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2024年, 第33卷, 第1期　刊出日期：2023-12-13 上一期    下一期

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Valley filtering and valley-polarized collective modes in bulk graphene monolayers Jian-Long Zheng(郑建龙) and Feng Zhai(翟峰) 2024 (1):  17203-17203.  doi: 10.1088/1674-1056/acfd17 摘要 ( 180 )   HTML ( 8 )   PDF(2372KB) ( 331 )   The presence of two sublattices in hexagonal graphene brings two energetically degenerate extremes in the conduction and valence bands, which are identified by the valley quantum number. Recently, this valley degree of freedom has been suggested to encode and process information, which develops a new carbon-based electronics named graphene valleytronics. In this topical review, we present and discuss valley-related transport properties in bulk graphene monolayers, which are due to strain-induced pseudomagnetic fields and associated vector potential, sublattice-stagger potential, and the valley-Zeeman effect. These valley-related interactions can be utilized to obtain valley filtering, valley spatial separation, valley-resolved guiding modes, and valley-polarized collective modes such as edge or surface plasmons. The present challenges and the perspectives on graphene valleytronics are also provided in this review. 参考文献 | 相关文章 | 计量指标

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Recent progress on valley polarization and valley-polarized topological states in two-dimensional materials Fei Wang(王斐), Yaling Zhang(张亚玲), Wenjia Yang(杨文佳), Huisheng Zhang(张会生), and Xiaohong Xu(许小红) 2024 (1):  17306-17306.  doi: 10.1088/1674-1056/ad0713 摘要 ( 205 )   HTML ( 19 )   PDF(1820KB) ( 297 )   Valleytronics, using valley degree of freedom to encode, process, and store information, may find practical applications in low-power-consumption devices. Recent theoretical and experimental studies have demonstrated that two-dimensional (2D) honeycomb lattice systems with inversion symmetry breaking, such as transition-metal dichalcogenides (TMDs), are ideal candidates for realizing valley polarization. In addition to the optical field, lifting the valley degeneracy of TMDs by introducing magnetism is an efficient way to manipulate the valley degree of freedom. In this paper, we first review the recent progress on valley polarization in various TMD-based systems, including magnetically doped TMDs, intrinsic TMDs with both inversion and time-reversal symmetry broken, and magnetic TMD heterostructures. When topologically nontrivial bands are empowered into valley-polarized systems, valley-polarized topological states, namely valley-polarized quantum anomalous Hall effect can be realized. Therefore, we have also reviewed the theoretical proposals for realizing valley-polarized topological states in 2D honeycomb lattices. Our paper can help readers quickly grasp the latest research developments in this field. 参考文献 | 相关文章 | 计量指标

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Progress on two-dimensional ferrovalley materials Ping Li(李平), Bang Liu(刘邦), Shuai Chen(陈帅), Wei-Xi Zhang(张蔚曦), and Zhi-Xin Guo(郭志新) 2024 (1):  17505-17505.  doi: 10.1088/1674-1056/acf65f 摘要 ( 201 )   HTML ( 2 )   PDF(2806KB) ( 130 )   The electron's charge and spin degrees of freedom are at the core of modern electronic devices. With the in-depth investigation of two-dimensional materials, another degree of freedom, valley, has also attracted tremendous research interest. The intrinsic spontaneous valley polarization in two-dimensional magnetic systems, ferrovalley material, provides convenience for detecting and modulating the valley. In this review, we first introduce the development of valleytronics. Then, the valley polarization forms by the p-, d-, and f-orbit that are discussed. Following, we discuss the investigation progress of modulating the valley polarization of two-dimensional ferrovalley materials by multiple physical fields, such as electric, stacking mode, strain, and interface. Finally, we look forward to the future developments of valleytronics. 参考文献 | 相关文章 | 计量指标

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Valley transport in Kekulé structures of graphene Juan-Juan Wang(王娟娟) and Jun Wang(汪军) 2024 (1):  17801-17801.  doi: 10.1088/1674-1056/acf9e3 摘要 ( 189 )   HTML ( 2 )   PDF(2154KB) ( 145 )   Valleytronics is an emergent discipline in condensed matter physics and offers a new way to encode and manipulate information based on the valley degree of freedom in materials. Among the various materials being studied, Kekulé distorted graphene has emerged as a promising material for valleytronics applications. Graphene can be artificially distorted to form the Kekulé structures rendering the valley-related interaction. In this work, we review the recent progress of research on Kekulé structures of graphene and focus on the modified electronic bands due to different Kekulé distortions as well as their effects on the transport properties of electrons. We systematically discuss how the valley-related interaction in the Kekulé structures was used to control and affect the valley transport including the valley generation, manipulation, and detection. This article summarizes the current challenges and prospects for further research on Kekulé distorted graphene and its potential applications in valleytronics. 参考文献 | 相关文章 | 计量指标

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Optical spectrum of ferrovalley materials: A case study of Janus H-VSSe Chao-Bo Luo(罗朝波), Wen-Chao Liu(刘文超), and Xiang-Yang Peng(彭向阳) 2024 (1):  16303-16303.  doi: 10.1088/1674-1056/acf660 摘要 ( 133 )   HTML ( 1 )   PDF(985KB) ( 107 )   As opposed to the prototypical MoS2 with centroasymmetry, Janus ferrovalley materials such as H-VSSe are less symmetric with the mirror symmetry and time reversal symmetry broken, and hence possess spontaneous valley polarization and strong ferroelasticity. The optical transition is an important means to excite the valley carriers. We investigate the optical spectrum of H-VSSe by using the many-body perturbation-based GW approach and solving the Bethe—Salpeter equation (BSE) to include the electron—hole interactions. It is found that after the GW correction, the band gaps of the quasiparticle bands are much larger than those obtained by the normal density functional theory. The system is ferromagnetic and the valley gaps become non-degenerate due to spin—orbit coupling (SOC). The position of the lowest BSE peak is much lower than the quasiparticle band gap, indicating that the excitonic effect is large. The peak is split into two peaks by the SOC. The binding energy difference between these two BSE peaks is about the same as the difference between the inequivalent valley gaps. Our results show that in Janus H-VSSe the two lowest exciton peaks are from the two inequivalent valleys with different gaps, in contrast to the A and B exciton peaks of MoS2 which are from the same valley. 参考文献 | 相关文章 | 计量指标

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Valley-dependent transport in a mescoscopic twisted bilayer graphene device Wen-Xuan Shi(史文萱), Han-Lin Liu(刘翰林), and Jun Wang(汪军) 2024 (1):  17205-17205.  doi: 10.1088/1674-1056/acf9e4 摘要 ( 155 )   HTML ( 10 )   PDF(537KB) ( 98 )   We study the valley-dependent electron transport in a four-terminal mesoscopic device of the two monolayer graphene nanoribbons vertically stacked together, where the intersection forms a bilayer graphene lattice with a controllable twist angle. Using a tight-binding lattice model, we show that the longitudinal and transverse conductances exhibit significant valley polarization in the low energy regime for small twist angles. As the twist angle increases, the valley polarization shifts to the high energy regime. This arises from the regrouping effect of the electron band in the twisted bilayer graphene region. But for relatively large twist angles, no significant valley polarization is observed. These results are consistent with the spectral densities of the twisted bilayer graphene. 参考文献 | 相关文章 | 计量指标

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Valleytronic topological filters in silicene-like inner-edge systems Hang Xie(谢航), Xiao-Long Lü(吕小龙), and Jia-En Yang(杨加恩) 2024 (1):  18502-18502.  doi: 10.1088/1674-1056/ad0714 摘要 ( 177 )   HTML ( 4 )   PDF(5383KB) ( 136 )   Inner edge state with spin and valley degrees of freedom is a promising candidate for designing a dissipationless device due to the topological protection. The central challenge for the application of the inner edge state is to generate and modulate the polarized currents. In this work, we discover a new mechanism to generate fully valley- and spin—valley-polarized current caused by the Bloch wavevector mismatch (BWM). Based on this mechanism, we design some serial-typed inner-edge filters. By using once of the BWM, the coincident states could be divided into transmitted and reflected modes, which can serve as a valley or spin—valley filter. In particular, while with twice of the BWM, the incident current is absolutely reflected to support an off state with a specified valley and spin, which is different from the gap effect. These findings give rise to a new platform for designing valleytronics and spin-valleytronics. 参考文献 | 相关文章 | 计量指标

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Progress and realization platforms of dynamic topological photonics Qiu-Chen Yan(闫秋辰), Rui Ma(马睿), Xiao-Yong Hu(胡小永), and Qi-Huang Gong(龚旗煌) 2024 (1):  10301-10301.  doi: 10.1088/1674-1056/acf284 摘要 ( 168 )   HTML ( 8 )   PDF(4640KB) ( 177 )   Dynamic topological photonics is a novel research field, combining the time-domain optics and topological physics. In this review, the recent progress and realization platforms of dynamic topological photonics have been well introduced. The definition, measurement methods and the evolution process of the dynamic topological photonics are demonstrated to better understand the physical diagram. This review is meant to bring the readers a different perspective on topological photonics, grasp the advanced progress of dynamic topology, and inspire ideas about future prospects. 参考文献 | 相关文章 | 计量指标

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Capturing the non-equilibrium state in light—matter—free-electron interactions through ultrafast transmission electron microscopy Wentao Wang(汪文韬), Shuaishuai Sun(孙帅帅), Jun Li(李俊), Dingguo Zheng(郑丁国), Siyuan Huang(黄思远), Huanfang Tian(田焕芳), Huaixin Yang(杨槐馨), and Jianqi Li(李建奇) 2024 (1):  10701-10701.  doi: 10.1088/1674-1056/ad0141 摘要 ( 177 )   HTML ( 20 )   PDF(7082KB) ( 159 )   Ultrafast transmission electron microscope (UTEM) with the multimodality of time-resolved diffraction, imaging, and spectroscopy provides a unique platform to reveal the fundamental features associated with the interaction between free electrons and matter. In this review, we summarize the principles, instrumentation, and recent developments of the UTEM and its applications in capturing dynamic processes and non-equilibrium transient states. The combination of the transmission electron microscope with a femtosecond laser via the pump—probe method guarantees the high spatiotemporal resolution, allowing the investigation of the transient process in real, reciprocal and energy spaces. Ultrafast structural dynamics can be studied by diffraction and imaging methods, revealing the coherent acoustic phonon generation and photo-induced phase transition process. In the energy dimension, time-resolved electron energy-loss spectroscopy enables the examination of the intrinsic electronic dynamics of materials, while the photon-induced near-field electron microscopy extends the application of the UTEM to the imaging of optical near fields with high real-space resolution. It is noted that light—free-electron interactions have the ability to shape electron wave packets in both longitudinal and transverse directions, showing the potential application in the generation of attosecond electron pulses and vortex electron beams. 参考文献 | 相关文章 | 计量指标

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Attosecond ionization time delays in strong-field physics Yongzhe Ma(马永哲), Hongcheng Ni(倪宏程), and Jian Wu(吴健) 2024 (1):  13201-13201.  doi: 10.1088/1674-1056/ad0e5d 摘要 ( 239 )   HTML ( 70 )   PDF(1335KB) ( 272 )   Electronic processes within atoms and molecules reside on the timescale of attoseconds. Recent advances in the laser-based pump-probe interrogation techniques have made possible the temporal resolution of ultrafast electronic processes on the attosecond timescale, including photoionization and tunneling ionization. These interrogation techniques include the attosecond streak camera, the reconstruction of attosecond beating by interference of two-photon transitions, and the attoclock. While the former two are usually employed to study photoionization processes, the latter is typically used to investigate tunneling ionization. In this review, we briefly overview these timing techniques towards an attosecond temporal resolution of ionization processes in atoms and molecules under intense laser fields. In particular, we review the backpropagation method, which is a novel hybrid quantum-classical approach towards the full characterization of tunneling ionization dynamics. Continued advances in the interrogation techniques promise to pave the pathway towards the exploration of ever faster dynamical processes on an ever shorter timescale. 参考文献 | 相关文章 | 计量指标

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Photophysics of metal-organic frameworks: A brief overview Qingshuo Liu(刘晴硕), Junhong Yu(余俊宏), and Jianbo Hu(胡建波) 2024 (1):  17204-17204.  doi: 10.1088/1674-1056/acfe00 摘要 ( 151 )   HTML ( 72 )   PDF(1894KB) ( 126 )   Metal-organic frameworks (MOFs), which are self-assembled porous coordination materials, have garnered considerable attention in the fields of optoelectronics, photovoltaic, photochemistry, and photocatalysis due to their diverse structures and excellent tunability. However, the performance of MOF-based optoelectronic applications currently falls short of the industry benchmark. To enhance the performance of MOF materials, it is imperative to undertake comprehensive investigations aimed at gaining a deeper understanding of photophysics and sequentially optimizing properties related to photocarrier transport, recombination, interaction, and transfer. By utilizing femtosecond laser pulses to excite MOFs, time-resolved optical spectroscopy offers a means to observe and characterize these ultrafast microscopic processes. This approach adds the time coordinate as a novel dimension for comprehending the interaction between light and MOFs. Accordingly, this review provides a comprehensive overview of the recent advancements in the photophysics of MOFs and additionally outlines potential avenues for exploring the time domain in the investigation of MOFs. 参考文献 | 相关文章 | 计量指标

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Universal basis underlying temperature, pressure and size induced dynamical evolution in metallic glass-forming liquids H P Zhang(张华平), B B Fan(范蓓蓓), J Q Wu(吴佳琦), and M Z Li(李茂枝) 2024 (1):  16101-16101.  doi: 10.1088/1674-1056/acf994 摘要 ( 162 )   HTML ( 5 )   PDF(956KB) ( 97 )   The dramatic temperature-dependence of liquids dynamics has attracted considerable scientific interests and efforts in the past decades, but the physics of which remains elusive. In addition to temperature, some other parameters, such as pressure, loading and size, can also tune the liquid dynamics and induce glass transition, which makes the situation more complicated. Here, we performed molecular dynamics simulations for Ni50Zr50 bulk liquid and nanodroplet to study the dynamics evolution in the complex multivariate phase space, especially along the isotherm with the change of pressure or droplet size. It is found that the short-time Debye—Waller factor universally determines the long-time relaxation dynamics no matter how the temperature, pressure or size changes. The basic correlation even holds at the local atomic scale. This finding provides general understanding of the microscopic mechanism of dynamic arrest and dynamic heterogeneity. 参考文献 | 补充材料 | 相关文章 | 计量指标

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Anelasticity to plasticity transition in a model two-dimensional amorphous solid Baoshuang Shang(尚宝双) 2024 (1):  16102-16102.  doi: 10.1088/1674-1056/acf82c 摘要 ( 180 )   HTML ( 5 )   PDF(1637KB) ( 106 )   Anelasticity, as an intrinsic property of amorphous solids, plays a significant role in understanding their relaxation and deformation mechanism. However, due to the lack of long-range order in amorphous solids, the structural origin of anelasticity and its distinction from plasticity remain elusive. In this work, using frozen matrix method, we study the transition from anelasticity to plasticity in a two-dimensional model glass. Three distinct mechanical behaviors, namely, elasticity, anelasticity, and plasticity, are identified with control parameters in the amorphous solid. Through the study of finite size effects on these mechanical behaviors, it is revealed that anelasticity can be distinguished from plasticity. Anelasticity serves as an intrinsic bridge connecting the elasticity and plasticity of amorphous solids. Additionally, it is observed that anelastic events are localized, while plastic events are subextensive. The transition from anelasticity to plasticity is found to resemble the entanglement of long-range interactions between element excitations. This study sheds light on the fundamental nature of anelasticity as a key property of element excitations in amorphous solids. 参考文献 | 相关文章 | 计量指标

