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Table of contents

    15 June 2024, Volume 33 Issue 6 Previous issue    Next issue
    TOPICIAL REVIEW—Valleytronics
    Gate-field control of valley polarization in valleytronics
    Ting-Ting Zhang(张婷婷), Yilin Han(韩依琳), Run-Wu Zhang(张闰午), and Zhi-Ming Yu(余智明)
    Chin. Phys. B, 2024, 33 (6):  067303.  DOI: 10.1088/1674-1056/ad401a
    Abstract ( 98 )   HTML ( 0 )   PDF (1595KB) ( 94 )  
    Valleytronics materials are a kind of special semiconductors which can host multiple symmetry-connected and well-separated electron or hole pockets in the Brillouin zone when the system is slightly n or p doped. Since the low-energy particles residing in these pockets generally are not easily scattered to each other by small perturbations, they are endowed with an additional valley degree of freedom. Analogous to spin, the valley freedom can be used to process information, leading to the concept of valleytronics. The prerequisite for valleytronics is the generation of valley polarization. Thus, a focus in this field is achieving the electric generation of valley polarization, especially the static generation by the gate electric field alone. In this work, we briefly review the latest progress in this research direction, focusing on the concepts of the couplings between valley and layer, i.e., the valley-layer coupling which permits the gate-field control of the valley polarization, the couplings between valley, layer, and spin in magnetic systems, the physical properties, the novel designing schemes for electronic devices, and the material realizations of the gate-controlled valleytronics materials.
    TOPICAL REVIEW—States and new effects in nonequilibrium
    K-core attack, equilibrium K-core, and kinetically constrained spin system
    Hai-Jun Zhou(周海军)
    Chin. Phys. B, 2024, 33 (6):  066402.  DOI: 10.1088/1674-1056/ad4329
    Abstract ( 99 )   HTML ( 1 )   PDF (829KB) ( 99 )  
    Kinetically constrained spin systems are toy models of supercooled liquids and amorphous solids. In this perspective, we revisit the prototypical Fredrickson-Andersen (FA) kinetically constrained model from the viewpoint of $K$-core combinatorial optimization. Each kinetic cluster of the FA system, containing all the mutually visitable microscopic occupation configurations, is exactly the solution space of a specific instance of the $K$-core attack problem. The whole set of different jammed occupation patterns of the FA system is the configuration space of an equilibrium $K$-core problem. Based on recent theoretical results achieved on the $K$-core attack and equilibrium $K$-core problems, we discuss the thermodynamic spin glass phase transitions and the maximum occupation density of the fully unfrozen FA kinetic cluster, and the minimum occupation density and extreme vulnerability of the partially frozen (jammed) kinetic clusters. The equivalence between $K$-core attack and the fully unfrozen FA kinetic cluster also implies a new way of sampling $K$-core attack solutions.
    SPECIAL TOPIC—Heat conduction and its related interdisciplinary areas
    Theoretical study on the effective thermal conductivity of silica aerogels based on a cross-aligned and cubic pore model
    Kuncan Zheng(郑坤灿), Zhendong Li(李震东), Yutong Cao(曹豫通), Ben Liu(刘犇)), and Junlei Hu(胡君磊)
    Chin. Phys. B, 2024, 33 (6):  064401.  DOI: 10.1088/1674-1056/ad47ac
    Abstract ( 93 )   HTML ( 1 )   PDF (1786KB) ( 67 )  
    Aerogel nanoporous materials possess high porosity, high specific surface area, and extremely low density due to their unique nanoscale network structure. Moreover, their effective thermal conductivity is very low, making them a new type of lightweight and highly efficient nanoscale super-insulating material. However, prediction of their effective thermal conductivity is challenging due to their uneven pore size distribution. To investigate the internal heat transfer mechanism of aerogel nanoporous materials, this study constructed a cross-aligned and cubic pore model (CACPM) based on the actual pore arrangement of SiO$_{2}$ aerogel. Based on the established CACPM, the effective thermal conductivity expression for the aerogel was derived by simultaneously considering gas-phase heat conduction, solid-phase heat conduction, and radiative heat transfer. The derived expression was then compared with available experimental data and the Wei structure model. The results indicate that, according to the model established in this study for the derived thermal conductivity formula of silica aerogel, for powdery silica aerogel under the conditions of $T=298$K, $a_{2} =0.85$, $D_{1} =90μ $m, $\rho =128{\rm kg/m}^{3}$, within the pressure range of 0-10$^{5}$Pa, the average deviation between the calculated values and experimental values is 10.51%. In the pressure range of 10$^{3}$-10$^{4}$Pa, the deviation between calculated values and experimental values is within 4%. Under these conditions, the model has certain reference value in engineering verification. This study also makes a certain contribution to the research of aerogel thermal conductivity heat transfer models and calculation formulae.
    INSTRUMENTATION AND MEASUREMENT
    Imaging plate scanners calibration and the attenuation behavior of imaging plate signals
    Nan Bo(薄楠) and Nai-Yan Wang(王乃彦)
    Chin. Phys. B, 2024, 33 (6):  060701.  DOI: 10.1088/1674-1056/ad43d4
    Abstract ( 51 )   HTML ( 1 )   PDF (907KB) ( 55 )  
    Based on previously reported work, we propose a new method for calibrating image plate (IP) scanners, offering greater flexibility and convenience, which can be extended to the calibration tasks of various scanner models. This method was applied to calibrate the sensitivity of a GE Typhoon FLA 7000 scanner. Additionally, we performed a calibration of the spontaneous signal attenuation behavior for BAS-MS, BAS-SR, and BAS-TR type IPs under the 20$\pm$1$^\circ$C environmental conditions, and observed significant signal carrier diffusion behavior in BAS-MS IP. The calibration results lay a foundation for further research on the interaction between ultra-short, ultra-intense lasers and matter.
    RAPID COMMUNICATION
    Controlling the dynamic behavior of decentralized cluster through centralized approaches Hot!
    Daming Yuan(袁大明), Peilong Wang(王培龙), Peng Wang(王鹏), Xingyu Ma(马星宇), Chuyun Wang(汪楚云), Jing Wang(王璟), Huaicheng Chen(陈怀城), Gao Wang(王高), and Fangfu Ye(叶方富)
    Chin. Phys. B, 2024, 33 (6):  060702.  DOI: 10.1088/1674-1056/ad3dd0
    Abstract ( 326 )   HTML ( 2 )   PDF (3679KB) ( 332 )  
    How to control the dynamic behavior of large-scale artificial active matter is a critical concern in experimental research on soft matter, particularly regarding the emergence of collective behaviors and the formation of group patterns. Centralized systems excel in precise control over individual behavior within a group, ensuring high accuracy and controllability in task execution. Nevertheless, their sensitivity to group size may limit their adaptability to diverse tasks. In contrast, decentralized systems empower individuals with autonomous decision-making, enhancing adaptability and system robustness. Yet, this flexibility comes at the cost of reduced accuracy and efficiency in task execution. In this work, we present a unique method for regulating the centralized dynamic behavior of self-organizing clusters based on environmental interactions. Within this environment-coupled robot system, each robot possesses similar dynamic characteristics, and their internal programs are entirely identical. However, their behaviors can be guided by the centralized control of the environment, facilitating the accomplishment of diverse cluster tasks. This approach aims to balance the accuracy and flexibility of centralized control with the robustness and task adaptability of decentralized control. The proactive regulation of dynamic behavioral characteristics in active matter groups, demonstrated in this work through environmental interactions, holds the potential to introduce a novel technological approach and provide experimental references for studying the dynamic behavior control of large-scale artificial active matter systems.
    Anisotropic metal-insulator transition in strained VO2(B) single crystal
    Zecheng Ma(马泽成), Shengnan Yan(闫胜楠), Zenglin Liu(刘增霖), Tao Xu(徐涛), Fanqiang Chen(陈繁强), Sicheng Chen(陈思成), Tianjun Cao(曹天俊), Litao Sun(孙立涛), Bin Cheng(程斌), Shi-Jun Liang(梁世军), and Feng Miao(缪峰)
    Chin. Phys. B, 2024, 33 (6):  067103.  DOI: 10.1088/1674-1056/ad39d4
    Abstract ( 79 )   HTML ( 1 )   PDF (4582KB) ( 43 )  
    Mechanical strain can induce noteworthy structural and electronic changes in vanadium dioxide, imparting substantial scientific importance to both the exploration of phase transitions and the development of potential technological applications. Unlike the traditional rutile (R) phase, bronze-phase vanadium dioxide [VO$_{2}$(B)] exhibits an in-plane anisotropic structure. When subjected to stretching along distinct crystallographic axes, VO$_{2}$(B) may further manifest the axial dependence in lattice-electron interactions, which is beneficial for gaining insights into the anisotropy of electronic transport. Here, we report an anisotropic room-temperature metal-insulator transition in single-crystal VO$_{2}$(B) by applying in-situ uniaxial tensile strain. This material exhibits significantly different electromechanical responses along two anisotropic axes. We reveal that such an anisotropic electromechanical response mainly arises from the preferential arrangement of a strain-induced unidirectional stripe state in the conductive channel. This insulating stripe state could be attributed to the in-plane dimerization within the distorted zigzag chains of vanadium atoms, evidenced by strain-modulated Raman spectra. Our work may open up a promising avenue for exploiting the anisotropy of metal-insulator transition in vanadium dioxide for potential technological applications.
    Unveiling the pressure-driven metal-semiconductor-metal transition in the doped TiS2 Hot!
    Jiajun Chen(陈佳骏), Xindeng Lv(吕心邓), Simin Li(李思敏), Yaqian Dan(但雅倩), Yanping Huang(黄艳萍), and Tian Cui(崔田)
    Chin. Phys. B, 2024, 33 (6):  067104.  DOI: 10.1088/1674-1056/ad4325
    Abstract ( 152 )   HTML ( 0 )   PDF (1175KB) ( 241 )  
    Conventional theories expect that materials under pressure exhibit expanded valence and conduction bands, leading to increased electrical conductivity. Here, we report the electrical properties of the doped 1$T$-TiS$_{2}$ under high pressure by electrical resistance investigations, synchrotron x-ray diffraction, Raman scattering and theoretical calculations. Up to 70GPa, an unusual metal-semiconductor-metal transition occurs. Our first-principles calculations suggest that the observed anti-Wilson transition from metal to semiconductor at 17GPa is due to the electron localization induced by the intercalated Ti atoms. This electron localization is attributed to the strengthened coupling between the doped Ti atoms and S atoms, and the Anderson localization arising from the disordered intercalation. At pressures exceeding 30.5GPa, the doped TiS$_{2}$ undergoes a re-metallization transition initiated by a crystal structure phase transition. We assign the most probable space group as $P$2$_{1}$2$_{1}$2$_{1}$. Our findings suggest that materials probably will eventually undergo the Wilson transition when subjected to sufficient pressure.
    Field induced Chern insulating states in twisted monolayer-bilayer graphene Hot!
    Zhengwen Wang(王政文), Yingzhuo Han(韩英卓), Kenji Watanabe, Takashi Taniguchi, Yuhang Jiang(姜宇航), and Jinhai Mao(毛金海)
    Chin. Phys. B, 2024, 33 (6):  067301.  DOI: 10.1088/1674-1056/ad3b8a
    Abstract ( 225 )   HTML ( 1 )   PDF (1262KB) ( 309 )  
    Unraveling the mechanism underlying topological phases, notably the Chern insulators (ChIs) in strong correlated systems at the microscopy scale, has captivated significant research interest. Nonetheless, ChIs harboring topological information have not always manifested themselves, owing to the constraints imposed by displacement fields in certain experimental configurations. In this study, we employ density-tuned scanning tunneling microscopy (DT-STM) to investigate the ChIs in twisted monolayer-bilayer graphene (tMBG). At zero magnetic field, we observe correlated metallic states. While under a magnetic field, a metal-insulator transition happens and an integer ChI is formed emanating from the filling index $ s = 3$ with a Chern number $C = 1$. Our results underscore the pivotal role of magnetic fields as a powerful probe for elucidating topological phases in twisted Van der Waals heterostructures.
    Reanalysis of energy band structure in the type-II quantum wells
    Xinxin Li(李欣欣), Zhen Deng(邓震), Yang Jiang(江洋), Chunhua Du(杜春花), Haiqiang Jia(贾海强), Wenxin Wang(王文新), and Hong Chen(陈弘)
    Chin. Phys. B, 2024, 33 (6):  067302.  DOI: 10.1088/1674-1056/ad36bc
    Abstract ( 89 )   HTML ( 0 )   PDF (670KB) ( 78 )  
    Band structure analysis holds significant importance for understanding the optoelectronic characteristics of semiconductor structures and exploring their potential applications in practice. For quantum well structures, the energy of carriers in the well splits into discrete energy levels due to the confinement of barriers in the growth direction. However, the discrete energy levels obtained at a fixed wave vector cannot accurately reflect the actual energy band structure. In this work, the band structure of the type-II quantum wells is reanalyzed. When the wave vectors of the entire Brillouin region (corresponding to the growth direction) are taken into account, the quantized energy levels of the carriers in the well are replaced by subbands with certain energy distributions. This new understanding of the energy bands of low-dimensional structures not only helps us to have a deeper cognition of the structure, but also may overturn many viewpoints in traditional band theories and serve as supplementary to the band theory of low-dimensional systems.
