best achieved double-sideband (DSB) noisetemperature (sensitivity) is below three times the quantum noise level.

Influence of exchange bias on spin torque ferromagnetic resonancefor 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), GuoqiangYu(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 ( 4 )

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Antiferromagnet (AFM)/ferromagnet (FM) heterostructure is a popular systemfor studying the spin--orbit torque (SOT) of AFMs. However, the interfacialexchange bias field induces that the magnetization in FM layer isnoncollinear to the external magnetic field, namely the magnetic moment drageffect, which further influences the characteristic of SOT efficiency. Inthis work, we study the SOT efficiencies of IrMn/NiFe bilayers with stronginterfacial exchange bias by using spin-torque ferromagnetic resonance(ST-FMR) method. A full analysis on the AFM/FM systems with exchange bias isperformed, and the angular dependence of magnetization on external magneticfield is determined through the minimum rule of free energy. The ST-FMRresults can be well fitted by this model. We obtained the relative accurateSOT efficiency $\xi_{\rm DL} = 0.058$ for the IrMn film. This work providesa useful method to analyze the angular dependence of ST-FMR results andfacilitates the accurate measurement of SOT efficiency for the AFM/FMheterostructures with strong exchange bias.

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 ( 7 )

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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.

In situ luminescence measurements of GaN/Al$_{\bf 2}$O$_{\bf 3}$ film under different energy proton irradiations

Wenli Jiang, Xiao Ouyang, Menglin Qiu, Minju Ying, Lin Chen, Pan Pang, Chunlei Zhang, Yaofeng Zhang, and Bin Liao

Chin. Phys. B, 2024, 33 (5): 058702. DOI: 10.1088/1674-1056/ad1b3f

Abstract ( 9 )

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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.

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 ( 3 )

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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.

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 ( 24 )

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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.

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 ( 4 )

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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.

Estimation of cancer cell migration in biomimetic random/oriented collagen fiber microenvironments

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 ( 8 )

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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.

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 ( 12 )

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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.

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 ( 33 )

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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 to "Absolute partial and total ionization cross sections of carbon monoxide with electron collision from 350 eV to 8000 eV"

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 ( 9 )

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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.

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