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Ultrafast dynamics in photo-excited Mott insulator Sr3Ir2O7 at high pressure Xia Yin(尹霞), Jianbo Zhang(张建波), Wang Dong(王东), Takeshi Nakagawa, Chunsheng Xia(夏春生), Caoshun Zhang(张曹顺), Weicheng Guo(郭伟程), Jun Chang(昌峻), and Yang Ding(丁阳) 2024 (1):  16103-16103.  doi: 10.1088/1674-1056/acdc8c 摘要 ( 144 )   HTML ( 4 )   PDF(1930KB) ( 111 )   High-pressure ultrafast dynamics, as a new crossed research direction, are sensitive to subtle non-equilibrium state changes that might be unresolved by equilibrium states measurements, providing crucial information for studying delicate phase transitions caused by complex interactions in Mott insulators. With time-resolved transient reflectivity measurements, we identified the new phases in the spin—orbit Mott insulator Sr3Ir2O7 at 300 K that was previously unidentified using conventional approaches such as x-ray diffraction. Significant pressure-dependent variation of the amplitude and lifetime obtained by fitting the reflectivity ΔR/R reveal the changes of electronic structure caused by lattice distortions, and reflect the critical phenomena of phase transitions. Our findings demonstrate the importance of ultrafast nonequilibrium dynamics under extreme conditions for understanding the phase transition of Mott insulators. 参考文献 | 相关文章 | 计量指标

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Ab initio nonadiabatic molecular dynamics study on spin—orbit coupling induced spin dynamics in ferromagnetic metals Wansong Zhu(朱万松), Zhenfa Zheng(郑镇法), Qijing Zheng(郑奇靖), and Jin Zhao(赵瑾) 2024 (1):  16301-16301.  doi: 10.1088/1674-1056/acf91d 摘要 ( 205 )   HTML ( 5 )   PDF(3703KB) ( 110 )   Understanding the photoexcitation induced spin dynamics in ferromagnetic metals is important for the design of photo-controlled ultrafast spintronic device. In this work, by the ab initio nonadiabatic molecular dynamics simulation, we have studied the spin dynamics induced by spin—orbit coupling (SOC) in Co and Fe using both spin-diabatic and spin-adiabatic representations. In Co system, it is found that the Fermi surface (EF) is predominantly contributed by the spin-minority states. The SOC induced spin flip will occur for the photo-excited spin-majority electrons as they relax to the EF, and the spin-minority electrons tend to relax to the EF with the same spin through the electron—phonon coupling (EPC). The reduction of spin-majority electrons and the increase of spin-minority electrons lead to demagnetization of Co within 100 fs. By contrast, in Fe system, the EF is dominated by the spin-majority states. In this case, the SOC induced spin flip occurs for the photo-excited spin-minority electrons, which leads to a magnetization enhancement. If we move the EF of Fe to higher energy by 0.6 eV, the EF will be contributed by the spin-minority states and the demagnetization will be observed again. This work provides a new perspective for understanding the SOC induced spin dynamics mechanism in magnetic metal systems. 参考文献 | 相关文章 | 计量指标

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Ultrafast carrier dynamics in GeSn thin film based on time-resolved terahertz spectroscopy Panpan Huang(黄盼盼), Youlu Zhang(张有禄), Kai Hu(胡凯), Jingbo Qi(齐静波), Dainan Zhang(张岱南), and Liang Cheng(程亮) 2024 (1):  17201-17201.  doi: 10.1088/1674-1056/accf7f 摘要 ( 151 )   HTML ( 9 )   PDF(977KB) ( 96 )   We measure the time-resolved terahertz spectroscopy of GeSn thin film and studied the ultrafast dynamics of its photo-generated carriers. The experimental results show that there are photo-generated carriers in GeSn under femtosecond laser excitation at 2500 nm, and its pump-induced photoconductivity can be explained by the Drude—Smith model. The carrier recombination process is mainly dominated by defect-assisted Auger processes and defect capture. The first- and second-order recombination rates are obtained by the rate equation fitting, which are (2.6±1.1)×10-2 ps-1 and (6.6±1.8)×10-19 cm3·ps-1, respectively. Meanwhile, we also obtain the diffusion length of photo-generated carriers in GeSn, which is about 0.4 μm, and it changes with the pump delay time. These results are important for the GeSn-based infrared optoelectronic devices, and demonstrate that GeSn materials can be applied to high-speed optoelectronic detectors and other applications. 参考文献 | 相关文章 | 计量指标

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Optical manipulation of the topological phase in ZrTe5 revealed by time- and angle-resolved photoemission Chaozhi Huang(黄超之), Chengyang Xu(徐骋洋), Fengfeng Zhu(朱锋锋), Shaofeng Duan(段绍峰), Jianzhe Liu(刘见喆), Lingxiao Gu(顾凌霄), Shichong Wang(王石崇), Haoran Liu(刘浩然), Dong Qian(钱冬), Weidong Luo(罗卫东), and Wentao Zhang(张文涛) 2024 (1):  17901-17901.  doi: 10.1088/1674-1056/ad0d9d 摘要 ( 166 )   HTML ( 5 )   PDF(1097KB) ( 115 )   High-resolution time- and angle-resolved photoemission measurements were conducted on the topological insulator ZrTe5. With strong femtosecond photoexcitation, a possible ultrafast phase transition from a weak to a strong topological insulating phase was experimentally realized by recovering the energy gap inversion in a time scale that was shorter than 0.15 ps. This photoinduced transient strong topological phase can last longer than 2 ps at the highest excitation fluence studied, and it cannot be attributed to the photoinduced heating of electrons or modification of the conduction band filling. Additionally, the measured unoccupied electronic states are consistent with the first-principles calculation based on experimental crystal lattice constants, which favor a strong topological insulating phase. These findings provide new insights into the longstanding controversy about the strong and weak topological properties in ZrTe5, and they suggest that many-body effects including electron—electron interactions must be taken into account to understand the equilibrium weak topological insulating phase in ZrTe5. 参考文献 | 补充材料 | 相关文章 | 计量指标

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Core-level spectroscopy of the photodissociation process of BrCN molecule Kun Zhou(周坤) and Han Wang(王涵) 2024 (1):  18702-18702.  doi: 10.1088/1674-1056/ad0cc9 摘要 ( 182 )   HTML ( 4 )   PDF(930KB) ( 119 )   Fewest-switches surfacing hopping (FSSH) simulations have been performed with the high-level multi-reference electronic structure method to explore the coupled electronic and nuclear dynamics upon photoexcitation of cyanogen bromide (BrCN). The potential energy surfaces (PES) of BrCN are charted as functions of the Jacobi coordinates (R, θ). An in-depth examination of the FSSH trajectories reveals the temporal dynamics of the molecule and the population changes of the lowest twelve states during BrCN's photodissociation process, which presents a rich tapestry of dynamical information. Furthermore, the carbon K-edge x-ray absorption spectroscopy (XAS) is calculated with multi-reference inner-shell spectral simulations. The rotation of the CN fragment and the elongation of the C—Br bond are found to be the reason for the peak shifting in the XAS. Our findings offer a nuanced interpretation for inner-shell probe investigations of BrCN, setting the stage for a deeper understanding of the photodissociation process of cyanogen halides molecules. 参考文献 | 补充材料 | 相关文章 | 计量指标

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A step to the decentralized real-time timekeeping network Fangmin Wang(王芳敏), Yufeng Chen(陈雨锋), Jianhua Zhou(周建华), Yuting Lin(蔺玉亭), Jun Yang(杨军), Bo Wang(王波), and Lijun Wang(王力军) 2024 (1):  10702-10702.  doi: 10.1088/1674-1056/acfa88 摘要 ( 193 )   HTML ( 1 )   PDF(1954KB) ( 128 )   The composite time scale (CTS) provides an accurate and stable time-frequency reference for modern science and technology. Conventional CTS always features a centralized network topology, which means that the CTS is accompanied by a local master clock. This largely restricts the stability and reliability of the CTS. We simulate the restriction and analyze the influence of the master clock on the CTS. It proves that the CTS's long-term stability is also positively related to that of the master clock, until the region dominated by the frequency drift of the H-maser (averaging time longer than ～105 s). Aiming at this restriction, a real-time clock network is utilized. Based on the network, a real-time CTS referenced by a stable remote master clock is achieved. The experiment comparing two real-time CTSs referenced by a local and a remote master clock respectively reveals that under open-loop steering, the stability of the CTS is improved by referencing to a remote and more stable master clock instead of a local and less stable master clock. In this way, with the help of the proposed scheme, the CTS can be referenced to the most stable master clock within the network in real time, no matter whether it is local or remote, making democratic polycentric timekeeping possible. 参考文献 | 相关文章 | 计量指标

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Design and simulation of an accelerometer based on NV center spin—strain coupling Lu-Min Ji(季鲁敏), Li-Ye Zhao(赵立业), and Yu-Hai Wang(王裕海) 2024 (1):  17301-17301.  doi: 10.1088/1674-1056/ad09ab 摘要 ( 206 )   HTML ( 1 )   PDF(1379KB) ( 120 )   The nitrogen-vacancy (NV) center quantum systems have emerged as versatile tools in the field of precision measurement because of their high sensitivity in spin state detection and miniaturization potential as solid-state platforms. In this paper, an acceleration sensing scheme based on NV spin—strain coupling is proposed, which can effectively eliminate the influence of the stray noise field introduced by traditional mechanical schemes. Through the finite element simulation, it is found that the measurement bandwidth of this ensemble NV spin system ranges from 3 kHz to hundreds of kHz with structure optimization. The required power is at the sub-μW level, corresponding to a noise-limited sensitivity of ${6.7\times }{{10}}^{{-5}}~{\rm g}/\sqrt {\rm Hz} $. Compared with other types of accelerometers, this micro-sized diamond sensor proposed here has low power consumption, exquisite sensitivity, and integration potential. This research opens a fresh perspective to realize an accelerometer with appealing comprehensive performance applied in biomechanics and inertial measurement fields. 参考文献 | 相关文章 | 计量指标

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Sharing quantum nonlocality in the noisy scenario Shu-Yuan Yang(杨舒媛), Jin-Chuan Hou(侯晋川), and Kan He(贺衎) 2024 (1):  10302-10302.  doi: 10.1088/1674-1056/ad062d 摘要 ( 263 )   HTML ( 5 )   PDF(1719KB) ( 291 )   It was showed in [Phys. Rev. Lett. 125 090401 (2020)] that there exist unbounded number of independent Bobs who can share quantum nonlocality with a single Alice by performing sequentially measurements on the Bob's half of the maximally entangled pure two-qubit state. However, from practical perspectives, errors in entanglement generation and noises in quantum measurements will result in the decay of nonlocality in the scenario. In this paper, we analyze the persistency and termination of sharing nonlocality in the noisy scenario. We first obtain the two sufficient conditions under which there exist n independent Bobs who can share nonlocality with a single Alice under noisy measurements and the noisy initial two qubit entangled state. Analyzing the two conditions, we find that the influences on persistency under different kinds of noises can cancel each other out. Furthermore, we describe the change patterns of the maximal nonlocality-sharing number under the influence of different noises. Finally, we extend our investigation to the case of arbitrary finite-dimensional systems. 参考文献 | 相关文章 | 计量指标

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Observation of flat-band localized state in a one-dimensional diamond momentum lattice of ultracold atoms Chao Zeng(曾超), Yue-Ran Shi(石悦然), Yi-Yi Mao(毛一屹), Fei-Fei Wu(武菲菲), Yan-Jun Xie(谢岩骏), Tao Yuan(苑涛), Han-Ning Dai(戴汉宁), and Yu-Ao Chen(陈宇翱) 2024 (1):  10303-10303.  doi: 10.1088/1674-1056/ad0cd1 摘要 ( 255 )   HTML ( 2 )   PDF(1406KB) ( 276 )   We investigated the one-dimensional diamond ladder in the momentum lattice platform. By inducing multiple two- and four-photon Bragg scatterings among specific momentum states, we achieved a flat band system based on the diamond model, precisely controlling the coupling strength and phase between individual lattice sites. Utilizing two lattice sites couplings, we generated a compact localized state associated with the flat band, which remained localized throughout the entire time evolution. We successfully realized the continuous shift of flat bands by adjusting the corresponding nearest neighbor hopping strength, enabling us to observe the complete localization process. This opens avenues for further exploration of more complex properties within flat-band systems, including investigating the robustness of flat-band localized states in disordered flat-band systems and exploring many-body localization in interacting flat-band systems. 参考文献 | 相关文章 | 计量指标

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Higher-order topological Anderson insulator on the Sierpiński lattice Huan Chen(陈焕), Zheng-Rong Liu(刘峥嵘), Rui Chen(陈锐), and Bin Zhou(周斌) 2024 (1):  17202-17202.  doi: 10.1088/1674-1056/ad09d4 摘要 ( 298 )   HTML ( 12 )   PDF(1459KB) ( 183 )   Disorder effects on topological materials in integer dimensions have been extensively explored in recent years. However, its influence on topological systems in fractional dimensions remains unclear. Here, we investigate the disorder effects on a fractal system constructed on the Sierpiński lattice in fractional dimensions. The system supports the second-order topological insulator phase characterized by a quantized quadrupole moment and the normal insulator phase. We find that the second-order topological insulator phase on the Sierpiński lattice is robust against weak disorder but suppressed by strong disorder. Most interestingly, we find that disorder can transform the normal insulator phase to the second-order topological insulator phase with an emergent quantized quadrupole moment. Finally, the disorder-induced phase is further confirmed by calculating the energy spectrum and the corresponding probability distributions. 参考文献 | 相关文章 | 计量指标

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Effects of carrier density and interactions on pairing symmetry in a t2g model Yun-Xiao Li(李云霄), Wen-Han Xi(西文翰), Zhao-Yang Dong(董召阳), Zi-Jian Yao(姚子健), Shun-Li Yu(于顺利), and Jian-Xin Li(李建新) 2024 (1):  17404-17404.  doi: 10.1088/1674-1056/ad1094 摘要 ( 253 )   HTML ( 10 )   PDF(4482KB) ( 283 )   By utilizing the fluctuation exchange approximation method, we perform a study on the superconducting pairing symmetry in a t2g three-orbital model on the square lattice. Although the tight-binding parameters of the model are based on Sr2RuO4, we have systematically studied the evolution of superconducting pairing symmetry with the carrier density and interactions, making our findings relevant to a broader range of material systems. Under a moderate Hund's coupling, we find that spin fluctuations dominate the superconducting pairing, leading to a prevalent spin-singlet pairing with a dx2-y2-wave symmetry for the carrier density within the range of n=1.5—4 per site. By reducing the Hund's coupling, the charge fluctuations are enhanced and play a crucial role in determining the pairing symmetry, leading to a transition of the pairing symmetry from the spin-singlet dx2-y2-wave to the spin-triplet p-wave. Furthermore, we find that the superconducting pairings are orbital dependent. As the carrier density changes from n=4 to n=1.5, the active orbitals for superconducting pairing shift from the quasi-two-dimensional orbital dxy to the quasi-one-dimensional orbitals dxz and dyz. 参考文献 | 相关文章 | 计量指标