    Revisit of the anisotropic vortex states of 2H-NbSe2 towards the zero-field limit
    Fan Zhang(张凡), Xingyuan Hou(侯兴元), Yuxuan Jiang(姜宇轩), Zongyuan Zhang(张宗源), Yubing Tu(涂玉兵), Xiangde Zhu(朱相德), Genfu Chen(陈根富), and Lei Shan(单磊)
    Chin. Phys. B, 2024, 33 (6):  067401.  DOI: 10.1088/1674-1056/ad362d
    Abstract ( 88 )   HTML ( 1 )   PDF (8013KB) ( 101 )  
    We revisited the vortex states of 2H-NbSe$_{2}$ towards zero fields by a low-temperature scanning tunneling microscope. Fine structures of the anisotropic vortex states were distinguished, one is a spatially non-splitting zero bias peak, and the other is an in-gap conductance anomaly resembling evolved crossing features around the center of the three nearest vortices. Both of them distribute solely along the next nearest neighboring direction of the vortex lattice and become unresolved in much higher magnetic fields, implying an important role played by the vortex-vortex interactions. To clarify these issues, we have studied the intrinsic vortex states of the isolated trapped vortex in zero fields at 0.45K. It is concluded that the anisotropic zero bias peak is attributed to the superconducting gap anisotropy, and the spatially evolved crossing features are related to the vortex-vortex interaction. The vortex core size under the zero-field limit is determined. These results provide a paradigm for studying the inherent vortex states of type-I\!I superconductors especially based on an isolated vortex.
    Surface doping manipulation of the insulating ground states in Ta2Pd3Te5 and Ta2Ni3Te5
    Bei Jiang(江北), Jingyu Yao(姚静宇), Dayu Yan(闫大禹), Zhaopeng Guo(郭照芃), Gexing Qu(屈歌星), Xiutong Deng(邓修同), Yaobo Huang(黄耀波), Hong Ding(丁洪), Youguo Shi(石友国), Zhijun Wang(王志俊), and Tian Qian(钱天)
    Chin. Phys. B, 2024, 33 (6):  067402.  DOI: 10.1088/1674-1056/ad362e
    Abstract ( 89 )   HTML ( 1 )   PDF (1656KB) ( 78 )  
    Manipulating emergent quantum phenomena is a key issue for understanding the underlying physics and contributing to possible applications. Here we study the evolution of insulating ground states of Ta$_{2}$Pd$_{3}$Te$_{5}$ and Ta$_{2}$Ni$_{3}$Te$_{5}$ under in-situ surface potassium deposition via angle-resolved photoemission spectroscopy. Our results confirm the excitonic insulator character of Ta$_{2}$Pd$_{3}$Te$_{5}$. Upon surface doping, the size of its global gap decreases obviously. After a deposition time of more than 7 min, the potassium atoms induce a metal-insulator phase transition and make the system recover to a normal state. In contrast, our results show that the isostructural compound Ta$_{2}$Ni$_{3}$Te$_{5}$ is a conventional insulator. The size of its global gap decreases upon surface doping, but persists positive throughout the doping process. Our results not only confirm the excitonic origin of the band gap in Ta$_{2}$Pd$_{3}$Te$_{5}$, but also offer an effective method for designing functional quantum devices in the future.
    Semiclassical approach to spin dynamics of a ferromagnetic S=1 chain Hot!
    Chengchen Li(李承晨), Yi Cui(崔祎), Weiqiang Yu(于伟强), and Rong Yu(俞榕)
    Chin. Phys. B, 2024, 33 (6):  067501.  DOI: 10.1088/1674-1056/ad3c32
    Abstract ( 107 )   HTML ( 0 )   PDF (1107KB) ( 153 )  
    Motivated by recent experimental progress on the quasi-one-dimensional quantum magnet NiNb$_2$O$_6$, we study the spin dynamics of an $S=1$ ferromagnetic Heisenberg chain with single-ion anisotropy by using a semiclassical molecular dynamics approach. This system undergoes a quantum phase transition from a ferromagnetic to a paramagnetic state under a transverse magnetic field, and the magnetic response reflecting this transition is well described by our semiclassical method. We show that at low temperature the transverse component of the dynamical structure factor depicts clearly the magnon dispersion, and the longitudinal component exhibits two continua associated with single- and two-magnon excitations, respectively. These spin excitation spectra show interesting temperature dependence as effects of magnon interactions. Our findings shed light on the experimental detection of spin excitations in a large class of quasi-one-dimensional magnets.
    Relationship between disorder, magnetism and band topology in Mn(Sb1-xBix)2Te4 single crystals Hot!
    Ming Xi(席明) and Hechang Lei(雷和畅)
    Chin. Phys. B, 2024, 33 (6):  067503.  DOI: 10.1088/1674-1056/ad3dd8
    Abstract ( 164 )   HTML ( 0 )   PDF (919KB) ( 251 )  
    We investigate the evolution of magnetic properties as well as the content and distribution of Mn for Mn(Sb$_{1-x}$Bi$_{x}$)$_{2}$Te$_{4}$ single crystals grown by large-temperature-gradient chemical vapor transport method. It is found that the ferromagnetic MnSb$_{2}$Te$_{4}$ changes to antiferromagnetism with Bi doping when $x \ge 0.25$. Further analysis implies that the occupations of Mn ions at Sb/Bi site Mn$_{\rm Sb/Bi}$ and Mn site Mn$_{\rm Mn}$ have a strong influence on the magnetic ground states of these systems. With the decrease of Mn$_{\rm Mn}$ and increase of Mn$_{\rm Sb/Bi}$, the system will favor the ferromagnetic ground state. In addition, the rapid decrease of $T_{\rm C/N}$ with increasing Bi content when $x \le 0.25$ and the insensitivity of $T_{\rm N}$ to $x$ when $x > 0.25$ suggest that the main magnetic interaction may change from the Ruderman-Kittel-Kasuya-Yosida type at low Bi doping region to the van-Vleck type in high Bi doped samples.
    Photoinduced Floquet higher-order Weyl semimetal in C6 symmetric Dirac semimetals
    Xin-Xin Xu(许欣欣), Zi-Ming Wang(王梓名), Dong-Hui Xu(许东辉), and Chui-Zhen Chen(陈垂针)
    Chin. Phys. B, 2024, 33 (6):  067801.  DOI: 10.1088/1674-1056/ad4634
    Abstract ( 90 )   HTML ( 0 )   PDF (1930KB) ( 43 )  
    Topological Dirac semimetals are a parent state from which other exotic topological phases of matter, such as Weyl semimetals and topological insulators, can emerge. In this study, we investigate a Dirac semimetal possessing sixfold rotational symmetry and hosting higher-order topological hinge Fermi arc states, which is irradiated by circularly polarized light. Our findings reveal that circularly polarized light splits each Dirac node into a pair of Weyl nodes due to the breaking of time-reversal symmetry, resulting in the realization of the Weyl semimetal phase. This Weyl semimetal phase exhibits rich boundary states, including two-dimensional surface Fermi arc states and hinge Fermi arc states confined to six hinges. Furthermore, by adjusting the incident direction of the circularly polarized light, we can control the degree of tilt of the resulting Weyl cones, enabling the realization of different types of Weyl semimetals.
    GENERAL
    Multi-soliton solutions, breather-like and bound-state solitons for complex modified Korteweg-de Vries equation in optical fibers
    Zhong-Zhou Lan(兰中周)
    Chin. Phys. B, 2024, 33 (6):  060201.  DOI: 10.1088/1674-1056/ad39d7
    Abstract ( 114 )   HTML ( 0 )   PDF (984KB) ( 131 )  
    Under investigation in this paper is a complex modified Korteweg-de Vries (KdV) equation, which describes the propagation of short pulses in optical fibers. Bilinear forms and multi-soliton solutions are obtained through the Hirota method and symbolic computation. Breather-like and bound-state solitons are constructed in which the signs of the imaginary parts of the complex wave numbers and the initial separations of the two parallel solitons are important factors for the interaction patterns. The periodic structures and position-induced phase shift of some solutions are introduced.
    Mechanism analysis of regulating Turing instability and Hopf bifurcation of malware propagation in mobile wireless sensor networks
    Xi-Xi Huang(黄习习), Min Xiao(肖敏), Leszek Rutkowski, Hai-Bo Bao(包海波), Xia Huang(黄霞), and Jin-De Cao(曹进德)
    Chin. Phys. B, 2024, 33 (6):  060202.  DOI: 10.1088/1674-1056/ad24d5
    Abstract ( 91 )   HTML ( 0 )   PDF (4371KB) ( 100 )  
    A dynamical model is constructed to depict the spatial-temporal evolution of malware in mobile wireless sensor networks (MWSNs). Based on such a model, we design a hybrid control scheme combining parameter perturbation and state feedback to effectively manipulate the spatiotemporal dynamics of malware propagation. The hybrid control can not only suppress the Turing instability caused by diffusion factor but can also adjust the occurrence of Hopf bifurcation induced by time delay. Numerical simulation results show that the hybrid control strategy can efficiently manipulate the transmission dynamics to achieve our expected desired properties, thus reducing the harm of malware propagation to MWSNs.
    Performance enhancement of a viscoelastic bistable energy harvester using time-delayed feedback control
    Mei-Ling Huang(黄美玲), Yong-Ge Yang(杨勇歌), and Yang Liu(刘洋)
    Chin. Phys. B, 2024, 33 (6):  060203.  DOI: 10.1088/1674-1056/ad3b89
    Abstract ( 66 )   HTML ( 0 )   PDF (2804KB) ( 40 )  
    This paper focuses on the stochastic analysis of a viscoelastic bistable energy harvesting system under colored noise and harmonic excitation, and adopts the time-delayed feedback control to improve its harvesting efficiency. Firstly, to obtain the dimensionless governing equation of the system, the original bistable system is approximated as a system without viscoelastic term by using the stochastic averaging method of energy envelope, and then is further decoupled to derive an equivalent system. The credibility of the proposed method is validated by contrasting the consistency between the numerical and the analytical results of the equivalent system under different noise conditions. The influence of system parameters on average output power is analyzed, and the control effect of the time-delayed feedback control on system performance is compared. The output performance of the system is improved with the occurrence of stochastic resonance (SR). Therefore, the signal-to-noise ratio expression for measuring SR is derived, and the dependence of its SR behavior on different parameters is explored.
    Mobility edges and localization characteristics in one-dimensional quasiperiodic quantum walk
    Xin-Hui Cui(崔鑫辉), Hui-Min Wang(王慧敏), and Zhi-Jian Li(李志坚)
    Chin. Phys. B, 2024, 33 (6):  060301.  DOI: 10.1088/1674-1056/ad342d
    Abstract ( 75 )   HTML ( 0 )   PDF (3217KB) ( 62 )  
    We construct a one-dimensional quasiperiodic quantum walk to investigate the localization-delocalization transition. The inverse participation ratio and Lyapunov exponent are employed as two indexes to determine the mobility edge, a critical energy to distinguish the energy regions of extended and localized states. The analytical solution of mobility edge is obtained by the Lyapunov exponents in global theory, and the consistency of the two indexes is confirmed. We further study the dynamic characteristics of the quantum walk and show that the probabilities are localized to some specific lattice sites with time evolution. This phenomenon is explained by the effective potential of the Hamiltonian which corresponds to the phase in the coin operator of the quantum walk.
    Anomalous time-reversal symmetric non-Hermitian systems
    Yifei Yi(易益妃)
    Chin. Phys. B, 2024, 33 (6):  060302.  DOI: 10.1088/1674-1056/ad2502
    Abstract ( 87 )   HTML ( 0 )   PDF (1302KB) ( 114 )  
    The conditions for the emergence of the non-Hermitian skin effect, as a unique physical response of non-Hermitian systems, have now become one of the hot research topics. In this paper, we study the novel physical responses of non-Hermitian systems with anomalous time-reversal symmetry, in both one dimension and two dimensions. Specifically, we focus on whether the systems will exhibit a non-Hermitian skin effect. We employ the theory of generalized Brillouin zone and also numerical methods to show that the anomalous time-reversal symmetry can prevent the skin effect in one-dimensional non-Hermitian systems, but is unable to exert the same effectiveness in two-dimensional cases.
    Quantum discord and its dynamics for multipartite systems
    Jiaxin Luo(罗嘉欣) and Qiong Guo(郭琼)
    Chin. Phys. B, 2024, 33 (6):  060303.  DOI: 10.1088/1674-1056/ad3810
    Abstract ( 85 )   HTML ( 0 )   PDF (1144KB) ( 52 )  
    Quantum discord, one of the famous quantum correlations, has been recently generalized to multipartite systems by Radhakrishnan et al. Here we give analytical solutions of the quantum discord for a family of $N$-qubit quantum states. For the bipartite system, we derive a zero quantum discord which will remain unchanged under the phase damping channel. For multiparitite systems, it is found that the quantum discord can be classified into three categories and the quantum discord for odd-partite systems can exhibit freezing under the phase damping channel, while the freezing does not exist in the even-partite systems.