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Optical study of magnetic topological insulator MnBi4Te7 Zhi-Yu Liao(廖知裕), Bing Shen(沈冰), Xiang-Gang Qiu(邱祥冈), and Bing Xu(许兵) 2024 (1):  17802-17802.  doi: 10.1088/1674-1056/ad08aa 摘要 ( 208 )   HTML ( 2 )   PDF(1149KB) ( 123 )   We present an infrared spectroscopy study of the magnetic topological insulator MnBi4Te7 with antiferromagnetic (AFM) order below the Néel temperature TN = 13 K. Our investigation reveals that the low-frequency optical conductivity consists of two Drude peaks, indicating a response of free carriers involving multiple bands. Interestingly, the narrow Drude peak grows strongly as the temperature decreases, while the broad Drude peak remains relatively unchanged. The onset of interband transitions starts around 2000 cm-1, followed by two prominent absorption peaks around 10000 cm-1 and 20000 cm-1. Upon cooling, there is a notable transfer of spectral weight from the interband transitions to the Drude response. Below TN, the AFM transition gives rise to small anomalies of the charge response due to a band reconstruction. These findings provide valuable insights into the interplay between magnetism and the electronic properties in MnBi4Te7. 参考文献 | 相关文章 | 计量指标

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Maskless fabrication of quasi-omnidirectional V-groove solar cells using an alkaline solution-based method Xingqian Chen(陈兴谦), Yan Wang(王燕), Wei Chen(陈伟), Yaoping Liu(刘尧平), Guoguang Xing(邢国光), Bowen Feng(冯博文), Haozhen Li(李昊臻), Zongheng Sun(孙纵横), and Xiaolong Du(杜小龙) 2024 (1):  18801-18801.  doi: 10.1088/1674-1056/ad0cd0 摘要 ( 187 )   HTML ( 2 )   PDF(1899KB) ( 101 )   Silicon passivated emitter and rear contact (PERC) solar cells with V-groove texture were fabricated using maskless alkaline solution etching with in-house developed additive. Compared with the traditional pyramid texture, the V-groove texture possesses superior effective minority carrier lifetime, enhanced p—n junction quality and better applied filling factor (FF). In addition, a V-groove texture can greatly reduce the shading area and edge damage of front Ag electrodes when the V-groove direction is parallel to the gridline electrodes. Due to these factors, the V-groove solar cells have a higher efficiency (21.78%) than pyramid solar cells (21.62%). Interestingly, external quantum efficiency (EQE) and reflectance of the V-groove solar cells exhibit a slight decrease when the incident light angle (θ) is increased from 0^o to 75^o, which confirms the excellent quasi omnidirectionality of the V-groove solar cells. The proposed V-groove solar cell design shows a 2.84% relative enhancement of energy output over traditional pyramid solar cells. 参考文献 | 补充材料 | 相关文章 | 计量指标

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Efficient method to calculate the eigenvalues of the Zakharov—Shabat system Shikun Cui(崔世坤) and Zhen Wang(王振) 2024 (1):  10201-10201.  doi: 10.1088/1674-1056/acd686 摘要 ( 148 )   HTML ( 0 )   PDF(739KB) ( 161 )   A numerical method is proposed to calculate the eigenvalues of the Zakharov—Shabat system based on Chebyshev polynomials. A mapping in the form of (ax) is constructed according to the asymptotic of the potential function for the Zakharov—Shabat eigenvalue problem. The mapping can distribute Chebyshev nodes very well considering the gradient for the potential function. Using Chebyshev polynomials, (ax) mapping, and Chebyshev nodes, the Zakharov—Shabat eigenvalue problem is transformed into a matrix eigenvalue problem. This method has good convergence for the Satsuma—Yajima potential and the convergence rate is faster than the Fourier collocation method. This method is not only suitable for simple potential functions but also converges quickly for a complex Y-shape potential. It can also be further extended to other linear eigenvalue problems. 参考文献 | 相关文章 | 计量指标

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A deep learning method based on prior knowledge with dual training for solving FPK equation Denghui Peng(彭登辉), Shenlong Wang(王神龙), and Yuanchen Huang(黄元辰) 2024 (1):  10202-10202.  doi: 10.1088/1674-1056/ad071b 摘要 ( 205 )   HTML ( 3 )   PDF(7755KB) ( 158 )   The evolution of the probability density function of a stochastic dynamical system over time can be described by a Fokker—Planck—Kolmogorov (FPK) equation, the solution of which determines the distribution of macroscopic variables in the stochastic dynamic system. Traditional methods for solving these equations often struggle with computational efficiency and scalability, particularly in high-dimensional contexts. To address these challenges, this paper proposes a novel deep learning method based on prior knowledge with dual training to solve the stationary FPK equations. Initially, the neural network is pre-trained through the prior knowledge obtained by Monte Carlo simulation (MCS). Subsequently, the second training phase incorporates the FPK differential operator into the loss function, while a supervisory term consisting of local maximum points is specifically included to mitigate the generation of zero solutions. This dual-training strategy not only expedites convergence but also enhances computational efficiency, making the method well-suited for high-dimensional systems. Numerical examples, including two different two-dimensional (2D), six-dimensional (6D), and eight-dimensional (8D) systems, are conducted to assess the efficacy of the proposed method. The results demonstrate robust performance in terms of both computational speed and accuracy for solving FPK equations in the first three systems. While the method is also applicable to high-dimensional systems, such as 8D, it should be noted that computational efficiency may be marginally compromised due to data volume constraints. 参考文献 | 相关文章 | 计量指标

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Research and application of composite stochastic resonance in enhancement detection Rui Gao(高蕊), Shangbin Jiao(焦尚彬), and Qiongjie Xue(薛琼婕) 2024 (1):  10203-10203.  doi: 10.1088/1674-1056/ad01a8 摘要 ( 137 )   HTML ( 0 )   PDF(4754KB) ( 79 )   Aiming at the problem that the intermediate potential part of the traditional bistable stochastic resonance model cannot be adjusted independently, a new composite stochastic resonance (NCSR) model is proposed by combining the Woods—Saxon (WS) model and the improved piecewise bistable model. The model retains the characteristics of the independent parameters of WS model and the improved piecewise model has no output saturation, all the parameters in the new model have no coupling characteristics. Under α stable noise environment, the new model is used to detect periodic signal and aperiodic signal, the detection results indicate that the new model has higher noise utilization and better detection effect. Finally, the new model is applied to image denoising, the results showed that under the same conditions, the output peak signal-to-noise ratio (PSNR) and the correlation number of NCSR method is higher than that of other commonly used linear denoising methods and improved piecewise SR methods, the effectiveness of the new model is verified. 参考文献 | 相关文章 | 计量指标

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Threshold-independent method for single-shot readout of spin qubits in semiconductor quantum dots Rui-Zi Hu(胡睿梓), Sheng-Kai Zhu(祝圣凯), Xin Zhang(张鑫), Yuan Zhou(周圆), Ming Ni(倪铭), Rong-Long Ma(马荣龙), Gang Luo(罗刚), Zhen-Zhen Kong(孔真真), Gui-Lei Wang(王桂磊), Gang Cao(曹刚), Hai-Ou Li(李海欧), and Guo-Ping Guo(郭国平) 2024 (1):  10304-10304.  doi: 10.1088/1674-1056/ace3a9 摘要 ( 181 )   HTML ( 0 )   PDF(1128KB) ( 108 )   The single-shot readout data process is essential for the realization of high-fidelity qubits and fault-tolerant quantum algorithms in semiconductor quantum dots. However, the fidelity and visibility of the readout process are sensitive to the choice of the thresholds and limited by the experimental hardware. By demonstrating the linear dependence between the measured spin state probabilities and readout visibilities along with dark counts, we describe an alternative threshold-independent method for the single-shot readout of spin qubits in semiconductor quantum dots. We can obtain the extrapolated spin state probabilities of the prepared probabilities of the excited spin state through the threshold-independent method. We then analyze the corresponding errors of the method, finding that errors of the extrapolated probabilities cannot be neglected with no constraints on the readout time and threshold voltage. Therefore, by limiting the readout time and threshold voltage, we ensure the accuracy of the extrapolated probability. We then prove that the efficiency and robustness of this method are 60 times larger than those of the most commonly used method. Moreover, we discuss the influence of the electron temperature on the effective area with a fixed external magnetic field and provide a preliminary demonstration for a single-shot readout of up to 0.7 K/1.5 T in the future. 参考文献 | 补充材料 | 相关文章 | 计量指标

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An underdamped and delayed tri-stable model-based stochastic resonance Yan-Fei Jin(靳艳飞), Hao-Tian Wang(王昊天), and Ting-Ting Zhang(张婷婷) 2024 (1):  10501-10501.  doi: 10.1088/1674-1056/ad01a6 摘要 ( 128 )   HTML ( 0 )   PDF(1520KB) ( 80 )   Stochastic resonance (SR) is investigated in an underdamped tri-stable potential system driven by Gaussian colored noise and a periodic excitation, where both displacement and velocity time-delayed states feedback are considered. It is challenging to study SR in a second-order delayed multi-stable system analytically. In this paper, the improved energy envelope stochastic average method is developed to derive the analytical expressions of stationary probability density (SPD) and spectral amplification. The effects of noise intensity, damping coefficient, and time delay on SR are analyzed. The results show that the shapes of joint SPD can be adjusted to the desired structure by choosing the time delay and feedback gains. For fixed time delay, the SR peak is increased for negative displacement or velocity feedback gain. Meanwhile, the SR peak is decreased while the optimal noise intensity increases with increasing correlation time of noise. The Monte Carlo simulations (MCS) confirm the effectiveness of the theoretical results. 参考文献 | 相关文章 | 计量指标

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Enhancing visual security: An image encryption scheme based on parallel compressive sensing and edge detection embedding Yiming Wang(王一铭), Shufeng Huang(黄树锋), Huang Chen(陈煌), Jian Yang(杨健), and Shuting Cai(蔡述庭) 2024 (1):  10502-10502.  doi: 10.1088/1674-1056/ad01a1 摘要 ( 165 )   HTML ( 0 )   PDF(8079KB) ( 51 )   A novel image encryption scheme based on parallel compressive sensing and edge detection embedding technology is proposed to improve visual security. Firstly, the plain image is sparsely represented using the discrete wavelet transform. Then, the coefficient matrix is scrambled and compressed to obtain a size-reduced image using the Fisher--Yates shuffle and parallel compressive sensing. Subsequently, to increase the security of the proposed algorithm, the compressed image is re-encrypted through permutation and diffusion to obtain a noise-like secret image. Finally, an adaptive embedding method based on edge detection for different carrier images is proposed to generate a visually meaningful cipher image. To improve the plaintext sensitivity of the algorithm, the counter mode is combined with the hash function to generate keys for chaotic systems. Additionally, an effective permutation method is designed to scramble the pixels of the compressed image in the re-encryption stage. The simulation results and analyses demonstrate that the proposed algorithm performs well in terms of visual security and decryption quality. 参考文献 | 相关文章 | 计量指标

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Characteristic analysis of 5D symmetric Hamiltonian conservative hyperchaotic system with hidden multiple stability Li-Lian Huang(黄丽莲), Yan-Hao Ma(马衍昊), and Chuang Li(李创) 2024 (1):  10503-10503.  doi: 10.1088/1674-1056/acf9e7 摘要 ( 166 )   HTML ( 0 )   PDF(6935KB) ( 80 )   Conservative chaotic systems have unique advantages over dissipative chaotic systems in the fields of secure communication and pseudo-random number generator because they do not have attractors but possess good traversal and pseudo-randomness. In this work, a novel five-dimensional (5D) Hamiltonian conservative hyperchaotic system is proposed based on the 5D Euler equation. The proposed system can have different types of coordinate transformations and time reversal symmetries. In this work, Hamilton energy and Casimir energy are analyzed firstly, and it is proved that the new system satisfies Hamilton energy conservation and can generate chaos. Then, the complex dynamic characteristics of the system are demonstrated and the conservatism and chaos characteristics of the system are verified through the correlation analysis methods such as phase diagram, equilibrium point, Lyapunov exponent, bifurcation diagram, and SE complexity. In addition, a detailed analysis of the multistable characteristics of the system reveals that many energy-related coexisting orbits exist. Based on the infinite number of center-type and saddle-type equilibrium points, the dynamic characteristics of the hidden multistability of the system are revealed. Then, the National Institute of Standards and Technology (NIST) test of the new system shows that the chaotic sequence generated by the system has strong pseudo-random. Finally, the circuit simulation and hardware circuit experiment of the system are carried out with Multisim simulation software and digital signal processor (DSP) respectively. The experimental results confirm that the new system has good ergodicity and realizability. 参考文献 | 相关文章 | 计量指标

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Static-to-kinematic modeling and experimental validation of tendon-driven quasi continuum manipulators with nonconstant subsegment stiffness Xian-Jie Zheng(郑先杰), Meng Ding(丁萌), Liao-Xue Liu(刘辽雪), Lu Wang(王璐), and Yu Guo(郭毓) 2024 (1):  10703-10703.  doi: 10.1088/1674-1056/acfaf8 摘要 ( 131 )   HTML ( 1 )   PDF(2071KB) ( 38 )   Continuum robots with high flexibility and compliance have the capability to operate in confined and cluttered environments. To enhance the load capacity while maintaining robot dexterity, we propose a novel non-constant subsegment stiffness structure for tendon-driven quasi continuum robots (TDQCRs) comprising rigid-flexible coupling subsegments. Aiming at real-time control applications, we present a novel static-to-kinematic modeling approach to gain a comprehensive understanding of the TDQCR model. The analytical subsegment-based kinematics for the multisection manipulator is derived based on screw theory and product of exponentials formula, and the static model considering gravity loading, actuation loading, and robot constitutive laws is established. Additionally, the effect of tension attenuation caused by routing channel friction is considered in the robot statics, resulting in improved model accuracy. The root-mean-square error between the outputs of the static model and the experimental system is less than 1.63% of the arm length (0.5 m). By employing the proposed static model, a mapping of bending angles between the configuration space and the subsegment space is established. Furthermore, motion control experiments are conducted on our TDQCR system, and the results demonstrate the effectiveness of the static-to-kinematic model. 参考文献 | 相关文章 | 计量指标

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Ab initio potential energy surface and anharmonic vibration spectrum of NF3+ Yan-Nan Chen(陈艳南), Jian-Gang Xu(徐建刚), Jiang-Peng Fan(范江鹏), Shuang-Xiong Ma(马双雄), Tian Guo(郭甜), and Yun-Guang Zhang(张云光) 2024 (1):  13101-13101.  doi: 10.1088/1674-1056/ad04c6 摘要 ( 113 )   HTML ( 1 )   PDF(1174KB) ( 35 )   Potential energy surfaces (PESs), vibrational frequencies, and infrared spectra are calculated for NF3+ using ab initio calculations, based on UCCSD(T)/cc-pVTZ combined with vibrational configuration interaction (VCI). Based on an iterative algorithm, the surfaces (SURF) program adds automatic points to the lattice representation of the potential function, the one-dimensional and two-dimensional PESs are calculated after reaching a convergence threshold, finally the smooth image of the potential energy surface is fitted. The PESs accurately account for the interaction between the different modes, with the mode q6 symmetrical stretching vibrations having the greatest effect on the potential energy change of the whole system throughout the potential energy surface shift. The anharmonic frequencies are obtained when the VCI matrix is diagonalized. Fundamental frequencies, overtones, and combination bands of NF3+ are calculated, which generate the degenerate phenomenon between their frequencies. Finally, the calculated anharmonic frequency is used to plot the infrared spectra. Modal antisymmetric stretching ν5 and symmetric stretching ν6 exhibit a phenomenon of large-intensity borrowing. This study can provide data to support the characterization in the laboratory. 参考文献 | 补充材料 | 相关文章 | 计量指标

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High-order harmonic generation of ZnO crystals in chirped and static electric fields Ling-Yu Zhang(张玲玉), Yong-Lin He(何永林), Zhuo-Xuan Xie(谢卓璇), Fang-Yan Gao(高芳艳), Qing-Yun Xu(徐清芸), Xin-Lei Ge(葛鑫磊), Xiang-Yi Luo(罗香怡), and Jing Guo(郭静) 2024 (1):  13102-13102.  doi: 10.1088/1674-1056/acfa89 摘要 ( 161 )   HTML ( 4 )   PDF(14461KB) ( 197 )   High harmonic generation in ZnO crystals under chirped single-color field and static electric field are investigated by solving the semiconductor Bloch equation (SBE). It is found that when the chirp pulse is introduced, the interference structure becomes obvious while the harmonic cutoff is not extended. Furthermore, the harmonic efficiency is improved when the static electric field is included. These phenomena are demonstrated by the classical recollision model in real space affected by the waveform of laser field and inversion symmetry. Specifically, the electron motion in k-space shows that the change of waveform and the destruction of the symmetry of the laser field lead to the incomplete X-structure of the crystal-momentum-resolved (k-resolved) inter-band harmonic spectrum. Furthermore, a pre-acceleration process in the solid four-step model is confirmed. 参考文献 | 相关文章 | 计量指标

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Collision off-axis position dependence of relativistic nonlinear Thomson inverse scattering of an excited electron in a tightly focused circular polarized laser pulse Yubo Wang(王禹博), Qingyu Yang(杨青屿), Yifan Chang(常一凡), Zongyi Lin(林宗熠), and Youwei Tian(田友伟) 2024 (1):  13301-13301.  doi: 10.1088/1674-1056/acd921 摘要 ( 142 )   HTML ( 1 )   PDF(5925KB) ( 41 )   This paper presents a novel view of the impact of electron collision off-axis positions on the dynamic properties and relativistic nonlinear Thomson inverse scattering of excited electrons within tightly focused, circularly polarized laser pulses of varying intensities. We examine the effects of the transverse ponderomotive force, specifically how the deviation angle and speed of electron motion are affected by the initial off-axis position of the electron and the peak amplitude of the laser pulse. When the laser pulse intensity is low, an increase in the electron's initial off-axis distance results in reduced spatial radiation power, improved collimation, super-continuum phenomena generation, red-shifting of the spectrum's harmonic peak, and significant symmetry in the radiation radial direction. However, in contradiction to conventional understandings, when the laser pulse intensity is relatively high, the properties of the relativistic nonlinear Thomson inverse scattering of the electron deviate from the central axis, changing direction in opposition to the aforementioned effects. After reaching a peak, these properties then shift again, aligning with the previous direction. The complex interplay of these effects suggests a greater nuance and intricacy in the relationship between laser pulse intensity, electron position, and scattering properties than previously thought. 参考文献 | 相关文章 | 计量指标

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Internal collision double ionization of molecules driven by co-rotating two-color circularly polarized laser pulses Xue-Feng Li(李雪峰), Yue Qiao(乔月), Dan Wu(吴丹), Rui-Xian Yu(蔚瑞贤), Ji-Gen Chen(陈基根), Jun Wang(王俊), Fu-Ming Guo(郭福明), and Yu-Jun Yang(杨玉军) 2024 (1):  13302-13302.  doi: 10.1088/1674-1056/acf5d8 摘要 ( 155 )   HTML ( 1 )   PDF(1316KB) ( 154 )   The double ionization process of molecules driven by co-rotating two-color circularly polarized fields is investigated with a three-dimensional classical ensemble model. Numerical results indicate that a considerable part of the sequential double ionization (DI) events of molecules occur through internal collision double ionization (ICD), and the ICD recollision mechanism is significantly different from that in non-sequential double ionization (NSDI). By analyzing the results of internuclear distances R=5 a.u. and 2 a.u., these two recollision mechanisms are studied in depth. It is found that the dynamic behaviors of the recollision mechanisms of NSDI and ICD are similar. For NSDI, the motion range of electrons after the ionization is relatively large, and the electrons will return to the core after a period of time. In the ICD process, electrons will rotate around the parent ion before ionization, and the distance of the electron motion is relatively small. After a period of time, the electrons will come back to the core and collide with another electron. Furthermore, the molecular internuclear distance has a significant effect on the electron dynamic behavior of the two ionization mechanisms. This study will help to understand the multi-electron ionization process of complex systems. 参考文献 | 相关文章 | 计量指标

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Electron vortices generation of photoelectron of H2+ by counter-rotating circularly polarized attosecond pulses Haojing Yang(杨浩婧), Xiaoyu Liu(刘晓煜), Fengzheng Zhu(朱风筝), Liguang Jiao(焦利光), and Aihua Liu(刘爱华) 2024 (1):  13303-13303.  doi: 10.1088/1674-1056/ad011a 摘要 ( 165 )   HTML ( 1 )   PDF(1733KB) ( 170 )   Molecular-frame photoelectron momentum distributions (MF-PMDs) of an H2+ molecule ion in the presence of a pair of counter-rotating circularly polarized attosecond extreme ultraviolet laser pulses is studied by numerically solving the two-dimensional time-dependent Schrödinger equation within the frozen-nuclei approximation. At small time delay, our simulations show that the electron vortex structure is sensitive to the time delay and relative phase between the counter-rotating pulses when they are partially overlapped. By adjusting time delay and relative phase, we have the ability to manipulate the MF-PMDs and the appearance of spiral arms. We further show that the internuclear distance can affect the spiral vortices due to its different transition cross sections in the parallel and perpendicular geometries. The lowest-order perturbation theory is employed to interpret these phenomena qualitatively. It is concluded that the internuclear distance-dependent transition cross sections and the confinement effect in diatomic molecules are responsible for the variation of vortex structures in the MF-PMDs. 参考文献 | 相关文章 | 计量指标

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Electric field and force characteristic of dust aerosol particles on the surface of high-voltage transmission line Yingge Liu(刘滢格), Xingcai Li(李兴财), Juan Wang(王娟), Xin Ma(马鑫), and Wenhai Sun(孙文海) 2024 (1):  14101-14101.  doi: 10.1088/1674-1056/ad0140 摘要 ( 148 )   HTML ( 8 )   PDF(9756KB) ( 141 )   High-voltage transmission lines play a crucial role in facilitating the utilization of renewable energy in regions prone to desertification. The accumulation of atmospheric particles on the surface of these lines can significantly impact corona discharge and wind-induced conductor displacement. Accurately quantifying the force exerted by particles adhering to conductor surfaces is essential for evaluating fouling conditions and making informed decisions. Therefore, this study investigates the changes in electric field intensity along branched conductors caused by various fouling layers and their resulting influence on the adhesion of dust particles. The findings indicate that as individual particle size increases, the field strength at the top of the particle gradually decreases and eventually stabilizes at approximately 49.22 kV/cm, which corresponds to a field strength approximately 1.96 times higher than that of an unpolluted transmission line. Furthermore, when particle spacing exceeds 15 times the particle size, the field strength around the transmission line gradually decreases and approaches the level observed on non-adhering surface. The electric field remains relatively stable. In a triangular arrangement of three particles, the maximum field strength at the tip of the fouling layer is approximately 1.44 times higher than that of double particles and 1.5 times higher compared to single particles. These results suggest that particles adhering to the transmission line have a greater affinity for adsorbing charged particles. Additionally, relevant numerical calculations demonstrate that in dry environments, the primary adhesion forces between particles and transmission lines follow an order of electrostatic force and van der Waals force. Specifically, at the minimum field strength, these forces are approximately 74.73 times and 19.43 times stronger than the gravitational force acting on the particles. 参考文献 | 相关文章 | 计量指标

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Intensity correlation properties of x-ray beams split with Laue diffraction Chang-Zhe Zhao(赵昌哲), Shang-Yu Si(司尚禹), Hai-Peng Zhang(张海鹏), Lian Xue(薛莲), Zhong-Liang Li(李中亮), and Ti-Qiao Xiao(肖体乔) 2024 (1):  14102-14102.  doi: 10.1088/1674-1056/acf206 摘要 ( 169 )   HTML ( 8 )   PDF(973KB) ( 46 )   Beam splitting is one of the main approaches to achieving x-ray ghost imaging, and the intensity correlation between diffraction beam and transmission beam will directly affect the imaging quality. In this paper, we investigate the intensity correlation between the split x-ray beams by Laue diffraction of stress-free crystal. The analysis based on the dynamical theory of x-ray diffraction indicates that the spatial resolution of diffraction image and transmission image are reduced due to the position shift of the exit beam. In the experimental setup, a stress-free crystal with a thickness of hundred-micrometers-level is used for beam splitting. The crystal is in a non-dispersive configuration equipped with a double-crystal monochromator to ensure that the dimension of the diffraction beam and transmission beam are consistent. A correlation coefficient of 0.92 is achieved experimentally and the high signal-to-noise ratio of the x-ray ghost imaging is anticipated. Results of this paper demonstrate that the developed beam splitter of Laue crystal has the potential in the efficient data acquisition of x-ray ghost imaging. 参考文献 | 相关文章 | 计量指标

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A 1-bit electronically reconfigurable beam steerable metasurface reflectarray with multiple polarization manipulations Yan Shi(史琰), Xi-Ya Xu(徐茜雅), Shao-Ze Wang(王少泽), Wen-Yue Wei(魏文岳), and Quan-Wei Wu(武全伟) 2024 (1):  14201-14201.  doi: 10.1088/1674-1056/acfa8a 摘要 ( 162 )   HTML ( 0 )   PDF(2450KB) ( 158 )   A 1-bit electronically controlled metasurface reflectarray is presented to achieve beam steering with multiple polarization manipulations. A metsurface unit cell loaded by two PIN diodes is designed. By switching the two PIN diodes between ON and OFF states, the isotropic and anisotropic reflections can be flexibly achieved. For either the isotropic reflection or the anisotropic reflection, the two operation states achieve the reflection coefficients with approximately equal magnitude and 180° out of phase, thus giving rise to the isotropic/anisotropic 1-bit metasurface unit cells. With the 1-bit unit cells, a 12-by-12 metasurface reflectarray is optimally designed and fabricated. Under either y- or x-polarized incident wave illumination, the reflectarray can achieve the co-polarized and cross-polarized beam scanning, respectively, with the peak gains of 20.08 dBi and 17.26 dBi within the scan range of about ±50°. With the right-handed circular polarization (RHCP) excitation, the left-handed circular polarization (LHCP) radiation with the peak gain of 16.98 dBic can be achieved within the scan range of ±50°. Good agreement between the experimental results and the simulation results are observed for 2D beam steering and polarization manipulation capabilities. 参考文献 | 相关文章 | 计量指标

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Young's double slit interference with vortex source Qilin Duan(段琦琳), Pengfei Zhao(赵鹏飞), Yuhang Yin(殷玉杭), and Huanyang Chen(陈焕阳) 2024 (1):  14202-14202.  doi: 10.1088/1674-1056/acfdfd 摘要 ( 164 )   HTML ( 0 )   PDF(1020KB) ( 156 )   The fast and convenient demultiplex of optical vortex (OV) mode is crucial for its further application. We propose a novel approach that combines classic Young's doublet with an OV source to effectively identify the OV mode through the analysis of interference patterns. The interference patterns of the OV source incident on the double slits can be perfectly illustrated by using both the classical double-slit interference method and the Huygens—Fresnel principle. The interference fringes will twist along the negative or positive direction of x axis when topological charge (TC) l>0 or l<0, and the degree of the movement varies with the TC, allowing for a quantitative display of the OV characteristics through the interference patterns. Additionally, we deduce analytically that the zeroth-order interference fringe has a linear relationship with the TC and the vertical position. These findings highlight the ability to identify the OV mode by analyzing the interference patterns produced by Young's doublet. 参考文献 | 相关文章 | 计量指标

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Phase sensitivity with a coherent beam and twin beams via intensity difference detection Jun Liu(刘俊), Tao Shao(邵涛), Chenlu Li(李晨露), Minyang Zhang(张敏洋), Youyou Hu(胡友友), Dongxu Chen(陈东旭), and Dong Wei(卫栋) 2024 (1):  14203-14203.  doi: 10.1088/1674-1056/ad0115 摘要 ( 147 )   HTML ( 1 )   PDF(818KB) ( 95 )   We focus on the Mach—Zehnder interferometer (MZI) with the input of a coherent beam and one of the bright entangled twin beams with an external power reference beam employed for measurement. The results show that the phase sensitivity can reach sub-Heisenberg limit and approach quantum Cramér—Rao bound by changing the squeezing parameters and the photon number of the coherent beam, under the phase-matching condition. The absence of the external power reference beam will degrade the performance of the phase sensitivity. Meanwhile, this scheme shows good robustness against the losses of the photon detectors. We present a detailed discussion about the phase sensitivities when the inputs are two coherent beams, or a coherent beam plus a single-mode squeezed vacuum beam based on the MZI. This scenario can be applied in the field of phase precision measurements and other optical sensors. 参考文献 | 相关文章 | 计量指标

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Bessel—Gaussian beam-based orbital angular momentum holography Jiaying Ji(季佳滢), Zhigang Zheng(郑志刚), Jialong Zhu(朱家龙), Le Wang(王乐), Xinguang Wang(王新光), and Shengmei Zhao(赵生妹) 2024 (1):  14204-14204.  doi: 10.1088/1674-1056/acfdff 摘要 ( 190 )   HTML ( 0 )   PDF(4843KB) ( 172 )   Orbital angular momentum (OAM), as a new degree of freedom, has recently been applied in holography technology. Due to the infinite helical mode index of OAM mode, a large number of holographic images can be reconstructed from an OAM-multiplexing hologram. However, the traditional design of an OAM hologram is constrained by the helical mode index of the selected OAM mode, for a larger helical mode index OAM mode has a bigger sampling distance, and the crosstalk is produced for different sampling distances for different OAM modes. In this paper, we present the design of the OAM hologram based on a Bessel—Gaussian beam, which is non-diffractive and has a self-healing property during its propagation. The Fourier transform of the Bessel—Gaussian beam is the perfect vortex mode that has the fixed ring radius for different OAM modes. The results of simulation and experiment have demonstrated the feasibility of the generation of the OAM hologram with the Bessel—Gaussian beam. The quality of the reconstructed holographic image is increased, and the security is enhanced. Additionally, the anti-interference property is improved owing to its self-healing property of the Bessel-OAM holography. 参考文献 | 相关文章 | 计量指标