    Enhancing quantum metrology for multiple frequencies of oscillating magnetic fields by quantum control
    Xin Lei(雷昕), Jingyi Fan(范静怡), and Shengshi Pang(庞盛世)
    Chin. Phys. B, 2024, 33 (6):  060304.  DOI: 10.1088/1674-1056/ad3430
    Abstract ( 73 )   HTML ( 0 )   PDF (840KB) ( 87 )  
    Quantum multi-parameter estimation has recently attracted increased attention due to its wide applications, with a primary goal of designing high-precision measurement schemes for unknown parameters. While existing research has predominantly concentrated on time-independent Hamiltonians, little has been known about quantum multi-parameter estimation for time-dependent Hamiltonians due to the complexity of quantum dynamics. This work bridges the gap by investigating the precision limit of multi-parameter quantum estimation for a qubit in an oscillating magnetic field model with multiple unknown frequencies. As the well-known quantum Cramér-Rao bound is generally unattainable due to the potential incompatibility between the optimal measurements for different parameters, we use the most informative bound instead which is always attainable and equivalent to the Holevo bound in the asymptotic limit. Moreover, we apply additional Hamiltonian to the system to engineer the dynamics of the qubit. By utilizing the quasi-Newton method, we explore the optimal schemes to attain the highest precision for the unknown frequencies of the magnetic field, including the simultaneous optimization of initial state preparation, the control Hamiltonian and the final measurement. The results indicate that the optimization can yield much higher precisions for the field frequencies than those without the optimizations. Finally, we study the robustness of the optimal control scheme with respect to the fluctuation of the interested frequencies, and the optimized scheme exhibits superior robustness to the scenario without any optimization.
    Topological laser on square lattice with gain-loss-induced higher-order corner modes
    Ming-Jie Liao(廖明杰), Mei-Song Wei(韦梅松), Shuailing Wang(王帅领), Jingping Xu(许静平), and Yaping Yang(羊亚平)
    Chin. Phys. B, 2024, 33 (6):  060305.  DOI: 10.1088/1674-1056/ad322a
    Abstract ( 75 )   HTML ( 0 )   PDF (1148KB) ( 77 )  
    We investigate the higher-order topological laser in the two-dimensional (2D) coupled-cavity array. By adding staggered on-site gain and loss to the 2D Hermitian array with a trivial phase, the system will emerge degenerate topological corner modes, which are protected by bulk band gap. For such a non-Hermitian model, by adjusting the parameters of the system and introducing the pumping into the cavity at the corner, a single-mode lasing with topological protection emerges. Furthermore, single-mode lasing exists over a wide range of pumping strengths. No matter where the cavity is initially stimulated, after enough time evolution, all the cavities belonging to the topological corner mode can emit a stable laser.
    Robust optical mode converter based on topological waveguide arrays
    Yu-Xiang Xu(徐宇翔), Wen-Jian Tang(唐文剑), Li-Wei Jiang(姜力炜), De-Xing Wu(吴德兴), Heng Wang(王恒), Bing-Cong Xu(许冰聪), and Lin Chen(陈林)
    Chin. Phys. B, 2024, 33 (6):  060306.  DOI: 10.1088/1674-1056/ad3811
    Abstract ( 99 )   HTML ( 0 )   PDF (1444KB) ( 90 )  
    Optical mode converters are essential for enhancing the capacity of optical communication systems. However, fabrication errors restrict the further improvement of conventional mode converters. To address this challenge, we have designed an on-chip TE$_{0}$-TE$_{1}$ mode converter based on topologically protected waveguide arrays. The simulation results demonstrate that the converter exhibits a mode coupling efficiency of 93.5% near 1550nm and can tolerate a relative fabrication error of 30%. Our design approach can be extended to enhance the robustness for other integrated photonic devices, beneficial for future development of optical network systems.
    Wigner function of optical cumulant operator and its dissipation in thermo-entangled state representation
    Ke Zhang(张科), Lan-Lan Li(李兰兰), and Hong-Yi Fan(范洪义)
    Chin. Phys. B, 2024, 33 (6):  060307.  DOI: 10.1088/1674-1056/ad2f20
    Abstract ( 85 )   HTML ( 0 )   PDF (453KB) ( 80 )  
    To conveniently calculate the Wigner function of the optical cumulant operator and its dissipation evolution in a thermal environment, in this paper, the thermo-entangled state representation is introduced to derive the general evolution formula of the Wigner function, and its relation to Weyl correspondence is also discussed. The method of integration within the ordered product of operators is essential to our discussion.
    Exceptional points and quantum dynamics in a non-Hermitian two-qubit system
    Yi-Xi Zhang(张益玺), Zhen-Tao Zhang(张振涛), Zhen-Shan Yang(杨震山), Xiao-Zhi Wei(魏晓志), and Bao-Long Liang(梁宝龙)
    Chin. Phys. B, 2024, 33 (6):  060308.  DOI: 10.1088/1674-1056/ad2a70
    Abstract ( 77 )   HTML ( 0 )   PDF (2186KB) ( 129 )  
    We study the exceptional-point (EP) structure and the associated quantum dynamics in a system consisting of a non-Hermitian qubit and a Hermitian qubit. We find that the system possesses two sets of EPs, which divide the system-parameter space into $\mathcal{PT}$-symmetry unbroken, partially broken and fully broken regimes, each with distinct quantum-dynamics characteristics. Particularly, in the partially broken regime, while the $\mathcal{PT}$-symmetry is generally broken in the whole four-dimensional Hilbert space, it is preserved in a two-dimensional subspace such that the quantum dynamics in the subspace are similar to those in the $\mathcal{PT}$-symmetry unbroken regime. In addition, we reveal that the competition between the inter-qubit coupling and the intra-qubit driving gives rise to a complex pattern in the EP variation with system parameters.
    A quantum blind signature scheme based on dense coding for non-entangled states
    Ke Xing(邢柯), Ai-Han Yin(殷爱菡), and Yong-Qi Xue(薛勇奇)
    Chin. Phys. B, 2024, 33 (6):  060309.  DOI: 10.1088/1674-1056/ad2bed
    Abstract ( 72 )   HTML ( 0 )   PDF (497KB) ( 72 )  
    In some schemes, quantum blind signatures require the use of difficult-to-prepare multiparticle entangled states. By considering the communication overhead, quantum operation complexity, verification efficiency and other relevant factors in practical situations, this article proposes a non-entangled quantum blind signature scheme based on dense encoding. The information owner utilizes dense encoding and hash functions to blind the information while reducing the use of quantum resources. After receiving particles, the signer encrypts the message using a one-way function and performs a Hadamard gate operation on the selected single photon to generate the signature. Then the verifier performs a Hadamard gate inverse operation on the signature and combines it with the encoding rules to restore the message and complete the verification. Compared with some typical quantum blind signature protocols, this protocol has strong blindness in privacy protection, and higher flexibility in scalability and application. The signer can adjust the signature operation according to the actual situation, which greatly simplifies the complexity of the signature. By simultaneously utilizing the secondary distribution and rearrangement of non-entangled quantum states, a non-entangled quantum state representation of three bits of classical information is achieved, reducing the use of a large amount of quantum resources and lowering implementation costs. This improves both signature verification efficiency and communication efficiency while, at the same time, this scheme meets the requirements of unforgeability, non-repudiation, and prevention of information leakage.
    Design of a novel hybrid quantum deep neural network in INEQR images classification
    Shuang Wang(王爽), Ke-Han Wang(王柯涵), Tao Cheng(程涛), Run-Sheng Zhao(赵润盛), Hong-Yang Ma(马鸿洋), and Shuai Guo(郭帅)
    Chin. Phys. B, 2024, 33 (6):  060310.  DOI: 10.1088/1674-1056/ad342e
    Abstract ( 97 )   HTML ( 0 )   PDF (1583KB) ( 88 )  
    We redesign the parameterized quantum circuit in the quantum deep neural network, construct a three-layer structure as the hidden layer, and then use classical optimization algorithms to train the parameterized quantum circuit, thereby propose a novel hybrid quantum deep neural network (HQDNN) used for image classification. After bilinear interpolation reduces the original image to a suitable size, an improved novel enhanced quantum representation (INEQR) is used to encode it into quantum states as the input of the HQDNN. Multi-layer parameterized quantum circuits are used as the main structure to implement feature extraction and classification. The output results of parameterized quantum circuits are converted into classical data through quantum measurements and then optimized on a classical computer. To verify the performance of the HQDNN, we conduct binary classification and three classification experiments on the MNIST (Modified National Institute of Standards and Technology) data set. In the first binary classification, the accuracy of 0 and 4 exceeds $98%$. Then we compare the performance of three classification with other algorithms, the results on two datasets show that the classification accuracy is higher than that of quantum deep neural network and general quantum convolutional neural network.
    Interplay between topology and localization on superconducting circuits
    Xin Guan(关欣), Bingyan Huo(霍炳燕), and Gang Chen(陈刚)
    Chin. Phys. B, 2024, 33 (6):  060311.  DOI: 10.1088/1674-1056/ad342c
    Abstract ( 74 )   HTML ( 0 )   PDF (1256KB) ( 36 )  
    Topological insulators occupy a prominent position in the realm of condensed matter physics. Nevertheless, the presence of strong disorder has the potential to disrupt the integrity of topological states, leading to the localization of all states. This study delves into the intricate interplay between topology and localization within the one-dimensional Su-Schrieffer-Heeger (SSH) model, which incorporates controllable off-diagonal quasi-periodic modulations on superconducting circuits. Through the application of external alternating current (ac) magnetic fluxes, each transmon undergoes controlled driving, enabling independent tuning of all coupling strengths. Within a framework of this model, we construct comprehensive phase diagrams delineating regions characterized by extended topologically nontrivial states, critical localization, and co-existing topological and critical localization phases. The paper also addresses the dynamics of qubit excitations, elucidating distinct quantum state transfers resulting from the intricate interplay between topology and localization. Additionally, we propose a method for detecting diverse quantum phases utilizing existing experimental setups.
    Electric field dependence of spin qubit in a Si-MOS quantum dot
    Rong-Long Ma(马荣龙), Ming Ni(倪铭), Yu-Chen Zhou(周雨晨), Zhen-Zhen Kong(孔真真), Gui-Lei Wang(王桂磊), Di Liu(刘頔), Gang Luo(罗刚), Gang Cao(曹刚), Hai-Ou Li(李海欧), and Guo-Ping Guo(郭国平)
    Chin. Phys. B, 2024, 33 (6):  060312.  DOI: 10.1088/1674-1056/ad3812
    Abstract ( 77 )   HTML ( 0 )   PDF (730KB) ( 85 )  
    Valley, the intrinsic feature of silicon, is an inescapable subject in silicon-based quantum computing. At the spin-valley hotspot, both Rabi frequency and state relaxation rate are significantly enhanced. With protection against charge noise, the valley degree of freedom is also conceived to encode a qubit to realize noise-resistant quantum computing. Here, based on the spin qubit composed of one or three electrons, we characterize the intrinsic properties of valley in an isotopically enriched silicon quantum dot (QD) device. For one-electron qubit, we measure two electric-dipole spin resonance (EDSR) signals which are attributed to partial occupation of two valley states. The resonance frequencies of two EDSR signals have opposite electric field dependences. Moreover, we characterize the electric field dependence of the upper valley state based on three-electron qubit experiments. The difference of electric field dependences of the two valleys is 52.02MHz/V, which is beneficial for tuning qubit frequency to meet different experimental requirements. As an extension of electrical control spin qubits, the opposite electric field dependence is crucial for qubit addressability, individual single-qubit control and two-qubit gate approaches in scalable quantum computing.
    Nonlinearly induced entanglement in dissipatively coupled optomechanical system
    Wen-Quan Yang(杨文全), Xuan Leng(冷轩), Jiong Cheng(程泂), and Wen-Zhao Zhang(张闻钊)
    Chin. Phys. B, 2024, 33 (6):  060313.  DOI: 10.1088/1674-1056/ad3dd6
    Abstract ( 93 )   HTML ( 0 )   PDF (747KB) ( 49 )  
    Nonlinearly induced steady-state photon-phonon entanglement of a dissipative coupled system is studied in the bistable regime. Quantum dynamical characteristics are analysed by solving the mean-field and fluctuation equations of the system. It is shown that dissipative coupling can induce bistable behaviour for the effective dissipation of the system. Under suitable parameters, one of the steady states significantly reduces the dissipative effect of the system. Consequently, a larger steady-state entanglement can be achieved compared to linear dynamics. Furthermore, the experimental feasibility of the parameters is analysed. Our results provide a new perspective for the implementation of steady-state optomechanical entanglement.