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Finesse measurement for high-power optical enhancement cavity Xin-Yi Lu(陆心怡), Xing Liu(柳兴), Qi-Li Tian(田其立), Huan Wang(王焕), Jia-Jun Wang(汪嘉俊), and Li-Xin Yan(颜立新) 2024 (1):  14205-14205.  doi: 10.1088/1674-1056/acd8ad 摘要 ( 186 )   HTML ( 0 )   PDF(1176KB) ( 119 )   Finesse is a critical parameter for describing the characteristics of an optical enhancement cavity (OEC). This paper first presents a review of finesse measurement techniques, including a comparative analysis of the advantages, disadvantages, and potential limitations of several main methods from both theoretical and practical perspectives. A variant of the existing method called the free spectral range (FSR) modulation method is proposed and compared with three other finesse measurement methods, i.e., the fast-switching cavity ring-down (CRD) method, the rapidly swept-frequency (SF) CRD method, and the ringing effect method. A high-power OEC platform with a high finesse of approximately 16000 is built and measured with the four methods. The performance of these methods is compared, and the results show that the FSR modulation method and the fast-switching CRD method are more suitable and accurate than the other two methods for high-finesse OEC measurements. The CRD method and the ringing effect method can be implemented in open loop using simple equipment and are easy to perform. Additionally, recommendations for selecting finesse measurement methods under different conditions are proposed, which benefit the development of OEC and its applications. 参考文献 | 相关文章 | 计量指标

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Using harmonic beam combining to generate pulse-burst in nonlinear optical laser Yuan-Zhai Xu(许元斋), Zhen-Ling Li(李珍玲), Ao-Nan Zhang(张奥楠), Ke Liu(刘可), Jing-Jing Zhang(张晶晶), Xiao-Jun Wang(王小军), Qin-Jun Peng(彭钦军), and Zu-Yan Xu(许祖彦) 2024 (1):  14206-14206.  doi: 10.1088/1674-1056/ad011b 摘要 ( 139 )   HTML ( 0 )   PDF(2594KB) ( 20 )   The ultrashort lasers working in pulse-burst mode reveal great machining performance in recent years. The number of pulses in bursts effects greatly on the removal rate and roughness. To generate a more equal amplitude of pulses in burst with linear polarization output and time gap adjustable, we propose a new method by the harmonic beam combining (HBC). The beam combining is commonly used in adding pulses into the output beam while maintaining the pulse waveform and beam quality. In the HBC, dichroic mirrors are used to combine laser pulses of fundamental wave (FW) into harmonic wave (HW), and nonlinear crystals are used to convert the FW into HW. Therefore, HBC can add arbitrarily more HW pulses to generate pulse-burst in linear polarization with simple structure. The amplitude of each pulse in bursts can be adjusted the same to increase the stability of the burst, the time gap of each pulse can be adjusted precisely by proper time delay. Because HBC adds pulses sequentially, the peak power density of the burst is the same as each pulse, pulses can be combined without concern of back-conversion which often occurs in high peak power density. In the demonstration, the extendibility of HBC was verified by combining two beams with a third beam. The combined efficiency rates were larger than 99%, and the beam quality of each beam was maintained at M2 ≈ 1.4. 参考文献 | 相关文章 | 计量指标

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Giant and controllable Goos—Hänchen shift of a reflective beam off a hyperbolic metasurface of polar crystals Tian Xue(薛天), Yu-Bo Li(李宇博), Hao-Yuan Song(宋浩元), Xiang-Guang Wang(王相光), Qiang Zhang(张强), Shu-Fang Fu(付淑芳), Sheng Zhou(周胜), and Xuan-Zhang Wang(王选章) 2024 (1):  14207-14207.  doi: 10.1088/1674-1056/acdac2 摘要 ( 153 )   HTML ( 1 )   PDF(2466KB) ( 106 )   We conduct a theoretical analysis of the massive and tunable Goos—Hänchen (GH) shift on a polar crystal covered with periodical black phosphorus (BP)-patches in the THz range. The surface plasmon phonon polaritons (SPPPs), which are coupled by the surface phonon polaritons (SPhPs) and surface plasmon polaritons (SPPs), can greatly increase GH shifts. Based on the in-plane anisotropy of BP, two typical metasurface models are designed and investigated. An enormous GH shift of about -7565.58 λ0 is achieved by adjusting the physical parameters of the BP-patches. In the designed metasurface structure, the maximum sensitivity accompanying large GH shifts can reach about 6.43×108 λ0/RIU, which is extremely sensitive to the size, carrier density, and layer number of BP. Compared with a traditional surface plasmon resonance sensor, the sensitivity is increased by at least two orders of magnitude. We believe that investigating metasurface-based SPPPs sensors could lead to high-sensitivity biochemical detection applications. 参考文献 | 相关文章 | 计量指标

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Quasi-anti-parity—time-symmetric single-resonator micro-optical gyroscope with Kerr nonlinearity Jingtong Geng(耿靖童), Shuyi Xu(徐书逸), Ting Jin(靳婷), Shulin Ding(丁舒林), Liu Yang(杨柳), Ying Wang(王颖), and Yonggang Zhang(张勇刚) 2024 (1):  14208-14208.  doi: 10.1088/1674-1056/ad0773 摘要 ( 154 )   HTML ( 2 )   PDF(2554KB) ( 143 )   Parity—time (PT) and quasi-anti-parity—time (quasi-APT) symmetric optical gyroscopes have been proposed recently which enhance Sagnac frequency splitting. However, the operation of gyroscopes at the exceptional point (EP) is challenging due to strict fabrication requirements and experimental uncertainties. We propose a new quasi-APT-symmetric micro-optical gyroscope which can be operated at the EP by easily shifting the Kerr nonlinearity. A single resonator is used as the core sensitive component of the quasi-APT-symmetric optical gyroscope to reduce the size, overcome the strict structural requirements and detect small rotation rates. Moreover, the proposed scheme also has an easy readout method for the frequency splitting. As a result, the device achieves a frequency splitting 105 times higher than that of a classical resonant optical gyroscope with the Earth's rotation. This proposal paves the way for a new and valuable method for the engineering of micro-optical gyroscopes. 参考文献 | 相关文章 | 计量指标

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Performance analysis of single-focus phase singularity based on elliptical reflective annulus quadrangle-element coded spiral zone plates Huaping Zang(臧华平), Baozhen Wang(王宝珍), Chenglong Zheng(郑程龙), Lai Wei(魏来), Quanping Fan(范全平), Shaoyi Wang(王少义), Zuhua Yang(杨祖华), Weimin Zhou(周维民), Leifeng Cao(曹磊峰), and Haizhong Guo(郭海中) 2024 (1):  14209-14209.  doi: 10.1088/1674-1056/acde4f 摘要 ( 143 )   HTML ( 0 )   PDF(5450KB) ( 92 )   Optical vortices generated by the conventional vortex lens are usually disturbed by the undesired higher-order foci, which may lead to additional artifacts and thus degrade the contrast sensitivity. In this work, we propose an efficient methodology to combine the merit of elliptical reflective zone plates (ERZPs) and the advantage of spiral zone plates (SZPs) in establishing a specific single optical element, termed elliptical reflective annulus quadrangle-element coded spiral zone plates (ERAQSZPs) to generate single-focus phase singularity. Differing from the abrupt reflectance of the ERZPs, a series of randomly distributed nanometer apertures are adopted to realize the sinusoidal reflectance. Typically, according to our physical design, the ERAQSZPs are fabricated on a bulk substrate; therefore, the new idea can significantly reduce the difficulty in the fabrication process. Based on the Kirchhoff diffraction theory and convolution theorem, the focusing performance of ERAQSZPs is calculated. The results reveal that apart from the capability of generating optical vortices, ERAQSZPs can also integrate the function of focusing, energy selection, higher-order foci elimination, as well as high spectral resolution together. In addition, the focusing properties can be further improved by appropriately adjusting the parameters, such as zone number and the size of the consisted primitives. These findings are expected to direct a new direction toward improving the performance of optical capture, x-ray fluorescence spectra, and forbidden transition. 参考文献 | 相关文章 | 计量指标

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Effective transmittance of Fabry—Perot cavity under non-parallel beam incidence Yin-Sheng Lv(吕寅生), Pin-Hua Xie(谢品华), Jin Xu(徐晋), You-Tao Li(李友涛), and Hua-Rong Zhang(张华荣) 2024 (1):  14210-14210.  doi: 10.1088/1674-1056/ad0ec3 摘要 ( 171 )   HTML ( 2 )   PDF(3047KB) ( 92 )   The Fabry—Pérot (FP) resonant cavity is widely used in laser and spectroscopic measurements due to its unique interference transfer function (ITF). In the ideal case of parallel incident light, the ITF of the FP resonant cavity can be expressed by the Airy function. However, in reality, it is difficult to achieve perfect parallelism with collimated beams. In this article, a theoretical model is established for non-parallel light incidence, which assumes that the non-parallel incident light is a cone-shaped beam, and the cone angle is used to quantify the non-parallelism of the beam. The transmittance function of the FP resonant cavity under non-parallel light incidence is derived. The accuracy of the model is experimentally verified. Based on this model, the effects of divergence angle, tilt angle and FP cavity parameters (reflectivity, cavity length) on the ITF are studied. The reasons for the decrease in peak value, broadening and asymmetry of the interference peak under non-parallel light incidence are explained. It is suggested that a fine balance between the interference peak and the collimation effect of the incident light should be considered in the design and application of FP resonant cavities, especially for tilted applications such as angle-scanned spectroscopy. The research results of this article have certain significance for the design and application of FP resonant cavities. 参考文献 | 相关文章 | 计量指标

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Terahertz quasi-perfect vortex beam with integer-order and fractional-order generated by spiral spherical harmonic axicon Si-Yu Tu(涂思语), De-Feng Liu(刘德峰), Jin-Song Liu(刘劲松), Zhen-Gang Yang(杨振刚), and Ke-Jia Wang(王可嘉) 2024 (1):  14211-14211.  doi: 10.1088/1674-1056/acf91c 摘要 ( 147 )   HTML ( 0 )   PDF(13654KB) ( 121 )   We propose a new method to generate terahertz perfect vortex beam with integer-order and fractional-order. A new optical diffractive element composed of the phase combination of a spherical harmonic axicon and a spiral phase plate is designed and called spiral spherical harmonic axicon. A terahertz Gaussian beam passes through the spiral spherical harmonic axicon to generate a terahertz vortex beam. When only the topological charge number carried by spiral spherical harmonic axicon increases, the ring radius of terahertz vortex beam increases slightly, so the beam is shaped into a terahertz quasi-perfect vortex beam. Importantly, the terahertz quasi-perfect vortex beam can carry not only integer-order topological charge number but also fractional-order topological charge number. This is the first time that vortex beam and quasi-perfect vortex beam with fractional-order have been successfully realized in terahertz domain and experiment. 参考文献 | 相关文章 | 计量指标

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Effects of confining pressure and pore pressure on multipole borehole acoustic field in fluid-saturated porous media Zhi-Qiang Zhao(赵志强), Jin-Xia Liu(刘金霞), Jian-Yu Liu(刘建宇), and Zhi-Wen Cui(崔志文) 2024 (1):  14301-14301.  doi: 10.1088/1674-1056/acf9e6 摘要 ( 116 )   HTML ( 0 )   PDF(1087KB) ( 19 )   In-situ stress is a common stress in the exploration and development of oil reservoirs. Therefore, it is of great significance to study the propagation characteristics of borehole acoustic waves in fluid-saturated porous media under stress. Based on the acoustoelastic theory of fluid-saturated porous media, the field equation of fluid-saturated porous media under the conditions of confining pressure and pore pressure and the acoustic field formula of multipole source excitation in open hole are given. The influences of pore pressure and confining pressure on guided waves of multipole borehole acoustic field in fluid-saturated porous media are investigated. The numerical results show that the phase velocity and excitation intensity of guided wave increase significantly under the confining pressure. For a given confining pressure, the phase velocity of the guided wave decreases with pore pressure increasing. The excitation intensity of guided wave increases at low frequency and then decreases at high frequency with pore pressure increasing, except for that of Stoneley wave which decreases in the whole frequency range. These results will help us get an insight into the influences of confining pressure and pore pressure on the acoustic field of multipole source in borehole around fluid-saturated porous media. 参考文献 | 相关文章 | 计量指标

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Scheme of negative acoustic radiation force based on a multiple-layered spherical structure Menyang Gong(宫门阳), Xin Xu(徐鑫), Yupei Qiao(乔玉配), Jiehui Liu(刘杰惠), Aijun He(何爱军), and Xiaozhou Liu(刘晓宙) 2024 (1):  14302-14302.  doi: 10.1088/1674-1056/acfa80 摘要 ( 151 )   HTML ( 1 )   PDF(3735KB) ( 88 )   Acoustic radiation force (ARF), as an important particle manipulation method, has been extensively studied in recent years. With the introduction of the concept of "acoustic tweezers", negative acoustic radiation has become a research hotspot. In this paper, a scheme of realizing negative ARF based on the multiple-layered spherical structure design is proposed. The specific structure and design idea are presented. Detailed theoretical calculation analysis is carried out. Numerical simulations have been performed to verify the correctness of this prediction. The conjecture that the suppression of backscattering can achieve negative ARF is verified concretely, which greatly expands the application prospect and design ideas of the ARF. This work has laid a theoretical foundation for realizing precise control of the structure. 参考文献 | 相关文章 | 计量指标

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Discrete multi-step phase hologram for high frequency acoustic modulation Meng-Qing Zhou(周梦晴), Zhao-Xi Li(李照希), Yi Li(李怡), Ye-Cheng Wang(王业成), Juan Zhang(张娟), Dong-Dong Chen(谌东东), Yi Quan(全熠), Yin-Tang Yang(杨银堂), and Chun-Long Fei(费春龙) 2024 (1):  14303-14303.  doi: 10.1088/1674-1056/acf44c 摘要 ( 137 )   HTML ( 3 )   PDF(4622KB) ( 40 )   Acoustic holograms can recover wavefront stored acoustic field information and produce high-fidelity complex acoustic fields. Benefiting from the huge spatial information that traditional acoustic elements cannot match, acoustic holograms pursue the realization of high-resolution complex acoustic fields and gradually tend to high-frequency ultrasound applications. However, conventional continuous phase holograms are limited by three-dimensional (3D) printing size, and the presence of unavoidable small printing errors makes it difficult to achieve acoustic field reconstruction at high frequency accuracy. Here, we present an optimized discrete multi-step phase hologram. It can ensure the reconstruction quality of image with high robustness, and properly lower the requirement for the 3D printing accuracy. Meanwhile, the concept of reconstruction similarity is proposed to refine a measure of acoustic field quality. In addition, the realized complex acoustic field at 20 MHz promotes the application of acoustic holograms at high frequencies and provides a new way to generate high-fidelity acoustic fields. 参考文献 | 补充材料 | 相关文章 | 计量指标

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Electron characteristics and dynamics in sub-millimeter pulsed atmospheric dielectric barrier discharge Junlin Fang(方骏林), Yarong Zhang(张亚容), Chenzi Lu(卢陈梓), Lili Gu(顾莉莉), Shaofeng Xu(徐少锋), Ying Guo(郭颖), and Jianjun Shi(石建军) 2024 (1):  15201-15201.  doi: 10.1088/1674-1056/ad0118 摘要 ( 184 )   HTML ( 2 )   PDF(3106KB) ( 146 )   The discharge characteristics and mechanism of sub-millimeter pulsed dielectric barrier discharge in atmospheric-pressure helium are investigated experimentally and theoretically, demonstrating that when the discharge gap distance is reduced from 1.00 mm to 0.20 mm, the discharge ignition time is reduced to approximately 40 ns and discharge intensity is enhanced in terms of the discharge optical emission intensity and density of the plasma species, (energetic electrons with energy above 8.40 eV). The simulated results show that as the discharge gap distance is further reduced to 0.10 mm, the number of energetic electrons decreases, which is attributable to the contraction of plasma bulk regime and reduction of electron density in the discharge bulk. Conversely, the proportion of energetic electrons to the total electrons in the discharge monotonically increases as the discharge gap distance is reduced from 1.00 mm to 0.10 mm. It is proposed that a gap distance of 0.12 mm is optimal to achieve a high concentration and proportion of energetic electrons in sub-millimeter pulsed atmosphere dielectric barrier discharge. 参考文献 | 相关文章 | 计量指标

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Numerical study of alpha particle loss with toroidal field ripple based on CFETR steady-state scenario Niuqi Li(李钮琦), Yingfeng Xu(徐颖峰), Fangchuan Zhong(钟方川), and Debing Zhang(张德兵) 2024 (1):  15202-15202.  doi: 10.1088/1674-1056/ad03de 摘要 ( 151 )   HTML ( 0 )   PDF(3397KB) ( 74 )   Effects of plasma equilibrium parameters on the alpha particle loss with the toroidal field ripple based on the CFETR steady-state scenario have been numerically investigated by the orbit-following code GYCAVA. It is found that alpha particle losses decrease and loss regions become narrower with the plasma current increasing or with the magnetic field decreasing. It is because the ripple stochastic transport and the ripple well loss of alpha particle are reduced with the safety factor decreasing. Decrease of the plasma density and temperature can reduce alpha particle losses due to enhancement of the slowing-down effect. The direction of the toroidal magnetic field can significantly affect heat loads induced by lost alpha particle. The vertical asymmetry of heat loads induced by the clockwise and counter-clockwise toroidal magnetic fields are due to the fact that the ripple distribution is asymmetric about the mid-plane, which can be explained by the typical orbits of alpha particle. The maximal heat load of alpha particle for the clockwise toroidal magnetic field is much smaller than that for the counter-clockwise one. 参考文献 | 相关文章 | 计量指标

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Growth mechanism and characteristics of electron drift instability in Hall thruster with different propellant types Long Chen(陈龙), Zi-Chen Kan(阚子晨), Wei-Fu Gao(高维富), Ping Duan(段萍), Jun-Yu Chen(陈俊宇), Cong-Qi Tan(檀聪琦), and Zuo-Jun Cui(崔作君) 2024 (1):  15203-15203.  doi: 10.1088/1674-1056/acf9e5 摘要 ( 151 )   HTML ( 1 )   PDF(14453KB) ( 162 )   The existence of a significant electron drift instability (EDI) in the Hall thruster is considered as one of the possible causes of the abnormal increase in axial electron mobility near the outlet of the channel. In recent years, extensive simulation research on the characteristics of EDI has been conducted, but the excitation mechanism and growth mechanism of EDI in linear stage and nonlinear stage remain unclear. In this work, a one-dimensional PIC model in the azimuthal direction of the thruster near-exit region is established to gain further insights into the mechanism of the EDI in detail, and the effects of different types of propellants on EDI characteristics are discussed. The changes in axial electron transport caused by EDI under different types of propellants and electromagnetic field strengths are also examined. The results indicate that EDI undergoes a short linear growth phase before transitioning to the nonlinear phase and finally reaching saturation through the ion Landau damping. The EDI drives a significant ion heating in the azimuthal direction through electron--ion friction before entering the quasi-steady state, which increases the axial mobility of the electrons. Using lighter atomic weight propellant can effectively suppress the oscillation amplitude of EDI, but it will increase the linear growth rate, frequency, and phase velocity of EDI. Compared with the classical mobility, the axial electron mobility under the EDI increases by three orders of magnitude, which is consistent with experimental phenomena. The change of propellant type is insufficient to significantly change the axial electron mobility. It is also found that the collisions between electrons and neutral gasescan significantly affect the axial electron mobility under the influence of EDI, and lead the strength of the electric field to increase and the strength of the magnetic field to decrease, thereby both effectively suppressing the axial transport of electrons. 参考文献 | 相关文章 | 计量指标

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Fluid-chemical modeling of the near-cathode sheath formation process in a high current broken in DC air circuit breaker Shi-Dong Peng(彭世东), Jing Li(李静), Wei Duan(段薇), Yun-Dong Cao(曹云东), Shu-Xin Liu(刘树鑫), and Hao Huang(黄浩) 2024 (1):  15204-15204.  doi: 10.1088/1674-1056/acd7cb 摘要 ( 110 )   HTML ( 0 )   PDF(2971KB) ( 32 )   When the contacts of a medium-voltage DC air circuit breaker (DCCB) are separated, the energy distribution of the arc is determined by the formation process of the near-electrode sheath. Therefore, the voltage drop through the near-electrode sheath is an important means to build up the arc voltage, which directly determines the current-limiting performance of the DCCB. A numerical model to describe the near-electrode sheath formation process can provide insight into the physical mechanism of the arc formation, and thus provide a method for arc energy regulation. In this work, we establish a two-dimensional axisymmetric time-varying model of a medium-voltage DCCB arc when interrupted by high current based on a fluid-chemical model involving 16 kinds of species and 46 collision reactions. The transient distributions of electron number density, positive and negative ion number density, net space charge density, axial electric field, axial potential between electrodes, and near-cathode sheath are obtained from the numerical model. The computational results show that the electron density in the arc column increases, then decreases, and then stabilizes during the near-cathode sheath formation process, and the arc column's diameter gradually becomes wider. The 11.14 V—12.33 V drops along the 17 μm space charge layer away from the cathode (65.5 kV/m—72.5 kV/m) when the current varies from 20 kA—80 kA. The homogeneous external magnetic field has little effect on the distribution of particles in the near-cathode sheath core, but the electron number density at the near-cathode sheath periphery can increase as the magnetic field increases and the homogeneous external magnetic field will lead to arc diffusion. The validity of the numerical model can be proven by comparison with the experiment. 参考文献 | 相关文章 | 计量指标

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Transition from a filamentary mode to a diffuse one with varying distance from needle to stream of an argon plasma jet Hui-Min Xu(许慧敏), Jing-Ge Gao(高敬格), Peng-Ying Jia(贾鹏英), Jun-Xia Ran(冉俊霞), Jun-Yu Chen(陈俊宇), and Jin-Mao Li(李金懋) 2024 (1):  15205-15205.  doi: 10.1088/1674-1056/ad0149 摘要 ( 140 )   HTML ( 1 )   PDF(3465KB) ( 46 )   Plasma jet has extensive application potentials in various fields, which normally operates in a diffuse mode when helium is used as the working gas. However, when less expensive argon is used, the plasma jet often operates in a filamentary mode. Compared to the filamentary mode, the diffuse mode is more desirable for applications. Hence, many efforts have been exerted to accomplish the diffuse mode of the argon plasma jet. In this paper, a novel single-needle argon plasma jet is developed to obtain the diffuse mode. It is found that the plasma jet operates in the filamentary mode when the distance from the needle tip to the central line of the argon stream (d) is short. It transits to the diffuse mode with increasing d. For the diffuse mode, there is always one discharge pulse per voltage cycle, which initiates at the rising edge of the positive voltage. For comparison, the number of discharge pulse increases with an increase in the peak voltage for the filamentary mode. Fast photography reveals that the plasma plume in the filamentary mode results from a guided positive streamer, which propagates in the argon stream. However, the plume in the diffuse mode originates from a branched streamer, which propagates in the interfacial layer between the argon stream and the surrounding air. By optical emission spectroscopy, plasma parameters are investigated for the two discharge modes, which show a similar trend with increasing d. The diffuse mode has lower electron temperature, electron density, vibrational temperature, and gas temperature compared to the filamentary mode. 参考文献 | 相关文章 | 计量指标

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Suppression of stimulated Brillouin and Raman scatterings using an alternating frequency laser and transverse magnetic fields Rui-Jin Cheng(程瑞锦), Xiao-Xun Li(李晓旬), Qing Wang(王清), De-Ji Liu(刘德基), Zhuo-Ming Huang(黄卓明), Shuai-Yu Lv(吕帅宇), Yuan-Zhi Zhou(周远志), Shu-Tong Zhang(张舒童), Xue-Ming Li(李雪铭), Zu-Jie Chen(陈祖杰), Qiang Wang(王强), Zhan-Jun Liu(刘占军), Li-Hua Cao(曹莉华), and Chun-Yang Zheng(郑春阳) 2024 (1):  15206-15206.  doi: 10.1088/1674-1056/ad0716 摘要 ( 162 )   HTML ( 0 )   PDF(2025KB) ( 146 )   A novel scheme to suppress both stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS) by combining an alternating frequency (AF) laser and a transverse magnetic field is proposed. The AF laser allows the laser frequency to change discretely and alternately over time. The suppression of SBS is significant as long as the AF difference is greater than the linear growth rate of SBS or the alternating time of the laser frequency is shorter than the linear growth time of SBS. However, the AF laser proves ineffective in suppressing SRS, which usually has a much higher linear growth rate than SBS. To remedy that, a transverse magnetic field is included to suppress the SRS instability. The electrons trapped in the electron plasma waves (EPWs) of SRS can be accelerated by the surfatron mechanism in a transverse magnetic field and eventually detrapped. While continuously extracting energy from EPWs, the EPWs are dissipated and the kinetic inflation of SRS is suppressed. The one-dimensional particle-in-cell simulation results show that both SBS and SRS can be effectively suppressed by combining the AF laser with a transverse magnetic field with tens of Tesla. The total reflectivity can be dramatically reduced by more than one order of magnitude. These results provide a potential reference for controlling SBS and SRS under the related parameters of inertial confinement fusion. 参考文献 | 相关文章 | 计量指标

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Sensitivity investigation of 100-MeV proton irradiation to SiGe HBT single event effect Ya-Hui Feng(冯亚辉), Hong-Xia Guo(郭红霞), Yi-Wei Liu(刘益维), Xiao-Ping Ouyang(欧阳晓平), Jin-Xin Zhang(张晋新), Wu-Ying Ma(马武英), Feng-Qi Zhang(张凤祁), Ru-Xue Bai(白如雪), Xiao-Hua Ma(马晓华), and Yue Hao(郝跃) 2024 (1):  16104-16104.  doi: 10.1088/1674-1056/acf303 摘要 ( 149 )   HTML ( 0 )   PDF(2002KB) ( 35 )   The single event effect (SEE) sensitivity of silicon—germanium heterojunction bipolar transistor (SiGe HBT) irradiated by 100-MeV proton is investigated. The simulation results indicate that the most sensitive position of the SiGe HBT device is the emitter center, where the protons pass through the larger collector-substrate (CS) junction. Furthermore, in this work the experimental studies are also carried out by using 100-MeV proton. In order to consider the influence of temperature on SEE, both simulation and experiment are conducted at a temperature of 93 K. At a cryogenic temperature, the carrier mobility increases, which leads to higher transient current peaks, but the duration of the current decreases significantly. Notably, at the same proton flux, there is only one single event transient (SET) that occurs at 93 K. Thus, the radiation hard ability of the device increases at cryogenic temperatures. The simulation results are found to be qualitatively consistent with the experimental results of 100-MeV protons. To further evaluate the tolerance of the device, the influence of proton on SiGe HBT after gamma-ray (60Coγ) irradiation is investigated. As a result, as the cumulative dose increases, the introduction of traps results in a significant reduction in both the peak value and duration of the transient currents. 参考文献 | 相关文章 | 计量指标

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Effect of grain size on gas bubble evolution in nuclear fuel: Phase-field investigations Dan Sun(孙丹), Qingfeng Yang(杨青峰), Jiajun Zhao(赵家珺), Shixin Gao(高士鑫), Yong Xin(辛勇), Yi Zhou(周毅), Chunyu Yin(尹春雨), Ping Chen(陈平), Jijun Zhao(赵纪军), and Yuanyuan Wang(王园园) 2024 (1):  16105-16105.  doi: 10.1088/1674-1056/ad08a6 摘要 ( 147 )   HTML ( 0 )   PDF(5537KB) ( 94 )   Numerous irradiation-induced gas bubbles are created in the nuclear fuel during irradiation, leading to the change of microstructure and the degradation of mechanical and thermal properties. The grain size of fuel is one of the important factors affecting bubble evolution. In current study, we first predict the thermodynamic behaviors of point defects as well as the interplay between vacancy and gas atom in both UO2 and U3Si2 according to ab initio approach. Then, we establish the irradiation-induced bubble phase-field model to investigate the formation and evolution of intra- and inter-granular gas bubbles. The effects of fission rate and temperature on the evolutions of bubble morphologies in UO2 and U3Si2 have been revealed. Especially, a comparison of porosities under different grain sizes is examined and analyzed. To understand the thermal conductivity as functions of grain size and porosity, the heat transfer capability of U3Si2 is evaluated. 参考文献 | 相关文章 | 计量指标

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Simulation of space heavy-ion induced primary knock-on atoms in bipolar devices Bin Zhang(张彬), Hao Jiang(姜昊), Xiao-Dong Xu(徐晓东), Tao Ying(应涛), Zhong-Li Liu(刘中利), Wei-Qi Li(李伟奇), Jian-Qun Yang(杨剑群), and Xing-Ji Li(李兴冀) 2024 (1):  16106-16106.  doi: 10.1088/1674-1056/acd3e1 摘要 ( 154 )   HTML ( 0 )   PDF(7552KB) ( 52 )   Bipolar junction transistors (BJTs) are often used in spacecraft due to their excellent working characteristics. However, the complex space radiation environment induces primary knock-on atoms (PKAs) in BJTs through collisions, resulting in hard-to-recover displacement damage and affecting the performance of electronic components. In this paper, the properties of PKAs induced by typical space heavy ions (C, N, O, Fe) in BJTs are investigated using Monte Carlo simulations. The simulated results show that the energy spectrum of ion-induced PKAs is primarily concentrated in the low-energy range (17 eV—100 eV) and displays similar features across all tested ions. The PKAs induced by the collision of energetic ions have large forward scattering angles, mainly around 88°. Moreover, the distribution of PKAs within a transistor as a function of depth displays a peak characteristic, and the peak position is linearly proportional to the incident energy at a certain energy range. These simulation outcomes serve as crucial theoretical support for long-term semiconductor material defect evolution and ground testing of semiconductor devices. 参考文献 | 相关文章 | 计量指标

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Hamiltonian system for the inhomogeneous plane elasticity of dodecagonal quasicrystal plates and its analytical solutions Zhiqiang Sun(孙志强), Guolin Hou(侯国林), Yanfen Qiao(乔艳芬), and Jincun Liu (刘金存) 2024 (1):  16107-16107.  doi: 10.1088/1674-1056/acfaf3 摘要 ( 160 )   HTML ( 2 )   PDF(706KB) ( 37 )   A Hamiltonian system is derived for the plane elasticity problem of two-dimensional dodecagonal quasicrystals by introducing the simple state function. By using symplectic elasticity approach, the analytic solutions of the phonon and phason displacements are obtained further for the quasicrystal plates. In addition, the effectiveness of the approach is verified by comparison with the data of the finite integral transformation method. 参考文献 | 相关文章 | 计量指标