    Decoding topological XYZ2 codes with reinforcement learning based on attention mechanisms
    Qing-Hui Chen(陈庆辉), Yu-Xin Ji(姬宇欣), Ke-Han Wang(王柯涵), Hong-Yang Ma(马鸿洋), and Nai-Hua Ji(纪乃华)
    Chin. Phys. B, 2024, 33 (6):  060314.  DOI: 10.1088/1674-1056/ad342b
    Abstract ( 67 )   HTML ( 0 )   PDF (1209KB) ( 25 )  
    Quantum error correction, a technique that relies on the principle of redundancy to encode logical information into additional qubits to better protect the system from noise, is necessary to design a viable quantum computer. For this new topological stabilizer code-$XYZ^{2}$ code defined on the cellular lattice, it is implemented on a hexagonal lattice of qubits and it encodes the logical qubits with the help of stabilizer measurements of weight six and weight two. However topological stabilizer codes in cellular lattice quantum systems suffer from the detrimental effects of noise due to interaction with the environment. Several decoding approaches have been proposed to address this problem. Here, we propose the use of a state-attention based reinforcement learning decoder to decode $XYZ^{2}$ codes, which enables the decoder to more accurately focus on the information related to the current decoding position, and the error correction accuracy of our reinforcement learning decoder model under the optimisation conditions can reach 83.27\% under the depolarizing noise model, and we have measured thresholds of 0.18856 and 0.19043 for $XYZ^{2}$ codes at code spacing of 3-7 and 7-11, respectively. our study provides directions and ideas for applications of decoding schemes combining reinforcement learning attention mechanisms to other topological quantum error-correcting codes.
    Triple points and phase transitions of D-dimensional dyonic AdS black holes with quasitopological electromagnetism in Einstein-Gauss-Bonnet gravity
    Ping-Hui Mou(牟平辉), Qing-Quan Jiang(蒋青权), Ke-Jian He(何柯腱), and Guo-Ping Li(李国平)
    Chin. Phys. B, 2024, 33 (6):  060401.  DOI: 10.1088/1674-1056/ad3342
    Abstract ( 74 )   HTML ( 0 )   PDF (1034KB) ( 84 )  
    By considering the negative cosmological constant $\varLambda$ as a thermodynamic pressure, we study the thermodynamics and phase transitions of the $D$-dimensional dyonic AdS black holes (BHs) with quasitopological electromagnetism in Einstein-Gauss-Bonnet (EGB) gravity. The results indicate that the small/large BH phase transition that is similar to the van der Waals (vdW) liquid/gas phase transition always exists for any spacetime dimensions. Interestingly, we then find that this BH system exhibits a more complex phase structure in 6-dimensional case that is missed in other dimensions. Specifically, it shows for $D=6$ that we observed the small/intermediate/large BH phase transitions in a specific parameter region with the triple point naturally appeared. Moreover, when the magnetic charge turned off, we still observed the small/intermediate/large BH phase transitions and triple point only in 6-dimensional spacetime, which is consistent with the previous results. However, for the dyonic AdS BHs with quasitopological electromagnetism in Einstein-Born-Infeld (EBI) gravity, the novel phase structure composed of two separate coexistence curves observed by Li et al. [ Phys. Rev. D 105 104048 (2022)] disappeared in EGB gravity. This implies that this novel phase structure is closely related to gravity theories, and seems to have nothing to do with the effect of quasitopological electromagnetism. In addition, it is also true that the critical exponents calculated near the critical points possess identical values as mean field theory. Finally, we conclude that these findings shall provide some deep insights into the intriguing thermodynamic properties of the dyonic AdS BHs with quasitopological electromagnetism in EGB gravity.
    Kármán vortex street in a spin-orbit-coupled Bose-Einstein condensate with PT symmetry
    Kai-Hua Shao(邵凯花), Bao-Long Xi(席保龙), Zhong-Hong Xi(席忠红), Pu Tu(涂朴), Qing-Qing Wang(王青青), Jin-Ping Ma(马金萍), Xi Zhao(赵茜), and Yu-Ren Shi(石玉仁)
    Chin. Phys. B, 2024, 33 (6):  060501.  DOI: 10.1088/1674-1056/ad2bf3
    Abstract ( 70 )   HTML ( 0 )   PDF (6519KB) ( 83 )  
    The dynamics of spin-orbit-coupled Bose-Einstein condensate with parity-time symmetry through a moving obstacle potential is simulated numerically. In the miscible two-component condensate, the formation of the Kármán vortex street is observed in one component, while 'the half-quantum vortex street' is observed in the other component. Other patterns of vortex shedding, such as oblique vortex dipoles, V-shaped vortex pairs, irregular turbulence, and combined modes of various wakes, can also be found. The ratio of inter-vortex spacing in one row to the distance between vortex rows is approximately $0.18$, which is less than the stability condition $0.28$ of classical fluid. The drag force acting on the obstacle potential is simulated. The parametric regions of Kármán vortex street and other vortex patterns are calculated. The range of Kármán vortex street is surrounded by the region of combined modes. In addition, spin-orbit coupling disrupts the symmetry of the system and the gain-loss affects the local particle distribution of the system, which leads to the local symmetry breaking of the system, and finally influences the stability of the Kármán vortex street. Finally, we propose an experimental protocol to realize the Kármán vortex street in a system.
    Extensive numerical simulations on competitive growth between the Edwards-Wilkinson and Kardar-Parisi-Zhang universality classes
    Chengzhi Yu(余成志), Xiao Liu(刘潇), Jun Tang(唐军), and Hui Xia(夏辉)
    Chin. Phys. B, 2024, 33 (6):  060502.  DOI: 10.1088/1674-1056/ad322e
    Abstract ( 85 )   HTML ( 0 )   PDF (5537KB) ( 114 )  
    Extensive numerical simulations and scaling analysis are performed to investigate competitive growth between the linear and nonlinear stochastic dynamic growth systems, which belong to the Edwards-Wilkinson (EW) and Kardar-Parisi-Zhang (KPZ) universality classes, respectively. The linear growth systems include the EW equation and the model of random deposition with surface relaxation (RDSR), the nonlinear growth systems involve the KPZ equation and typical discrete models including ballistic deposition (BD), etching, and restricted solid on solid (RSOS). The scaling exponents are obtained in both the ($1+1$)- and ($2+1$)-dimensional competitive growth with the nonlinear growth probability $p$ and the linear proportion $1-p$. Our results show that, when $p$ changes from 0 to 1, there exist non-trivial crossover effects from EW to KPZ universality classes based on different competitive growth rules. Furthermore, the growth rate and the porosity are also estimated within various linear and nonlinear growths of cooperation and competition.
    Effects of asymmetric coupling and boundary on the dynamic behaviors of a random nearest neighbor coupled system
    Ling Xu(徐玲) and Lei Jiang(姜磊)
    Chin. Phys. B, 2024, 33 (6):  060503.  DOI: 10.1088/1674-1056/ad3b86
    Abstract ( 63 )   HTML ( 0 )   PDF (3478KB) ( 79 )  
    This study investigates the dynamical behaviors of nearest neighbor asymmetric coupled systems in a confined space. First, the study derivative analytical stability and synchronization conditions for the asymmetrically coupled system in an unconfined space, which are then validated through numerical simulations. Simulation results show that asymmetric coupling has a significant impact on synchronization conditions. Moreover, it is observed that irrespective of whether the system is confined, an increase in coupling asymmetry leads to a hastened synchronization pace. Additionally, the study examines the effects of boundaries on the system's collective behaviors via numerical experiments. The presence of boundaries ensures the system's stability and synchronization, and reducing these boundaries can expedite the synchronization process and amplify its effects. Finally, the study reveals that the system's output amplitude exhibits stochastic resonance as the confined boundary size increases.
    Two innovative equivalent statements of the third law of thermodynamics
    Xiaohang Chen(陈晓航), Yinghui Zhou(周颖慧), and Jincan Chen(陈金灿)|
    Chin. Phys. B, 2024, 33 (6):  060504.  DOI: 10.1088/1674-1056/ad39c8
    Abstract ( 58 )   HTML ( 0 )   PDF (478KB) ( 22 )  
    It is found from textbooks and literature that there are three different statements for the third law of thermodynamics, i.e., the Nernst theorem, the unattainability statement of absolute zero temperature, and the heat capacity statement. It is pointed out that such three statements correspond to three thermodynamic parameters, which are, respectively, the entropy, temperature, and heat capacity, and can be obtained by extrapolating the experimental results of different parameters at ultra-low temperatures to absolute zero. It is expounded that because there is no need for additional assumptions in the derivation of the Nernst equation, the Nernst theorem should be renamed as the Nernst statement. Moreover, it is proved that both the Nernst statement and the heat capacity statement are mutually deducible and equivalent, while the unattainability of absolute zero temperature is only a corollary of the Nernst statement or the heat capacity statement so that it is unsuitably referred to as one statement of the third law of thermodynamics. The conclusion is that the Nernst statement and the heat capacity statement are two equivalent statements of the third law of thermodynamics.
    Performance optimization of a SERF atomic magnetometer based on flat-top light beam
    Ziqi Yuan(袁子琪), Junjian Tang(唐钧剑), Shudong Lin(林树东), and Yueyang Zhai(翟跃阳)
    Chin. Phys. B, 2024, 33 (6):  060703.  DOI: 10.1088/1674-1056/ad401b
    Abstract ( 127 )   HTML ( 0 )   PDF (787KB) ( 101 )  
    We explore the impact of pumping beams with different transverse intensity profiles on the performance of the spin-exchange relaxation-free (SERF) atomic magnetometers (AMs). We conduct experiments comparing the traditional Gaussian optically-pumped AM with that utilizing the flat-top optically-pumped (FTOP) method. Our findings reveal that the FTOP-based approach outperforms the conventional method, exhibiting a larger response, a narrower magnetic resonance linewidth, and a superior low-frequency noise performance. Specifically, the use of FTOP method leads to a 16% enhancement in average sensitivity within 1Hz-30Hz frequency range. Our research emphasizes the significance of achieving transverse polarization uniformity in AMs, providing insights for future optimization efforts and sensitivity improvements in miniaturized magnetometers.
    ATOMIC AND MOLECULAR PHYSICS
    Manipulating the electron dynamics in the non-sequential double ionization process of Ar atoms by an orthogonal two-color laser field
    Pengzhao Wang(王鹏昭), Lijie Qian(钱丽洁), Zhenrong Sun(孙真荣), and Yan Yang(杨岩)
    Chin. Phys. B, 2024, 33 (6):  063201.  DOI: 10.1088/1674-1056/ad2606
    Abstract ( 83 )   HTML ( 0 )   PDF (3384KB) ( 40 )  
    Electron dynamics during non-sequential double ionization (NSDI) is one of the most attractive areas of research in the field of laser-atom or laser-molecule interaction. Based on the classic two-dimensional model, we study the process of NSDI of argon atoms driven by a few-cycle orthogonal two-color laser field composed of 800nm and 400nm laser pulses. By changing the relative phase of the two laser pulses, a localized enhancement of NSDI yield is observed at 0.5$\pi $ and 1.5$\pi $, which could be attributed to a rapid and substantial increase in the number of electrons returning to the parent ion within extremely short time intervals at these specific phases. Through the analysis of the electron-electron momentum correlations within different time windows of NSDI events and the angular distributions of emitted electrons in different channels, we observe a more pronounced electron-electron correlation phenomenon in the recollision-induced ionization (RII) channel. This is attributed to the shorter delay time in the RII channel.
    Entropy of deterministic trajectory via trajectories ensemble
    Yonggang Peng(彭勇刚), Cuiping Ran(冉翠平), and Yujun Zheng(郑雨军)
    Chin. Phys. B, 2024, 33 (6):  063401.  DOI: 10.1088/1674-1056/ad3348
    Abstract ( 55 )   HTML ( 0 )   PDF (1453KB) ( 23 )  
    We present a formulation of the single-trajectory entropy using the trajectories ensemble. The single-trajectory entropy is affected by its surrounding trajectories via the distribution function. The single-trajectory entropies are studied in two typical potentials, i.e., harmonic potential and double-well potential, and in viscous environment by interacting trajectory method. The results of the trajectory methods are in agreement well with the numerical methods (Monte Carlo simulation and difference equation). The single-trajectory entropies increasing (decreasing) could be caused by absorption (emission) heat from (to) the thermal environment. Also, some interesting trajectories, which correspond to the rare evens in the processes, are demonstrated.