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Linear magnetoresistance and structural distortion in layered SrCu4-xP2 single crystals Yong Nie(聂勇), Zheng Chen(陈正), Wensen Wei(韦文森), Huijie Li(李慧杰), Yong Zhang(张勇), Ming Mei(梅明), Yuanyuan Wang(王园园), Wenhai Song(宋文海), Dongsheng Song(宋东升), Zhaosheng Wang(王钊胜), Xiangde Zhu(朱相德), Wei Ning(宁伟), and Mingliang Tian(田明亮) 2024 (1):  16108-16108.  doi: 10.1088/1674-1056/acf705 摘要 ( 139 )   HTML ( 0 )   PDF(1255KB) ( 185 )   We report a systematic study on layered metal SrCu4-xP2 single crystals via transport, magnetization, thermodynamic measurements and structural characterization. We find that the crystals show large linear magnetoresistance without any sign of saturation with a magnetic field up to 30 T. We also observe a phase transition with significant anomalies in resistivity and heat capacity at Tp ～ 140 K. Thermal expansion measurement reveals a subtle lattice parameter variation near Tp, i.e., ΔLc/Lc～ 0.062%. The structural characterization confines that there is no structure transition below and above Tp. All these results suggest that the nonmagnetic transition of SrCu4-xP2 could be associated with structural distortion. 参考文献 | 相关文章 | 计量指标

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Geometries and electronic structures of ZrnCu(n =2-12) clusters: A joint machine-learning potential density functional theory investigation Yizhi Wang(王一志), Xiuhua Cui(崔秀花), Jing Liu(刘静), Qun Jing(井群), Haiming Duan(段海明), and Haibin Cao(曹海宾) 2024 (1):  16109-16109.  doi: 10.1088/1674-1056/acd5c2 摘要 ( 146 )   HTML ( 1 )   PDF(3828KB) ( 38 )   Zr-based amorphous alloys have attracted extensive attention because of their large glassy formation ability, wide supercooled liquid region, high elasticity, and unique mechanical strength induced by their icosahedral local structures. To determine the microstructures of Zr—Cu clusters, the stable and metastable geometry of ZrnCu (n=2—12) clusters are screened out via the CALYPSO method using machine-learning potentials, and then the electronic structures are investigated using density functional theory. The results show that the ZrnCu (n≥ 3) clusters possess three-dimensional geometries, ZrnCu (n≥ 9) possess cage-like geometries, and the Zr12Cu cluster has icosahedral geometry. The binding energy per atom gradually gets enlarged with the increase in the size of the clusters, and ZrnCu (n=5, 7, 9, 12) have relatively better stability than their neighbors. The magnetic moment of most ZrnCu clusters is just 1μB, and the main components of the highest occupied molecular orbitals (HOMOs) in the Zr12Cu cluster come from the Zr-d state. There are hardly any localized two-center bonds, and there are about 20 σ-type delocalized three-center bonds. 参考文献 | 补充材料 | 相关文章 | 计量指标

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Temperature effect on nanotwinned Ni under nanoindentation using molecular dynamic simulation Xi He(何茜), Ziyi Xu(徐子翼), and Yushan Ni(倪玉山) 2024 (1):  16201-16201.  doi: 10.1088/1674-1056/acf997 摘要 ( 137 )   HTML ( 0 )   PDF(5638KB) ( 39 )   Temperature effect on atomic deformation of nanotwinned Ni (nt-Ni) under localized nanoindentation is investigated in comparison with nanocrystalline Ni (nc-Ni) through molecular simulation. The nt-Ni exhibits enhanced critical load and hardness compared to nc-Ni, where perfect, stair-rod and Shockley dislocations are activated at $(1\bar{1}1)$, $(\bar{1}11)$ and $(11\bar{1})$ slip planes in nt-Ni compared to only Shockley dislocation nucleation at $(1\bar{1}1)$ and $(\bar{1}11)$ slip planes of nc-Ni. The nt-Ni exhibits a less significant indentation size effect in comparison with nc-Ni due to the dislocation slips hindrance of the twin boundary. The atomic deformation associated with the indentation size effect is investigated during dislocation transmission. Different from the decreasing partial slips parallel to the indenter surface in nc-Ni with increasing temperature, the temperature-dependent atomic deformation of nt-Ni is closely related to the twin boundary: from the partial slips parallel to the twin boundary (~10 K), to increased confined layer slips and decreased twin migration(300 K—600 K), to decreased confined layer slips and increased dislocation interaction of dislocation pinning and dissociation (900 K—1200 K). Dislocation density and atomic structure types through quantitative analysis are implemented to further reveal the above-mentioned dislocation motion and atomic structure alteration. Our study is helpful for understanding the temperature-dependent plasticity of twin boundary in nanotwinned materials. 参考文献 | 相关文章 | 计量指标

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Atomistic evaluation of tension—compression asymmetry in nanoscale body-centered-cubic AlCrFeCoNi high-entropy alloy Runlong Xing(邢润龙) and Xuepeng Liu(刘雪鹏) 2024 (1):  16202-16202.  doi: 10.1088/1674-1056/acfc37 摘要 ( 127 )   HTML ( 0 )   PDF(7171KB) ( 94 )   The tension and compression of face-centered-cubic high-entropy alloy (HEA) nanowires are significantly asymmetric, but the tension--compression asymmetry in nanoscale body-centered-cubic (BCC) HEAs is still unclear. In this study, the tension--compression asymmetry of the BCC AlCrFeCoNi HEA nanowire is investigated using molecular dynamics simulations. The results show a significant asymmetry in both the yield and flow stresses, with BCC HEA nanowire stronger under compression than under tension. The strength asymmetry originates from the completely different deformation mechanisms in tension and compression. In compression, atomic amorphization dominates plastic deformation and contributes to the strengthening, while in tension, deformation twinning prevails and weakens the HEA nanowire. The tension--compression asymmetry exhibits a clear trend of increasing with the increasing nanowire cross-sectional edge length and decreasing temperature. In particular, the compressive strengths along the [001] and [111] crystallographic orientations are stronger than the tensile counterparts, while the [110] crystallographic orientation shows the exactly opposite trend. The dependences of tension--compression asymmetry on the cross-sectional edge length, crystallographic orientation, and temperature are explained in terms of the deformation behavior of HEA nanowire as well as its variations caused by the change in these influential factors. These findings may deepen our understanding of the tension--compression asymmetry of the BCC HEA nanowires. 参考文献 | 相关文章 | 计量指标

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Determining Hubbard U of VO2 by the quasi-harmonic approximation Longjuan Kong(孔龙娟), Yuhang Lu(陆雨航), Xinying Zhuang(庄新莹), Zhiyong Zhou(周志勇), and Zhenpeng Hu(胡振芃) 2024 (1):  16302-16302.  doi: 10.1088/1674-1056/acfd18 摘要 ( 155 )   HTML ( 0 )   PDF(1284KB) ( 51 )   Vanadium dioxide VO2 is a strongly correlated material that undergoes a metal-to-insulator transition around 340 K. In order to describe the electron correlation effects in VO2, the DFT + U method is commonly employed in calculations. However, the choice of the Hubbard U parameter has been a subject of debate and its value has been reported over a wide range. In this paper, taking focus on the phase transition behavior of VO2, the Hubbard U parameter for vanadium oxide is determined by using the quasi-harmonic approximation (QHA). First-principles calculations demonstrate that the phase transition temperature can be modulated by varying the U values. The phase transition temperature can be well reproduced by the calculations using the Perdew—Burke—Ernzerhof functional combined with the U parameter of 1.5 eV. Additionally, the calculated band structure, insulating or metallic properties, and phonon dispersion with this U value are in line with experimental observations. By employing the QHA to determine the Hubbard U parameter, this study provides valuable insights into the phase transition behavior of VO2. The findings highlight the importance of electron correlation effects in accurately describing the properties of this material. The agreement between the calculated results and experimental observations further validates the chosen U value and supports the use of the DFT+U method in studying VO2. 参考文献 | 相关文章 | 计量指标

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Effects of Mg-doping temperature on the structural and electrical properties of nonpolar a-plane p-type GaN films Kai Chen(陈凯), Jianguo Zhao(赵见国), Yu Ding(丁宇), Wenxiao Hu(胡文晓), Bin Liu(刘斌), Tao Tao(陶涛), Zhe Zhuang(庄喆), Yu Yan(严羽), Zili Xie(谢自力), Jianhua Chang(常建华), Rong Zhang(张荣), and Youliao Zheng(郑有炓) 2024 (1):  16801-16801.  doi: 10.1088/1674-1056/acdc0b 摘要 ( 150 )   HTML ( 0 )   PDF(872KB) ( 81 )   Nonpolar (11—20) a-plane p-type GaN films were successfully grown on r-plane sapphire substrate with the metal—organic chemical vapor deposition (MOCVD) system. The effects of Mg-doping temperature on the structural and electrical properties of nonpolar p-type GaN films were investigated in detail. It is found that all the surface morphology, crystalline quality, strains, and electrical properties of nonpolar a-plane p-type GaN films are interconnected, and are closely related to the Mg-doping temperature. This means that a proper performance of nonpolar p-type GaN can be expected by optimizing the Mg-doping temperature. In fact, a hole concentration of 1.3×1018 cm-3, a high Mg activation efficiency of 6.5%, an activation energy of 114 meV for Mg acceptor, and a low anisotropy of 8.3% in crystalline quality were achieved with a growth temperature of 990 ℃. This approach to optimizing the Mg-doping temperature of the nonpolar a-plane p-type GaN film provides an effective way to fabricate high-efficiency optoelectronic devices in the future. 参考文献 | 相关文章 | 计量指标

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Majorana noise model and its influence on the power spectrum Shumeng Chen(陈书梦), Sifan Ding(丁思凡), Zhen-Tao Zhang(张振涛), and Dong E. Liu(刘东) 2024 (1):  17101-17101.  doi: 10.1088/1674-1056/acfd19 摘要 ( 152 )   HTML ( 0 )   PDF(2745KB) ( 113 )   Majorana quantum computation offers a potential approach to securely manipulating and storing quantum data in a topological manner that may effectively resist the decoherence induced by local noise. However, actual Majorana qubit setups are susceptible to noise. In this study, from a quantum dynamics perspective, we develop a noise model for Majorana qubits that accounts for quasi-particle poisoning and Majorana overlapping with fluctuation. Furthermore, we focus on Majorana parity readout methodologies, specifically those leveraging an ancillary quantum dot, and carry out an in-depth exploration of continuous measurement techniques founded on the quantum jump model of a quantum point contact. Utilizing these methodologies, we proceed to analyze the influence of noise on the afore-mentioned noise model, employing numerical computation to evaluate the power spectrum and frequency curve. In the culmination of our study, we put forward a strategy to benchmark the presence and detailed properties of noise in Majorana qubits. 参考文献 | 相关文章 | 计量指标

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Quantitative determination of the critical points of Mott metal—insulator transition in strongly correlated systems Yuekun Niu(牛月坤), Yu Ni(倪煜), Jianli Wang(王建利), Leiming Chen(陈雷鸣), Ye Xing(邢晔), Yun Song(宋筠), and Shiping Feng(冯世平) 2024 (1):  17102-17102.  doi: 10.1088/1674-1056/ad0719 摘要 ( 142 )   HTML ( 0 )   PDF(638KB) ( 103 )   Mottness is at the heart of the essential physics in a strongly correlated system as many novel quantum phenomena occur in the metallic phase near the Mott metal—insulator transition. We investigate the Mott transition in a Hubbard model by using the dynamical mean-field theory and introduce the local quantum state fidelity to depict the Mott metal—insulator transition. The local quantum state fidelity provides a convenient approach to determining the critical point of the Mott transition. Additionally, it presents a consistent description of the two distinct forms of the Mott transition points. 参考文献 | 相关文章 | 计量指标

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Physical mechanism of oxygen diffusion in the formation of Ga2O3 Ohmic contacts Su-Yu Xu(徐宿雨), Miao Yu(于淼), Dong-Yang Yuan(袁东阳), Bo Peng(彭博), Lei Yuan(元磊), Yu-Ming Zhang(张玉明), and Ren-Xu Jia(贾仁需) 2024 (1):  17302-17302.  doi: 10.1088/1674-1056/ad01a7 摘要 ( 140 )   HTML ( 1 )   PDF(6489KB) ( 90 )   The formation of low-resistance Ohmic contacts in Ga2O3 is crucial for high-performance electronic devices. Conventionally, a titanium/gold (Ti/Au) electrode is rapidly annealed to achieve Ohmic contacts, resulting in mutual diffusion of atoms at the interface. However, the specific role of diffusing elements in Ohmic contact formation remains unclear. In this work, we investigate the contribution of oxygen atom diffusion to the formation of Ohmic contacts in Ga2O3. We prepare a Ti/Au electrode on a single crystal substrate and conduct a series of electrical and structural characterizations. Using density functional theory, we construct a model of the interface and calculate the charge density, partial density of states, planar electrostatic potential energy, and I—V characteristics. Our results demonstrate that the oxygen atom diffusion effectively reduces the interface barrier, leading to low-resistance Ohmic contacts in Ga2O3. These findings provide valuable insights into the underlying mechanisms of Ohmic contact formation and highlight the importance of considering the oxygen atom diffusion in the design of Ga2O3-based electronic devices. 参考文献 | 相关文章 | 计量指标

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Resistive switching behavior and mechanism of HfOx films with large on/off ratio by structure design Xianglin Huang(黄香林), Ying Wang(王英), Huixiang Huang(黄慧香), Li Duan(段理), and Tingting Guo(郭婷婷) 2024 (1):  17303-17303.  doi: 10.1088/1674-1056/ad053a 摘要 ( 136 )   HTML ( 2 )   PDF(2338KB) ( 62 )   Different bilayer structures of HfOx/Ti(TiOx) are designed for hafnium-based memory to investigate the switching characteristics. The chemical states in the films and near the interface are characterized by x-ray photoelectron spectroscopy, and the oxygen vacancies are analyzed. Highly improved on/off ratio (～104) and much uniform switching parameters are observed for bilayer structures compared to single layer HfOx sample, which can be attributed to the modulation of oxygen vacancies at the interface and better control of the growth of filaments. Furthermore, the reliability of the prepared samples is investigated. The carrier conduction behaviors of HfOx-based samples can be attributed to the trapping and de-trapping process of oxygen vacancies and a filamentary model is proposed. In addition, the rupture of filaments during the reset process for the bilayer structures occur at the weak points near the interface by the recovery of oxygen vacancies accompanied by the variation of barrier height. The re-formation of fixed filaments due to the residual filaments as lightning rods results in the better switching performance of the bilayer structure. 参考文献 | 相关文章 | 计量指标

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Electrically controllable spin filtering in zigzag phosphorene nanoribbon based normal—antiferromagnet—normal junctions Ruigang Li(李锐岗), Jun-Feng Liu(刘军丰), and Jun Wang(汪军) 2024 (1):  17304-17304.  doi: 10.1088/1674-1056/acf82a 摘要 ( 124 )   HTML ( 0 )   PDF(1941KB) ( 66 )   We investigated the electric controllable spin-filtering effect in a zigzag phosphorene nanoribbon (ZPNR) based normal—antiferromagnet—normal junction. Two ferromagnets are closely coupled to the edges of the nanoribbon and form the edge-to-edge antiferromagnetism. Under an in-plane electric field, the two degenerate edge bands of the edge-to-edge antiferromagnet split into four spin-polarized sub-bands and a 100% spin-polarized current can be easily induced with the maximal conductance 2e2/h. The spin polarization changes with the strength of the electric field and the exchange field, and changes sign at opposite electric fields. The spin-polarized current switches from one edge to the other by reversing the direction of the electric field. The edge current can also be controlled spatially by changing the electric potential of the scattering region. The manipulation of edge current is useful in spin-transfer-torque magnetic random-access memory and provides a practical way to develop controllable spintronic devices. 参考文献 | 相关文章 | 计量指标