    Optimal preparation of Bose and Fermi atomic gas mixtures of 87Rb and 40K in a crossed optical dipole trap
    Peibo Ding(丁培波), Biao Shan(单标), Yuhang Zhao(赵宇航), Yajing Yang(杨雅婧), Liangchao Chen(陈良超), Zengming Meng(孟增明), Pengjun Wang(王鹏军), and Lianghui Huang(黄良辉)
    Chin. Phys. B, 2024, 33 (6):  063402.  DOI: 10.1088/1674-1056/ad334d
    Abstract ( 59 )   HTML ( 0 )   PDF (1781KB) ( 28 )  
    We report on the optimal production of the Bose and Fermi mixtures with $^{87}$Rb and $^{40}$K in a crossed optical dipole trap (ODT). We measure the atomic number and lifetime of the mixtures in combination of the spin state $|F=9/2, m_{\scriptscriptstyle{\rm F}}=9/2\rangle$ of $^{40}$K and $|1, 1\rangle$ of $^{87}$Rb in the ODT, which is larger and longer compared with the combination of the spin state $|9/2, 9/2\rangle$ of $^{40}$K and $|2, 2\rangle$ of $^{87}$Rb in the ODT. We observe the atomic numbers of $^{87}$Rb and $^{40}$K shown in each stage of the sympathetic cooling process while gradually reducing the depth of the optical trap. By optimizing the relative loading time of atomic mixtures in the MOT, we obtain the large atomic number of $^{40}$K ($\sim6\times10^{6}$) or the mixtures of atoms with an equal number ($\sim1.6\times10^{6}$) at the end of evaporative cooling in the ODT. We experimentally investigate the evaporative cooling in an enlarged volume of the ODT via adding a third laser beam to the crossed ODT and found that more atoms ($8\times10^{6}$) and higher degeneracy ($T/T_{\scriptscriptstyle{\rm F}}=0.25$) of Fermi gases are obtained. The ultracold atomic gas mixtures pave the way to explore phenomena such as few-body collisions and the Bose-Fermi Hubbard model, as well as for creating ground-state molecules of $^{87}$Rb$^{40}$K.
    ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS
    Divergence angle consideration in energy spread measurement for high-quality relativistic electron beam in laser wakefield acceleration
    Guang-Wei Lu(卢光伟), Yao-Jun Li(李曜均), Xi-Chen Hu(胡曦辰), Si-Yu Chen(陈思宇), Hao Xu(徐豪), Ming-Yang Zhu(祝铭阳), Wen-Chao Yan(闫文超), and Li-Ming Chen(陈黎明)
    Chin. Phys. B, 2024, 33 (6):  064101.  DOI: 10.1088/1674-1056/ad2dcb
    Abstract ( 80 )   HTML ( 0 )   PDF (3031KB) ( 63 )  
    The thorough exploration of the transverse quality represented by divergence angle has been lacking yet in the energy spread measurement of the relativistic electron beam for laser wakefield acceleration (LWFA). In this work, we fill this gap by numerical simulations based on the experimental data, which indicate that in a C-shape magnet, magnetic field possesses the beam focusing effect, considering that the divergence angle will result in an increase in the full width at half maxima (FWHM) of the electron density distribution in a uniformly isotropic manner, while the length-to-width ratio decreases. This indicates that the energy spread obtained from the electron deflection distance is smaller than the actual value, regardless of the divergence angle. A promising and efficient way to accurately correct the value is presented by considering the divergence angle (for instance, for an electron beam with a length-to-width ratio of 1.12, the energy spread correct from 1.2% to 1.5%), providing a reference for developing the high-quality electron beam source.
    Robust autofocusing propagation in turbulence
    Na-Na Liu(刘娜娜), Liu Tan(谭柳), Kai-Jian Chen(陈凯健), Pei-Long Hong(洪佩龙), Xiao-Ming Mo(莫小明), Bing-Suo Zou(邹炳锁), Yu-Xuan Ren(任煜轩), and Yi Liang(梁毅)
    Chin. Phys. B, 2024, 33 (6):  064201.  DOI: 10.1088/1674-1056/ad2bf4
    Abstract ( 95 )   HTML ( 0 )   PDF (3658KB) ( 90 )  
    Turbulence in complex environments such as the atmosphere and biological media has always been a great challenge to the application of beam propagation in optical communication, optical trapping and manipulation. To overcome this challenge, this study comprehensively investigates the robust propagation of traditional Gaussian and autofocusing beams in turbulent environments. In order to select stable beams that exhibit high intensity and high field gradient at the focal position in complex environments, Kolmogorov turbulence theory is used to simulate the propagation of beams in atmospheric turbulence based on the multi-phase screen method. We systematically analyze the intensity fluctuations, the variation of the coherence factor and the change in the scintillation index with propagation distance. The analysis reveals that the intensity fluctuations of autofocusing beams are significantly smaller than those of Gaussian beams, and the coherence of autofocusing beams is better than that of Gaussian beams under turbulence. Moreover, autofocusing beams exhibit less oscillation than Gaussian beams, indicating that autofocusing beams propagate in complex environments with less distortion and intensity fluctuation. Overall, this work clearly demonstrates that autofocusing beams exhibit higher stability in propagation compared with Gaussian beams, showing great promise for applications such as optical trapping and manipulation in complex environments.
    Frequency-tunable single-photon router based on a microresonator containing a driven three-level emitter
    Jin-Song Huang(黄劲松), Jing-Lan Hu(胡菁兰), Yan-Ling Li(李艳玲), and Zhong-Hui Xu(徐中辉)
    Chin. Phys. B, 2024, 33 (6):  064202.  DOI: 10.1088/1674-1056/ad362a
    Abstract ( 80 )   HTML ( 0 )   PDF (1189KB) ( 47 )  
    We propose a frequency-tunable router of single photons with high routing efficiency, which is constructed by two waveguides mediately linked by a single-mode whispering gallery resonator with a driven three-level emitter. Quantum routing probability in the output port is obtained via the real-space Hamiltonian. By adjusting the resonator-emitter coupling and the drive, the desired continuous central frequencies for the resonance peaks of routing photons can be manipulated nearly linearly, with the assistance of Rabi splitting effect and optical Stark shift. The proposed routing system may provide potential applications in designing other frequency-modulation quantum optical devices, such as multiplexers, filters, and so on.
    Optical PAM-4/PAM-8 generation via dual-Raman process in Rydberg atoms
    Xiao-Yun Song(宋晓云), Zheng Yin(尹政), Guan-Yu Ren(任冠宇), Ming-Zhi Han(韩明志), Ai-Hong Yang(杨艾红), Yi-Hong Qi(祁义红), and Yan-Dong Peng(彭延东)
    Chin. Phys. B, 2024, 33 (6):  064203.  DOI: 10.1088/1674-1056/ad3344
    Abstract ( 68 )   HTML ( 0 )   PDF (704KB) ( 26 )  
    A scheme of optical four-level pulse amplitude modulation (PAM-4) is proposed based on dual-Raman process in Rydberg atoms. A probe field counter-propagates with a dual-Raman field which drives the ground and the excited states transition, respectively, and the Rydberg transition is driven by a microwave (MW) field. A gain peak appears in the probe transmission and is sensitive to the MW field strength. Optical PAM-4 can be achieved by encoding an MW signal and decoding the magnitude of a probe signal. Simulation results show that the differential nonlinearity and the integral nonlinearity of the proposed scheme can be reduced by 5 times and 6 times, respectively, compared with the counterparts of previous scheme, and the ratio of level separation mismatch is close to the ideal value 1. Moreover, the scheme is extended to optical PAM-8 signal, which may further improve the spectral efficiency.
    Effects of cross-Kerr coupling on transmission spectrum of double-cavity optomechanical system
    Li-Teng Chen(陈立滕), Li-Guo Qin(秦立国), Li-Jun Tian(田立君), Jie-Hui Huang(黄接辉), Nan-Run Zhou(周南润), and Shang-Qing Gong(龚尚庆)
    Chin. Phys. B, 2024, 33 (6):  064204.  DOI: 10.1088/1674-1056/ad2507
    Abstract ( 106 )   HTML ( 0 )   PDF (801KB) ( 132 )  
    We theoretically study the transmission spectrum of the cavity field in a double-cavity optomechanical system with cross-Kerr (CK) effect. The system consists of two tunneling coupling optomechanical cavities with a mechanical resonator as a coupling interface. By doping CK medium into the mechanical resonator, CK couplings between the cavity fields and the mechanical resonator are introduced. We investigate the effects of CK coupling strength on the transmission spectrum of the cavity field, including the transmission rate, nonreciprocity and four-wave mixing (FWM). We find that the transmission spectrum of the probe field can show two obvious transparent windows, which can be widened by increasing the CK coupling strength. For the transmission between the two cavity fields, the perfect nonreciprocity and reciprocity are present and modulated by CK coupling and phase difference between two effective optomechanical couplings. In addition, the effects of the optomechanical and CK couplings on FWM show that the single peak of FWM is split into three symmetrical peaks due to the introduction of the CK effect.
    Intrinsic polarization conversion and avoided-mode crossing in X-cut lithium niobate microrings
    Zelin Tan(谭泽林), Jianfa Zhang(张检发), Zhihong Zhu(朱志宏), Wei Chen(陈伟), Zhengzheng Shao(邵铮铮), Ken Liu(刘肯), and Shiqiao Qin(秦石乔)
    Chin. Phys. B, 2024, 33 (6):  064205.  DOI: 10.1088/1674-1056/ad47b2
    Abstract ( 104 )   HTML ( 0 )   PDF (1078KB) ( 44 )  
    Compared with well-developed free space polarization converters, polarization conversion between TE and TM modes in the waveguide is generally considered to be caused by shape birefringence, like curvature, morphology of waveguide cross section and scattering. Here, we study the polarization conversion mechanism in 1-THz-FSR X-cut lithium niobate microrings with multiple-resonance condition, that is the conversion can be implemented by birefringence of waveguides, which will also introduce an avoided-mode crossing. In the experiment, we find that this mode crossing results in severe suppression of one sideband in local nondegenerate four-wave mixing and disrupts the cascaded four-wave mixing on this side. Simultaneously, we propose one two-dimensional method to simulate the eigenmodes (TE and TM) in X-cut microrings, and the mode crossing point. This work will provide one approach to the design of polarization converters and simulation for monolithic photonics integrated circuits, and may be helpful to the studies of missed temporal dissipative soliton formation in X-cut lithium niobate rings.
    Non-Kramers doublet ground state in a quaternary cubic compound PrRu2In2Zn18 investigated by ultrasonic measurements
    Hua-Yuan Zhang(张化远), Kazuhei Wakiya, Mitsuteru Nakamura, Masahito Yoshizawa, and Yoshiki Nakanish
    Chin. Phys. B, 2024, 33 (6):  064301.  DOI: 10.1088/1674-1056/ad35af
    Abstract ( 65 )   HTML ( 0 )   PDF (1703KB) ( 15 )  
    We performed ultrasonic measurements on a quaternary cubic compound PrRu$_{2}$In$_{2}$Zn$_{18}$ to explore the ground state properties derived from non-Kramers $\Gamma_{3}$ doublet of Pr$^{3+}$. PrRu$_{2}$In$_{2}$Zn$_{18}$ is a quaternary derivative of the ternary compound PrRu$_{2}$Zn$_{20}$ that exhibits a structural phase transition at $T_{\rm S} = 138 $K. In PrRu$_{2}$In$_{2}$Zn$_{18}$, the Zn atoms at the 16$c$ site in PrRu$_{2}$Zn$_{20}$ are selectively replaced by In atoms. A monotonic increase was observed in the temperature dependence of elastic constants $C_{\rm L} = (C_{11}+2C_{12}+4C_{44})/3$ and $C_{\rm T} = (C_{11}-C_{12}+C_{44})/3$ in the temperature range around $T_{\rm S}$ to which an elastic softening was observed in $(C_{11}-C_{12})/2$ for PrRu$_2$Zn$_{20}$. The disappearance of the softening indicates that the structural transition in PrRu$_2$Zn$_{20}$ is suppressed by the substitution of Zn ions by In ones with a larger ionic radius. Alternatively, the $C_{\rm T}$ of PrRu$_{2}$In$_{2}$Zn$_{18}$ exhibits a precursor Curie-type elastic softening toward low temperatures being responsible for the non-Kramers $\Gamma_{3}$ ground state. We discuss the ground state and the evolution of the elastic properties of the different single-crystal samples of PrRu$_{2}$In$_{2}$Zn$_{18}$ grown under different conditions.
    Effect of speed humps on instantaneous traffic emissions in a microscopic model with limited deceleration capacity
    Yu-Chen Hu(胡宇晨), Qi-Lang Li(李启朗), Jun Liu(刘军), Jun-Xia Wang(王君霞), and Bing-Hong Wang(汪秉宏)
    Chin. Phys. B, 2024, 33 (6):  064501.  DOI: 10.1088/1674-1056/ad2608
    Abstract ( 62 )   HTML ( 0 )   PDF (2018KB) ( 64 )  
    As a common transportation facility, speed humps can control the speed of vehicles on special road sections to reduce traffic risks. At the same time, they also cause instantaneous traffic emissions. Based on the classic instantaneous traffic emission model and the limited deceleration capacity microscopic traffic flow model with slow-to-start rules, this paper has investigated the impact of speed humps on traffic flow and the instantaneous emissions of vehicle pollutants in a single lane situation. The numerical simulation results have shown that speed humps have significant effects on traffic flow and traffic emissions. In a free-flow region, the increase of speed humps leads to the continuous rise of CO$_2$, NO$_X$ and PM emissions. Within some density ranges, one finds that these pollutant emissions can evolve into some higher values under some random seeds. Under other random seeds, they can evolve into some lower values. In a wide moving jam region, the emission values of these pollutants sometimes appear as continuous or intermittent phenomenon. Compared to the refined NaSch model, the present model has lower instantaneous emissions such as CO$_2$, NO$_X$ and PM and higher volatile organic components (VOC) emissions. Compared to the limited deceleration capacity model without slow-to-start rules, the present model also has lower instantaneous emissions such as CO$_2$, NO$_X$ and PM and higher VOC emissions in a wide moving jam region. These results can also be confirmed or explained by the statistical values of vehicle velocity and acceleration.
    Morphological analysis for thermodynamics of cavitation collapse near fractal solid wall
    Minglei Shan(单鸣雷), Yu Yang(杨雨), Xuefen Kan(阚雪芬), Cheng Yin(殷澄), and Qingbang Han(韩庆邦)
    Chin. Phys. B, 2024, 33 (6):  064701.  DOI: 10.1088/1674-1056/ad3343
    Abstract ( 69 )   HTML ( 0 )   PDF (5609KB) ( 20 )  
    A fractal geometric boundary with natural wall features is introduced into a hybrid lattice-Boltzmann-method (LBM) multiphase model. The physical model of cavitation bubble collapse near the irregular geometric wall is established to study the thermodynamic characteristics of the bubble collapse. Due to the lack of periodicity, symmetry, spatial uniformity and obvious correlation in the LBM simulation of the bubble collapse near the fractal wall, the morphological analysis based on Minkowski functional is introduced into the thermodynamic investigation of cavitation bubble so as to analyze and obtain the effective information. The results show that the Minkowski functional method can employed to study the temperature information in complex physical fields hierarchically and quantitatively. The high/low temperature region of the cavitation flow is explored, and thermal effect between irregular and fractal geometric wall and cavitation bubble can be revealed. It illustrates that LBM and morphological analysis complement each other, and morphological analysis can also be used as an optional and potential tool in research field of complex multiphase flows.
    On the spreading behavior of a droplet on a circular cylinder using the lattice Boltzmann method
    Fan Yang(杨帆), Hu Jin(金虎), and Mengyao Dai(戴梦瑶)
    Chin. Phys. B, 2024, 33 (6):  064702.  DOI: 10.1088/1674-1056/ad3b7f
    Abstract ( 75 )   HTML ( 0 )   PDF (1822KB) ( 28 )  
    The study of a droplet spreading on a circular cylinder under gravity was carried out using the pseudo-potential lattice Boltzmann high-density ratios multiphase model with a non-ideal Peng-Robinson equation of state. The calculation results indicate that the motion of the droplet on the cylinder can be divided into three stages: spreading, sliding, and aggregating. The contact length and contact time of a droplet on a cylindrical surface can be affected by factors such as the wettability gradient of the cylindrical wall, the Bond number, and droplet size. Furthermore, phase diagrams showing the relationship between Bond number, cylinder wall wettability gradient, and contact time as well as maximum contact length for three different droplet sizes are given. A theoretical foundation for additional research into the heat and mass transfer process between the droplet and the cylinder can be established by comprehending the variable rules of maximum contact length and contact time.
    PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES
    Global dust density in two-dimensional complex plasma
    Yi-Zhen Zhao(赵逸真), Song-Fen Liu(刘松芬), Wei Kong(孔伟), and Fang Yang(杨芳)
    Chin. Phys. B, 2024, 33 (6):  065201.  DOI: 10.1088/1674-1056/ad2a76
    Abstract ( 70 )   HTML ( 0 )   PDF (1214KB) ( 20 )  
    The driven-dissipative Langevin dynamics simulation is used to produce a two-dimensional (2D) dense cloud, which is composed of charged dust particles trapped in a quadratic potential. A 2D mesh grid is built to analyze the center-to-wall dust density. It is found that the local dust density in the outer region relative to that of the inner region is more nonuniform, being consistent with the feature of quadratic potential. The dependences of the global dust density on equilibrium temperature, particle size, confinement strength, and confinement shape are investigated. It is found that the particle size, the confinement strength, and the confinement shape strongly affect the global dust density, while the equilibrium temperature plays a minor effect on it. In the direction where there is a stronger confinement, the dust density gradient is bigger.
    Effects of diamagnetic drift on nonlinear interaction between multi-helicity neoclassical tearing modes
    Haiyuan Wang(王海源), Shuai Jiang(姜帅), Tong Liu(刘桐), Lai Wei(魏来), Qibin Luan(栾其斌), and Zheng-Xiong Wang(王正汹)
    Chin. Phys. B, 2024, 33 (6):  065202.  DOI: 10.1088/1674-1056/ad24d3
    Abstract ( 92 )   HTML ( 0 )   PDF (1759KB) ( 28 )  
    A numerical study of the diamagnetic drift effect on the nonlinear interaction between multi-helicity neoclassical tearing modes (NTMs) is carried out using a set of four-field equations including two-fluid effects. The results show that, in contrast to the single-fluid case, 5/3 NTM cannot be completely suppressed by 3/2 NTM with diamagnetic drift flow. Both modes exhibit oscillation and coexist in the saturated phase. To better understand the effect of the diamagnetic drift flow on multiple-helicity NTMs, the influence of typical relevant parameters is investigated. It is found that the average saturated magnetic island width increases with increasing bootstrap current fraction $f_{\rm b}$ but decreases with the ion skin depth $\delta $. In addition, as the ratio of parallel to perpendicular transport coefficients $\chi_{\parallel }/\chi_{\bot }$ increases, the average saturated magnetic island widths of the 3/2 and 5/3 NTMs increase. The underlying mechanisms behind these observations are discussed in detail.
    Velocity analysis of supersonic jet flow in double-cone ignition scheme
    Zhong-Yuan Zhu(朱仲源), Cheng-Long Zhang(张成龙), and Ying-Jun Li(李英骏)
    Chin. Phys. B, 2024, 33 (6):  065203.  DOI: 10.1088/1674-1056/acc1d4
    Abstract ( 116 )   PDF (1056KB) ( 71 )  
    In the double-cone ignition schemes (DCIS), the deuterium-tritium target shell is ablated and compressed by a high-power nanosecond laser in Au-cones to generate plasmas. Under the actions of spherically symmetric compression and acceleration along the Au cone, they will be ejected out of the cone mouth and collide with each other. The plasmas experience conversion from kinetic energy to internal energy at the vertex of the geometric center of two Au cones that are symmetric to each other, because of which high-density fusion plasmas are preheated. This key physical process has undergone experimental verification on the Shenguang-II upgraded facility in China. Apparently, the improvement and optimization of the velocity of plasmas in hypersonic jet flow at the cone mouth are crucial for the success of the DCIS. In the DCIR7 experiment of the Shenguang-II upgraded facility, a velocity yield of approximately 130-260km/s was achieved for the plasmas at the cone mouth, with a result of nearly 300km/s based on numerical simulation. In this paper, theoretical analysis is performed as regards the process, in which target shells are ablated and compressed by laser to generate high-velocity plasmas ejected through jet flow. Based on this analysis, the formula for the velocity of plasmas in supersonic jet flow at the cone mouth is proposed. This study also provides measures that are more effective for improving the kinetic energy of plasmas and optimizing energy conversion efficiency, which can serve as theoretical references for the adjustment and optimization of processes in subsequent experiments.
    CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES
    Wafer-scale 30° twisted bilayer graphene epitaxially grown on Cu0.75Ni0.25 (111)
    Peng-Cheng Ma(马鹏程), Ao Zhang(张翱), Hong-Run Zhen(甄洪润), Zhi-Cheng Jiang(江志诚), Yi-Chen Yang(杨逸尘), Jian-Yang Ding(丁建阳), Zheng-Tai Liu(刘正太), Ji-Shan Liu(刘吉山), Da-Wei Shen(沈大伟), Qing-Kai Yu(于庆凯), Feng Liu(刘丰), Xue-Fu Zhang(张学富), and Zhong-Hao Liu(刘中灏)
    Chin. Phys. B, 2024, 33 (6):  066101.  DOI: 10.1088/1674-1056/ad2d53
    Abstract ( 85 )   HTML ( 0 )   PDF (4802KB) ( 36 )  
    Twisted bilayer graphene (TBG) has been extensively studied because of its novel physical properties and potential application in electronic devices. Here we report the synthesis and characterization of 30$^\circ$ TBG naturally grown on Cu$_{0.75}$Ni$_{0.25}$ (111) film and investigate the electronic structure by angle-resolved photoemission spectroscopy. Compared with other substrates, our TBG with a wafer scale is acquired with a shorter growth time. The Fermi velocity and energy gap of Dirac cones of TBG are comparable with those of a monolayer on Cu$_{0.85}$Ni$_{0.15}$ (111). The signature of moiré lattices has not been observed in either the low-energy electron diffraction patterns or the Fermi surface map within experimental resolution, possibly due to different Cu and Ni contents in the substrates enhancing the different couplings between the substrate and the first/second layers and hindering the formation of a quasiperiodic structure.
    Pressure-induced magnetic phase and structural transition in SmSb2
    Tao Li(李涛), Shuyang Wang(王舒阳), Xuliang Chen(陈绪亮), Chunhua Chen(陈春华), Yong Fang(房勇), and Zhaorong Yang(杨昭荣)
    Chin. Phys. B, 2024, 33 (6):  066401.  DOI: 10.1088/1674-1056/ad362c
    Abstract ( 67 )   HTML ( 0 )   PDF (1488KB) ( 52 )  
    Motivated by the recent discovery of unconventional superconductivity around a magnetic quantum critical point in pressurized CeSb$_{2}$, here we present a high-pressure study of an isostructural antiferromagnetic (AFM) SmSb$_{2}$ through electrical transport and synchrotron x-ray diffraction measurements. At $P_{\rm C} \sim 2.5 $GPa, we found a pressure-induced magnetic phase transition accompanied by a Cmca, $\to P$4nmm structural phase transition. In the pristine AFM phase below $P_{\rm C}$, the AFM transition temperature of SmSb$_{2}$ is insensitive to pressure; in the emergent magnetic phase above $P_{\rm C}$, however, the magnetic critical temperature increases rapidly with increasing pressure. In addition, at ambient pressure, the magnetoresistivity (MR) of SmSb$_{2}$ increases suddenly upon cooling below the AFM transition temperature and presents linear nonsaturating behavior under high field at 2K. With increasing pressure above $P_{\rm C}$, the MR behavior remains similar to that observed at ambient pressure, both in terms of temperature- and field-dependent MR. This leads us to argue an AFM-like state for SmSb$_{2}$ above $P_{\rm C}$. Within the investigated pressure of up to 45.3GPa and the temperature of down to 1.8K, we found no signature of superconductivity in SmSb$_{2}$.
    Influences of divalent ion substitution on the magnetic and dielectric properties of W-type barium ferrite
    Shiyue He(何诗悦), Ruoshui Liu(刘若水), Xujie Liu(刘煦婕), Xianping Ye(叶先平), Lichen Wang(王利晨), and Baogen Shen(沈保根)
    Chin. Phys. B, 2024, 33 (6):  066801.  DOI: 10.1088/1674-1056/ad39d5
    Abstract ( 76 )   HTML ( 0 )   PDF (1485KB) ( 92 )  
    Saturation magnetization, magneto-crystalline anisotropy field, and dielectric properties are closely related to microwave devices applied at different frequencies. For regulating the magnetic and dielectric properties of W-type barium ferrites, single-phase Ba$Me_{2}$Fe$_{16}$O$_{27}$ ($Me= {\rm Fe}$, Mn, Zn, Ni, Co) with different \textit{Me} ions were synthesized by the high-temperature solid-state method. The saturation magnetization ($M_{\rm s}$) range from 47.77emu/g to 95.34emu/g and the magnetic anisotropy field ($H_{\rm a}$) range from 10700.60Oe (1Oe=79.5775A$\cdot$m$^{-1}$) to 13739.57Oe, depending on the type of cation substitution in the hexagonal lattice. The dielectric permittivity and dielectric loss decrease with increasing frequency of the AC electric field in the low-frequency region, while they almost remain constant in the high-frequency region. The characteristics of easy regulation and preparation make it a potential candidate for use in microwave device applications.
    Superconducting state in Ba(1-x)SrxNi2As2 near the quantum critical point
    Chengfeng Yu(余承峰), Zongyuan Zhang(张宗源), Linxing Song(宋林兴), Yanwei Wu(吴彦玮), Xiaoqiu Yuan(袁小秋), Jie Hou(侯杰), Yubing Tu(涂玉兵), Xingyuan Hou(侯兴元), Shiliang Li(李世亮), and Lei Shan(单磊)
    Chin. Phys. B, 2024, 33 (6):  066802.  DOI: 10.1088/1674-1056/ad334a
    Abstract ( 114 )   HTML ( 0 )   PDF (1532KB) ( 150 )  
    In the phase diagram of the nickel-based superconductor Ba$_{1-x}$Sr$_{x}$Ni$_{2}$As$_{2}$, $T_{\rm c}$ has been found to be enhanced sixfold near the quantum critical point (QCP) $x = 0.71$ compared with the parent compound. However, the mechanism is still under debate. Here, we report a detailed investigation of the superconducting properties near the QCP ($x \approx 0.7$) by utilizing scanning tunneling microscopy and spectroscopy. The temperature-dependent superconducting gap and magnetic vortex state were obtained and analyzed in the framework of the Bardeen-Cooper-Schrieffer model. The ideal isotropic s-wave superconducting gap excludes the long-speculated nematic fluctuations while preferring strong electron-phonon coupling as the mechanism for $T_{\rm c}$ enhancement near the QCP. The lower than expected gap ratio of $\varDelta /(k_{\rm B}T_{\rm c})$ is rooted in the fact that Ba$_{1-x}$Sr$_{x}$Ni$_{2}$As$_{2 }$ falls into the dirty limit with a serious pair breaking effect similar to the parent compound.
    CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
    Magnetism, heat capacity, magnetocaloric effect, and magneto-transport properties of heavy fermion antiferromagnet CeGaSi
    Li-Bo Zhang(张黎博), Qing-Xin Dong(董庆新), Jian-Li Bai(白建利), Qiao-Yu Liu(刘乔宇), Jing-Wen Cheng(程靖雯), Cun-Dong Li(李存东), Pin-Yu Liu(刘品宇), Ying-Rui Sun(孙英睿), Yu Huang(黄宇), Zhi-An Ren(任治安), and Gen-Fu Chen(陈根富)
    Chin. Phys. B, 2024, 33 (6):  067101.  DOI: 10.1088/1674-1056/ad3060
    Abstract ( 99 )   HTML ( 0 )   PDF (3544KB) ( 78 )  
    We synthesize high-quality single crystal of CeGaSi by a Ga self-flux method and investigate its physical properties through magnetic susceptibility, specific heat and electrical resistivity measurements as well as high pressure effect. Magnetic measurements reveal that an antiferromagnetic order develops below $T_{\rm m} \sim 10.4 $K with magnetic moments orientated in the \textit{ab} plane. The enhanced electronic specific heat coefficient and the negative logarithmic slope in the resistivity of CeGaSi indicate that the title compound belongs to the family of Kondo system with heavy fermion ground states. The max magnetic entropy change $-\Delta S_{\mathrm{M}}^{\mathrm{\max}}$ ($\mu_{0}H\bot c$, $\mu_0 H = 7$T) around $T_{\rm m}$ is found to reach up to 11.85J$\cdot$kg$^{-1}$$\cdot$K$^{-1}$. Remarkably, both the antiferromagnetic transition temperature and $-\ln T$ behavior increase monotonically with pressure applied to 20kbar (1bar$=$10$^5$Pa), indicating that much higher pressure will be needed to reach its quantum critical point.
    Discovery of controllable high Chern number quantum anomalous Hall state in tetragonal lattice FeSIn
    Xiao-Lang Ren(任小浪) and Chang-Wen Zhang(张昌文)
    Chin. Phys. B, 2024, 33 (6):  067102.  DOI: 10.1088/1674-1056/ad2bf1
    Abstract ( 71 )   HTML ( 0 )   PDF (2810KB) ( 68 )  
    Quantum anomalous Hall (QAH) insulators have excellent properties driven by fancy topological physics, but their practical application is greatly hindered by the observed temperature of liquid nitrogen, and the QAH insulator with high Chern number is conducive to spintronic devices with lower energy consumption. Here, we find that monolayer FeSIn is a good candidate for realizing the QAH phase; it exhibits a high magnetic transition temperature of 221K and tunable $C = \pm 2$ with respect to magnetization orientation in the $y$-$z$ plane. After the application of biaxial strain, the magnetic axis shifts from the $x$-$y$ plane to the $z$ direction, and the effect of the high $C $ and ferromagnetic ground state on the stress is robust. Also, the effect of correlation $U$ on $C$ has been examined. These properties are rooted in the large size of the Fe atom that contributes to ferromagnetic kinetic exchange with neighboring Fe atoms. These findings demonstrate monolayer FeSIn to be a major template for probing novel QAH devices at higher temperatures.
    Consistency between domain wall oscillation modes and spin wave modes in nanostrips
    Xinwei Dong(董新伟) and Zhenjiang Wu(吴振江)
    Chin. Phys. B, 2024, 33 (6):  067502.  DOI: 10.1088/1674-1056/ad2a6b
    Abstract ( 67 )   HTML ( 0 )   PDF (947KB) ( 22 )  
    Investigations on domain wall (DW) and spin wave (SW) modes in a series of nanostrips with different widths and thicknesses have been carried out using micromagnetic simulation. The simulation results show that the frequencies of SW modes and the corresponding DW modes are consistent with each other if they have the same node number along the width direction. This consistency is more pronounced in wide and thin nanostrips, favoring the DW motion driven by SWs. Further analysis of the moving behavior of a DW driven by SWs is also carried out. The average DW speed can reach a larger value of $\sim 140 $m/s under two different SW sources. We argue that this study is very meaningful for the potential application of DW motion driven by SWs.
    Low-energy spin dynamics in a Kitaev material Na3Ni2BiO6 investigated by nuclear magnetic resonance
    Xinyu Shi(史昕雨), Yi Cui(崔祎), Yanyan Shangguan(上官艳艳), Xiaoyu Xu(徐霄宇), Zhanlong Wu(吴占龙), Ze Hu(胡泽), Shuo Li(李硕), Kefan Du(杜柯帆), Ying Chen(陈颖), Long Ma(马龙), Zhengxin Liu(刘正鑫), Jinsheng Wen(温锦生), Jinshan Zhang(张金珊), and Weiqiang Yu(于伟强)
    Chin. Phys. B, 2024, 33 (6):  067601.  DOI: 10.1088/1674-1056/ad3dce
    Abstract ( 62 )   HTML ( 0 )   PDF (1760KB) ( 40 )  
    We perform $^{23}$Na nuclear magnetic resonance (NMR) and magnetization measurements on an $S = 1$, quasi-2D honeycomb lattice antiferromagnet Na$_3$Ni$_2$BiO$_6$. A large positive Curie-Weiss constant of 22.9K is observed. The NMR spectra at low fields are consistent with a zigzag magnetic order, indicating a large easy-axis anisotropy. With the field applied along the $c^{*}$ axis, the NMR spectra confirm the existence of a $1/3$-magnetization plateau phase between 5.1T and 7.1T. The transition from the zigzag order to the $1/3$-magnetization plateau phase is also found to be a first-order type. A monotonic decrease of the spin gap is revealed in the $1/3$-magnetization plateau phase, which reaches zero at a quantum critical field $H_{\rm C}\approx8.35$T before entering the fully polarized phase. These data suggest the existence of exchange frustration in the system along with strong ferromagnetic interactions, hosting the possibility for Kitaev physics. Besides, well below the ordered phase, the 1/$T_1$ at high fields shows either a level off or an enhancement upon cooling below 3K, which suggests the existence of low-energy fluctuations.
    Observing ferroelastic switching in Hf0.5Zr0.5O2 thin film
    Zhao Guan(关赵), Tao Wang(王陶), Yunzhe Zheng(郑赟喆), Yue Peng(彭悦), Luqi Wei(魏鹿奇), Yuke Zhang(张宇科), Abliz Mattursun(阿卜力孜cdot麦提图尔荪), Jiahao Huang(黄家豪), Wen-Yi Tong(童文旖), Genquan Han(韩根全), Binbin Chen(陈斌斌), Ping-Hua Xiang(向平华), Chun-Gang Duan(段纯刚), and Ni Zhong(钟妮)
    Chin. Phys. B, 2024, 33 (6):  067701.  DOI: 10.1088/1674-1056/ad362f
    Abstract ( 104 )   HTML ( 0 )   PDF (1740KB) ( 47 )  
    Hafnium zirconium oxides (HZO), which exhibit ferroelectric properties, are promising materials for nanoscale device fabrication due to their high complementary metal-oxide-semiconductor (CMOS) compatibility. In addition to piezoelectricity, ferroelectricity, and flexoelectricity, this study reports the observation of ferroelasticity using piezoelectric force microscopy (PFM) and scanning transmission electron microscopy (STEM). The dynamics of 90$^\circ$ ferroelastic domains in HZO thin films are investigated under the influence of an electric field. Switching of the retentive domains is observed through repeated wake-up measurements. This study presents a possibility of enhancing polarization in HZO thin films during wake-up processes.
    INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY
    Linear dichroism transition and polarization-sensitive photodetector of quasi-one-dimensional palladium bromide
    Wan-Li Zhu(朱万里), Wei-Li Zhen(甄伟立), Rui Niu(牛瑞), Ke-Ke Jiao(焦珂珂), Zhi-Lai Yue(岳智来), Hui-Jie Hu(胡慧杰), Fei Xue(薛飞), and Chang-Jin Zhang(张昌锦)
    Chin. Phys. B, 2024, 33 (6):  068101.  DOI: 10.1088/1674-1056/ad36ba
    Abstract ( 98 )   HTML ( 0 )   PDF (2913KB) ( 89 )  
    Perpendicular optical reversal of the linear dichroism transition has promising applications in polarization-sensitive optoelectronic devices. We perform a systematical study on the in-plane optical anisotropy of quasi-one-dimensional PdBr$_{2}$ by using combined measurements of the angle-resolved polarized Raman spectroscopy (ARPRS) and anisotropic optical absorption spectrum. The analyses of ARPRS data validate the anisotropic Raman properties of the PdBr$_{2}$ flake. And anisotropic optical absorption spectrum of PdBr$_{2}$ nanoflake demonstrates distinct optical linear dichroism reversal. Photodetector constructed by PdBr$_{2}$ nanowire exhibits high responsivity of 747A$\cdot$W$^{-1}$ and specific detectivity of 5.8$\times10^{12}$Jones. And the photodetector demonstrates prominent polarization-sensitive photoresponsivity under 405-nm light irradiation with large photocurrent anisotropy ratio of 1.56, which is superior to those of most of previously reported quasi-one-dimensional counterparts. Our study offers fundamental insights into the strong optical anisotropy exhibited by PdBr$_{2}$, establishing it as a promising candidate for miniaturization and integration trends of polarization-related applications.
    Synthesis and nitrogen content regulation of diamond in a high-pressure hydrogen-rich environment
    Guofeng Huang(黄国锋), Liangchao Chen(陈良超), and Chao Fang(房超)
    Chin. Phys. B, 2024, 33 (6):  068102.  DOI: 10.1088/1674-1056/ad2a6d
    Abstract ( 86 )   HTML ( 0 )   PDF (1155KB) ( 63 )  
    The regulating nitrogen content of diamond in a hydrogen-rich high-temperature and high-pressure (HPHT) growth environment was systematically investigated in this work by developing three growth systems, namely, "FeNi$+$Ti", "FeNi$+$C$_{3}$N$_{6}$H$_{6}$", and "FeNi$+$Ti$+$C$_{3}$N$_{6}$H$_{6}$". Optical microscopy, infrared spectroscopy, and photoluminescence (PL) spectroscopy measurements were conducted to analyze the spectroscopic characteristics of diamonds grown in these three systems. From our analysis, it was demonstrated that the presence of hydrogen in the sp$^{3}$ hybrid C-H does not directly affect the color of the diamond and facilitates the increase of the nitrogen-vacancy (NV) center concentration in a high-nitrogen-content diamond. In addition, titanium plays an important role in nitrogen removal, while its impact on hydrogen doping within the diamond lattice is insignificant. Most importantly, by regulating the ratio of nitrogen impurities that coexist in the nitrogen and hydrogen HPHT environment, the production of hydrogenous IIa-type diamond, hydrogenous Ib-type diamond, and hydrogenous high-nitrogen-type diamonds was achieved with a nitrogen content of less than 1ppm to 1600ppm.
    Effect of trace oxygen on plasma nitriding of titanium foil
    Hai-Tao Zhou(周海涛), Xi-Ya Xiong(熊希雅), Ke-Xin Ma(马可欣), Bing-Wei Luo(罗炳威), Fei Luo(罗飞), and Cheng-Min Shen(申承民)
    Chin. Phys. B, 2024, 33 (6):  068103.  DOI: 10.1088/1674-1056/ad35b0
    Abstract ( 77 )   HTML ( 0 )   PDF (1233KB) ( 38 )  
    Titanium nitride films are prepared by plasma enhanced chemical vapor deposition method on titanium foil using N$_{2}$ as precursor. In order to evaluate the effect of oxygen on the growth of titanium nitride films, a small amount of O$_{2}$ is introduced into the preparation process. The study indicates that trace O$_{2}$ addition into the reaction chamber gives rise to significant changes on the color and micro-morphology of the foil, featuring dense and long nano-wires. The as-synthesized nanostructures are characterized by various methods and identified as TiN, Ti$_{2}$N, and TiO$_{2}$ respectively. Moreover, the experiment results show that oxide nanowire has a high degree of crystallinity and the nitrides present specific orientation relationships with the titanium matrix.
    Bimodal growth of Fe islands on graphene
    Yi-Sheng Gu(顾翊晟), Qiao-Yan Yu(俞俏滟), Dang Liu(刘荡), Ji-Ce Sun(孙蓟策), Rui-Jun Xi(席瑞骏), Xing-Sen Chen(陈星森), Sha-Sha Xue(薛莎莎), Yi Zhang(章毅), Xian Du(杜宪), Xu-Hui Ning(宁旭辉), Hao Yang(杨浩), Dan-Dan Guan(管丹丹), Xiao-Xue Liu(刘晓雪), Liang Liu(刘亮), Yao-Yi Li(李耀义), Shi-Yong Wang(王世勇), Can-Hua Liu(刘灿华), Hao Zheng(郑浩), and Jin-Feng Jia(贾金锋)
    Chin. Phys. B, 2024, 33 (6):  068104.  DOI: 10.1088/1674-1056/ad322f
    Abstract ( 264 )   HTML ( 1 )   PDF (1707KB) ( 118 )  
    Magnetic metals deposited on graphene hold the key to applications in spintronics. Here, we present the results of Fe islands grown on graphene/SiC(0001) by molecular beam epitaxy, which are investigated by scanning tunneling microscopy. The two types of islands distinguished by flat or round tops are revealed, indicating bimodal growth of Fe. The atomic structures on the top surfaces of flat islands are also clearly resolved. Our results may improve the understanding of the mechanisms of metals deposited on graphene and pave the way for future spintronic applications of Fe/graphene systems.
    A pressure-sensitive rheological origin of high friction angles of granular matter observed in NASA-MGM project
    Xiaohui Cheng(程晓辉), Shize Xiao(肖世泽), Sen Yang(杨森), Naifeng Zhao(赵乃峰), and Alex Sixie Cao
    Chin. Phys. B, 2024, 33 (6):  068301.  DOI: 10.1088/1674-1056/ad3b88
    Abstract ( 58 )   HTML ( 1 )   PDF (719KB) ( 84 )  
    An abnormally high peak friction angle of Ottawa sand was observed in (National Aeronautics and Space Administration) NASA-(Mechanics of Granular Materials) MGM tests in microgravity conditions on the space shuttle. Previous investigations have been unsuccessful in providing a constitutive insight into this behavior of granular materials under extremely low effective stress conditions. Here, a recently proposed unified constitutive model for transient rheological behavior of sand and other granular materials is adopted for the analytical assessment of high peak friction angles. For the first time, this long-eluded behavior of sand is attributed to a hidden rheological transition mechanism, that is not only rate-sensitive, but also pressure-sensitive. The NASA-MGM microgravity conditions show that shear-tests of sand can be performed under abnormally low confining stress conditions. The pressure-sensitive behavior of granular shearing that is previously ignored is studied based on the $\mu (I)$ rheology and its variations. Comparisons between the model and the NASA microgravity tests demonstrate a high degree of agreement. The research is highly valid for pressure-sensitive and rate-dependent problems that occur during earthquakes, landslides, and space exploration.
    One memristor-one electrolyte-gated transistor-based high energy-efficient dropout neuronal units Hot!
    Yalin Li(李亚霖), Kailu Shi(时凯璐), Yixin Zhu(朱一新), Xiao Fang(方晓), Hangyuan Cui(崔航源), Qing Wan(万青), and Changjin Wan(万昌锦)
    Chin. Phys. B, 2024, 33 (6):  068401.  DOI: 10.1088/1674-1056/ad39d6
    Abstract ( 105 )   HTML ( 0 )   PDF (923KB) ( 127 )  
    Artificial neural networks (ANN) have been extensively researched due to their significant energy-saving benefits. Hardware implementations of ANN with dropout function would be able to avoid the overfitting problem. This letter reports a dropout neuronal unit (1R1T-DNU) based on one memristor-one electrolyte-gated transistor with an ultralow energy consumption of 25pJ/spike. A dropout neural network is constructed based on such a device and has been verified by MNIST dataset, demonstrating high recognition accuracies ($> 90$%) within a large range of dropout probabilities up to 40%. The running time can be reduced by increasing dropout probability without a significant loss in accuracy. Our results indicate the great potential of introducing such 1R1T-DNUs in full-hardware neural networks to enhance energy efficiency and to solve the overfitting problem.
    Rational molecular engineering towards efficient heterojunction solar cells based on organic molecular acceptors
    Kaiyan Zhang(张凯彦), Peng Song(宋朋), Fengcai Ma(马凤才), and Yuanzuo Li(李源作)
    Chin. Phys. B, 2024, 33 (6):  068402.  DOI: 10.1088/1674-1056/ad2a6a
    Abstract ( 60 )   HTML ( 0 )   PDF (2156KB) ( 68 )  
    The selection of photoactive layer materials for organic solar cells (OSCs) is essential for the photoelectric conversion process. It is well known that chlorophyll is an abundant pigment in nature and is extremely valuable for photosynthesis. However, there is little research on how to improve the efficiency of chlorophyll-based OSCs by matching chlorophyll derivatives with excellent non-fullerene acceptors to form heterojunctions. Therefore in this study we utilize a chlorophyll derivative, Ce$_6$Me$_3$, as a donor material and investigate the performance of its heterojunction with acceptor materials. Through density functional theory, the photoelectric performances of acceptors, including the fullerene derivative PC$_{71}$BM and the terminal halogenated non-fullerene DTBCIC series, are compared in detail. It is found that DTBCIC-Cl has better planarity, light absorption, electron affinity, charge reorganization energy and charge mobility than others. Ce$_6$Me$_3$ has good energy level matching and absorption spectral complementarity with the investigated acceptor molecules and also shows good electron donor properties. Furthermore, the designed Ce$_6$Me$_3$/DTBCIC interfaces have improved charge separation and reorganization rates ($K_{\rm CS}/K_{\rm CR}$) compared with the Ce$_6$Me$_3$/PC$_{71}$BM interface. This research provides a theoretical basis for the design of photoactive layer materials for chlorophyll-based OSCs.
    Optimize Purcell filter design for reducing influence of fabrication variation
    Xiao Cai(蔡晓), Yi-Biao Zhou(周翼彪), Wen-Long Yu(于文龙), Kang-Lin Xiong(熊康林), and Jia-Gui Feng(冯加贵)
    Chin. Phys. B, 2024, 33 (6):  068501.  DOI: 10.1088/1674-1056/ad3345
    Abstract ( 84 )   HTML ( 0 )   PDF (911KB) ( 35 )  
    To protect superconducting qubits and enable rapid readout, optimally designed Purcell filters are essential. To suppress the off-resonant driving of untargeted readout resonators, individual Purcell filters are used for each readout resonator. However, achieving consistent frequency between a readout resonator and a Purcell filter is a significant challenge. A systematic computational analysis is conducted to investigate how fabrication variation affects filter performance, through focusing on the coupling capacitor structure and coplanar waveguide (CPW) transmission line specifications. The results indicate that the T-type enclosing capacitor (EC), which exhibits lower structural sensitivity, is more advantageous for achieving target capacitance than the C-type EC and the interdigital capacitor (IDC). By utilizing a large-sized CPW with the T-type EC structure, fluctuations in the effective coupling strength can be reduced to 10%, given typical micro-nanofabrication variances. The numerical simulations presented in this work minimize the influence of fabrication deviations, thereby significantly improving the reliability of Purcell filter designs.
    Fully spin-polarized, valley-polarized and spin-valley-polarized electron beam splitters utilizing zero-line modes in a three-terminal device
    Xiao-Long Lü(吕小龙), Jia-En Yang(杨加恩), and Hang Xie(谢航)
    Chin. Phys. B, 2024, 33 (6):  068502.  DOI: 10.1088/1674-1056/ad2609
    Abstract ( 80 )   HTML ( 1 )   PDF (3438KB) ( 66 )  
    Topological zero-line modes (ZLMs) with spin and valley degrees of freedom give rise to spin, valley and spin-valley transport, which support a platform for exploring quantum transport physics and potential applications in spintronic/valleytronic devices. In this work, we investigate the beam-splitting behaviors of the charge current due to the ZLMs in a three-terminal system. We show that with certain combinations of ZLMs, the incident charge current along the interface between different topological phases can be divided into different polarized currents with unit transmittance in two outgoing terminals. As a result, fully spin-polarized, valley-polarized and spin-valley-polarized electron beam splitters are generated. The mechanism of these splitters is attributed to the cooperative effects of the distribution of the ZLMs and the intervalley and intravalley scatterings that are modulated by the wave-vector mismatch and group velocity mismatch. Interestingly, half-quantized transmittance of these scatterings is found in a fully spin-valley-polarized electron beam splitter. Furthermore, the results indicate that these splitters can be applicable to graphene, silicene, germanene and stanene due to their robustness against the spin-orbit coupling. Our findings offer a new way to understand the transport mechanism and investigate the promising applications of ZLMs.
    Factors resisting protein adsorption on hydrophilic/hydrophobic self-assembled monolayers terminated with hydrophilic hydroxyl groups
    Dangxin Mao(毛党新), Yuan-Yan Wu(吴园燕), and Yusong Tu(涂育松)
    Chin. Phys. B, 2024, 33 (6):  068701.  DOI: 10.1088/1674-1056/ad39ca
    Abstract ( 80 )   HTML ( 0 )   PDF (2173KB) ( 93 )  
    The hydroxyl-terminated self-assembled monolayer (OH-SAM), as a surface resistant to protein adsorption, exhibits substantial potential in applications such as ship navigation and medical implants, and the appropriate strategies for designing anti-fouling surfaces are crucial. Here, we employ molecular dynamics simulations and alchemical free energy calculations to systematically analyze the factors influencing resistance to protein adsorption on the SAMs terminated with single or double OH groups at three packing densities ($\varSigma = 2.0 $nm$^{-2}$, 4.5nm$^{-2}$, and 6.5nm$^{-2}$), respectively. For the first time, we observed that the compactness and order of interfacial water enhance its physical barrier effect, subsequently enhancing the resistance of SAM to protein adsorption. Notably, the spatial hindrance effect of SAM leads to the embedding of protein into SAM, resulting in a lack of resistance of SAM towards protein. Furthermore, the number of hydroxyl groups per unit area of double OH-terminated SAM at $\varSigma = 6.5 $nm$^{-2}$ is approximately 2 to 3 times that of single OH-terminated SAM at $\varSigma = 6.5 $nm$^{-2}$ and 4.5nm$^{-2}$, consequently yielding a weaker resistance of double OH-terminated SAM towards protein. Meanwhile, due to the structure of SAM itself, i.e., the formation of a nearly perfect ice-like hydrogen bond structure, the SAM exhibits the weakest resistance towards protein. This study will complement and improve the mechanism of OH-SAM resistance to protein adsorption, especially the traditional barrier effect of interfacial water.
    Coexisting fast-slow dendritic traveling waves in a 3D-array electric field coupled neuronal network
    Xile Wei(魏熙乐), Zeyu Ren(任泽宇), Meili Lu(卢梅丽), Yaqin Fan(樊亚琴), and Siyuan Chang(常思远)
    Chin. Phys. B, 2024, 33 (6):  068702.  DOI: 10.1088/1674-1056/ad3228
    Abstract ( 62 )   HTML ( 0 )   PDF (3947KB) ( 70 )  
    Coexistence of fast and slow traveling waves without synaptic transmission has been found in hhhippocampal tissues, which is closely related to both normal brain activity and abnormal neural activity such as epileptic discharge. However, the propagation mechanism behind this coexistence phenomenon remains unclear. In this paper, a three-dimensional electric field coupled hippocampal neural network is established to investigate generation of coexisting spontaneous fast and slow traveling waves. This model captures two types of dendritic traveling waves propagating in both transverse and longitude directions: the N-methyl-D-aspartate (NMDA)-dependent wave with a speed of about 0.1m/s and the Ca-dependent wave with a speed of about 0.009m/s. These traveling waves are synaptic-independent and could be conducted only by the electric fields generated by neighboring neurons, which are basically consistent with the in vitro data measured experiments. It is also found that the slow Ca wave could trigger generation of fast NMDA waves in the propagation path of slow waves whereas fast NMDA waves cannot affect the propagation of slow Ca waves. These results suggest that dendritic Ca waves could acted as the source of the coexistence fast and slow waves. Furthermore, we also confirm the impact of cellular spacing heterogeneity on the onset of coexisting fast and slow waves. The local region with decreasing distances among neighbor neurons is more liable to promote the onset of spontaneous slow waves which, as sources, excite propagation of fast waves. These modeling studies provide possible biophysical mechanisms underlying the neural dynamics of spontaneous traveling waves in brain tissues.
    CORRIGENDUM
    Corrigendum to "Numerical studies of atomic three-step photoionization processes with non-monochromatic laser fields"
    Xiaoyong Lu(卢肖勇), Lide Wang(王立德), and Yunfei Li(李云飞)
    Chin. Phys. B, 2024, 33 (6):  069901.  DOI: 10.1088/1674-1056/ad4d66
    Abstract ( 52 )   HTML ( 0 )   PDF (910KB) ( 15 )  
    The Eq.(6) about the time correlation function of the chaotic field model is corrected, along with the corresponding statement. The enlargement factors of $\rho_{33,\rm B}$ and $\rho_{\rm ion,B}$ in the legends of Figs.2(b), 2(c) and 2(d) are corrected. These corrections do not affect the conclusions of the work [Chin. Phys. B 31 063203 (2022)].
ISSN 1674-1056   CN 11-5639/O4
, Vol. 33, No. 6

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