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Electric modulation of the Fermi arc spin transport via three-terminal configuration in topological semimetal nanowires Guang-Yu Zhu(祝光宇), Ji-Ai Ning(宁纪爱), Jian-Kun Wang(王建坤), Xin-Jie Liu(刘心洁), Jia-Jie Yang(杨佳洁), Ben-Chuan Lin(林本川), and Shuo Wang(王硕) 2024 (1):  17305-17305.  doi: 10.1088/1674-1056/ace157 摘要 ( 145 )   HTML ( 10 )   PDF(617KB) ( 74 )   Spin—momentum locking is a key feature of the topological surface state, which plays an important role in spintronics. The electrical detection of current-induced spin polarization protected by the spin—momentum locking in nonmagnetic systems provides a new platform for developing spintronics, while previous studies were mostly based on magnetic materials. In this study, the spin transport measurement of Dirac semimetal Cd3As2 was studied by three-terminal geometry, and a hysteresis loop signal with high resistance and low resistance state was observed. The hysteresis was reversed by reversing the current direction, which illustrates the spin—momentum locking feature of Cd3As2. Furthermore, we realized the on—off states of the spin signals through electric modulation of the Fermi arc via the three-terminal configuration, which enables the great potential of Cd3As2 in spin field-effect transistors. 参考文献 | 相关文章 | 计量指标

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Distinct behavior of electronic structure under uniaxial strain in BaFe2As2 Jiajun Li(李佳俊), Giao Ngoc Phan, Xingyu Wang(王兴玉), Fazhi Yang(杨发枝), Quanxin Hu(胡全欣), Ke Jia(贾可), Jin Zhao(赵金), Wenyao Liu(刘文尧), Renjie Zhang(张任杰), Youguo Shi(石友国), Shiliang Li(李世亮), Tian Qian(钱天), and Hong Ding(丁洪) 2024 (1):  17401-17401.  doi: 10.1088/1674-1056/acd8af 摘要 ( 168 )   HTML ( 9 )   PDF(1212KB) ( 79 )   We report a study of the electronic structure of BaFe2As2 under uniaxial strains using angle-resolved photoemission spectroscopy and transport measurements. Two electron bands at the MY point, with an energy splitting of 50 meV in the strain-free sample, shift downward and merge into each other under a large uniaxial strain, while three hole bands at the $\varGamma$ point shift downward together. However, we also observed an enhancement of the resistance anisotropy under uniaxial strains by electrical transport measurements, implying that the applied strains strengthen the electronic nematic order in BaFe2As2. These observations suggest that the splitting of these two electron bands at the MY point is not caused by the nematic order in BaFe2As2. 参考文献 | 相关文章 | 计量指标

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Enhanced conductivity and weakened magnetism in Pb-doped Sr2IrO4 Zhi-Lai Yue(岳智来), Wei-Li Zhen(甄伟立), Rui Niu(牛瑞), Ke-Ke Jiao(焦珂珂), Wen-Ka Zhu(朱文卡), Li Pi(皮雳), and Chang-Jin Zhang(张昌锦) 2024 (1):  17402-17402.  doi: 10.1088/1674-1056/ad08a9 摘要 ( 141 )   HTML ( 9 )   PDF(2658KB) ( 138 )   Group IV element Pb has been selected as the dopant to dope at the Sr site of Sr2IrO4. It is exciting to find that the single-phase crystal structure could be maintained with a high Pb doping level of up to x=0.3 in Sr2-xPbxIrO4. The mapping data obtained from energy-dispersive x-ray spectroscopy analyses give solid evidence that the Pb ions are uniformly distributed in the Sr2IrO4 matrix. The incorporation of Pb leads to a moderate depression of the canted antiferromagnetic ordering state. The electrical conductivity could be greatly enhanced when the Pb doping content is higher than x=0.2. The present results give a fresh material base to explore new physics in doped Sr2IrO4 systems. 参考文献 | 相关文章 | 计量指标

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Majorana tunneling in a one-dimensional wire with non-Hermitian double quantum dots Peng-Bin Niu(牛鹏斌) and Hong-Gang Luo(罗洪刚) 2024 (1):  17403-17403.  doi: 10.1088/1674-1056/ad0145 摘要 ( 152 )   HTML ( 0 )   PDF(1375KB) ( 42 )   The combination of non-Hermitian physics and Majorana fermions can give rise to new effects in quantum transport systems. In this work, we investigate the interplay of PT-symmetric complex potentials, Majorana tunneling and interdot tunneling in a non-Hermitian double quantum dots system. It is found that in the weak-coupling regime the Majorana tunneling has pronounced effects on the transport properties of such a system, manifested as splitting of the single peak into three and a reduced 1/4 peak in the transmission function. In the presence of the PT-symmetric complex potentials and interdot tunneling, the 1/4 central peak is robust against them, while the two side peaks are tuned by them. The interdot tunneling only induces asymmetry, instead of moving the conductance peak, due to the robustness of the Majorana modes. There is an exceptional point induced by the union of Majorana tunneling and interdot tunneling. With increased PT-symmetric complex potentials, the two side peaks will move towards each other. When the exceptional point is passed through, these two side peaks will disappear. In the strong-coupling regime, the Majorana fermion induces a 1/4 conductance dip instead of the three-peak structure. PT-symmetric complex potentials induce two conductance dips pinned at the exceptional point. These effects should be accessible in experiments. 参考文献 | 相关文章 | 计量指标

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Tunable dispersion relations manipulated by strain in skyrmion-based magnonic crystals Zhao-Nian Jin(金兆年), Xuan-Lin He(何宣霖), Chao Yu(于超), Henan Fang(方贺男), Lin Chen(陈琳), and Zhi-Kuo Tao(陶志阔) 2024 (1):  17501-17501.  doi: 10.1088/1674-1056/acf03c 摘要 ( 153 )   HTML ( 0 )   PDF(1732KB) ( 58 )   We theoretically investigate the propagation characteristics of spin waves in skyrmion-based magnonic crystals. It is found that the dispersion relation can be manipulated by strains through magneto-elastic coupling. Especially, the allowed bands and forbidden bands in dispersion relations shift to higher frequency with strain changing from compressive to tensile, while shifting to lower frequency with strain changing from tensile to compressive. We also confirm that the spin wave with specific frequency can pass the magnonic crystal or be blocked by tuning the strains. The result provides an advanced platform for studying the tunable skyrmion-based spin wave devices. 参考文献 | 相关文章 | 计量指标

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Magnetic and electronic properties of La-doped hexagonal 4H-SrMnO3 Jie Li(李杰), Yinan Chen(陈一楠), Nuo Gong(宫诺), Xin Huang(黄欣), Zhihong Yang(杨志红), and Yakui Weng(翁亚奎) 2024 (1):  17502-17502.  doi: 10.1088/1674-1056/acf995 摘要 ( 140 )   HTML ( 1 )   PDF(1197KB) ( 49 )   As typical strongly correlated electronic materials, manganites show rich magnetic phase diagrams and electronic structures depending on the doped carrier density. Most previous relevant studies of doped manganites rely on the cubic/orthorhombic structures, while the hexagonal structure is much less studied. Here first-principles calculations are employed to investigate the magnetic and electronic structures of La-doped 4H-SrMnO3. By systematically analyzing the two kinds of La-doped positions, our calculations predict that the doped electron with lattice distortion would prefer to form polarons, which contribute to the local magnetic phase transition, nonzero net magnetization, and semiconducting behavior. In addition, the energy gap decreases gradually with increasing doping concentration, indicating a tendency of insulator—metal transition. 参考文献 | 相关文章 | 计量指标

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Controllable high Curie temperature through 5d transition metal atom doping in CrI3 Xuebing Peng(彭雪兵), Mingsu Si(司明苏), and Daqiang Gao(高大强) 2024 (1):  17503-17503.  doi: 10.1088/1674-1056/ad053b 摘要 ( 144 )   HTML ( 0 )   PDF(1842KB) ( 33 )   Two-dimensional (2D) CrI3 is a ferromagnetic semiconductor with potential for applications in spintronics. However, its low Curie temperature (Tc) hinders realistic applications of CrI3. Based on first-principles calculations, 5d transition metal (TM) atom doping of CrI3 (TM@CrI3) is a universally effective way to increase Tc, which stems from the increased magnetic moment induced by doping with TM atoms. Tc of W@CrI3 reaches 254 K, nearly six times higher than that of the host CrI3. When the doping concentration of W atoms is increased to above 5.9%, W@CrI3 shows room-temperature ferromagnetism. Intriguingly, the large magnetic anisotropy energy of W@CrI3 can stabilize the long-range ferromagnetic order. Moreover, TM@CrI3 has a strong ferromagnetic stability. All TM@CrI3 change from a semiconductor to a half-metal, except doping with Au atom. These results provide information relevant to potential applications of CrI3 monolayers in spintronics. 参考文献 | 补充材料 | 相关文章 | 计量指标

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Stacking-dependent exchange bias in two-dimensional ferromagnetic/antiferromagnetic bilayers Huiping Li(李慧平), Shuaiwei Pan(潘帅唯), Zhe Wang(王喆), Bin Xiang(向斌), and Wenguang Zhu(朱文光) 2024 (1):  17504-17504.  doi: 10.1088/1674-1056/ad053d 摘要 ( 147 )   HTML ( 0 )   PDF(2693KB) ( 83 )   A clear microscopic understanding of exchange bias is crucial for its application in magnetic recording, and further progress in this area is desired. Based on the results of our first-principles calculations and Monte Carlo simulations, we present a theoretical proposal for a stacking-dependent exchange bias in two-dimensional compensated van der Waals ferromagnetic/antiferromagnetic bilayer heterostructures. The exchange bias effect emerges in stacking registries that accommodate inhomogeneous interlayer magnetic interactions between the ferromagnetic layer and different spin sublattices of the antiferromagnetic layer. Moreover, the on/off switching and polarity reversal of the exchange bias can be achieved by interlayer sliding, and the strength can be modulated using an external electric field. Our findings push the limits of exchange bias systems to extreme bilayer thickness in two-dimensional van der Waals heterostructures, potentially stimulating new experimental investigations and applications. 参考文献 | 补充材料 | 相关文章 | 计量指标

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Shape and diffusion instabilities of two non-spherical gas bubbles under ultrasonic conditions Wurihan Bao(包乌日汗) and De-Xin Wang(王德鑫) 2024 (1):  17803-17803.  doi: 10.1088/1674-1056/acfa81 摘要 ( 107 )   HTML ( 2 )   PDF(11625KB) ( 66 )   Ultrasonic cavitation involves dynamic oscillation processes induced by small bubbles in a liquid under the influence of ultrasonic waves. This study focuses on the investigation of shape and diffusion instabilities of two bubbles formed during cavitation. The derived equations for two non-spherical gas bubbles, based on perturbation theory and the Bernoulli equation, enable the analysis of their shape instability. Numerical simulations, utilizing the modified Keller—Miksis equation, are performed to examine the shape and diffusion instabilities. Three types of shape instabilities, namely, Rayleigh—Taylor, Rebound, and parametric instabilities, are observed. The results highlight the influence of initial radius, distance, and perturbation parameter on the shape and diffusion instabilities, as evidenced by the R0—Pa phase diagram and the variation pattern of the equilibrium curve. This research contributes to the understanding of multiple bubble instability characteristics, which has important theoretical implications for future research in the field. Specifically, it underscores the significance of initial bubble parameters, driving pressure, and relative gas concentration in determining the shape and diffusive equilibrium instabilities of non-spherical bubbles. 参考文献 | 相关文章 | 计量指标

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Epitaxial growth of ultrathin gallium films on Cd(0001) Zuo Li(李佐), Mingxia Shi(石明霞), Gang Yao(姚钢), Minlong Tao(陶敏龙), and Junzhong Wang(王俊忠) 2024 (1):  18101-18101.  doi: 10.1088/1674-1056/acfb7a 摘要 ( 155 )   HTML ( 6 )   PDF(1375KB) ( 87 )   Growth and electronic properties of ultrathin Ga films on Cd(0001) are investigated by low-temperature scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. It is found that Ga films exhibit the epitaxial growth with the pseudomorphic 1×1 lattice. The Ga islands deposited at 100 K show a ramified shape due to the suppressed edge diffusion and corner crossing. Furthermore, the majority of Ga islands reveal flat tops and a preferred height of three atomic layers, indicating the electronic growth at low temperature. Annealing to room temperature leads to not only the growth mode transition from electronic growth to conventional Stranski—Krastanov growth, but also the shape transition from ramified islands to smooth compact islands. Scanning tunneling spectroscopy (STS) measurements reveal that the Ga monolayer exhibits metallic behavior. DFT calculations indicate that all the interfacial Ga atoms occupy the energetically favorable hcp-hollow sites of the substrate. The charge density difference analysis demonstrates that the charge transfer from the Cd substrate to the Ga atoms is negligible, and there is weak interaction between Ga atoms and the Cd substrate. These results shall shed important light on fabrication of ultrathin Ga films on metal substrates with novel physical properties. 参考文献 | 相关文章 | 计量指标

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High responsivity photodetectors based on graphene/WSe2 heterostructure by photogating effect Shuping Li(李淑萍), Ting Lei(雷挺), Zhongxing Yan(严仲兴), Yan Wang(王燕), Like Zhang(张黎可), Huayao Tu(涂华垚), Wenhua Shi(时文华), and Zhongming Zeng(曾中明) 2024 (1):  18501-18501.  doi: 10.1088/1674-1056/acfa84 摘要 ( 395 )   HTML ( 12 )   PDF(3677KB) ( 399 )   Graphene, with its zero-bandgap electronic structure, is a highly promising ultra-broadband light absorbing material. However, the performance of graphene-based photodetectors is limited by weak absorption efficiency and rapid recombination of photoexcited carriers, leading to poor photodetection performance. Here, inspired by the photogating effect, we demonstrated a highly sensitive photodetector based on graphene/WSe2 vertical heterostructure where the WSe2 layer acts as both the light absorption layer and the localized grating layer. The graphene conductive channel is induced to produce more carriers by capacitive coupling. Due to the strong light absorption and high external quantum efficiency of multilayer WSe2, as well as the high carrier mobility of graphene, a high photocurrent is generated in the vertical heterostructure. As a result, the photodetector exhibits ultra-high responsivity of 3.85×104 A/W and external quantum efficiency of 1.3×107%. This finding demonstrates that photogating structures can effectively enhance the sensitivity of graphene-based photodetectors and may have great potential applications in future optoelectronic devices. 参考文献 | 补充材料 | 相关文章 | 计量指标

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Quantitative analysis of the morphing wing mechanism of raptors: IMMU-based motion capture system and its application on gestures of a Falco peregrinus Di Tang(唐迪), Liwen Zhu(朱力文), Wenxi Shi(施文熙), Dawei Liu(刘大伟), Yin Yang(杨茵), Guorong Yao(姚国荣), Senxiang Yan(严森祥), Zhongyong Fan(范忠勇), Yiwei Lu(陆祎玮), and Siyu Wang(王思宇) 2024 (1):  18701-18701.  doi: 10.1088/1674-1056/ad0148 摘要 ( 126 )   HTML ( 0 )   PDF(3161KB) ( 36 )   This paper presented a novel tinny motion capture system for measuring bird posture based on inertial and magnetic measurement units that are made up of micromachined gyroscopes, accelerometers, and magnetometers. Multiple quaternion-based extended Kalman filters were implemented to estimate the absolute orientations to achieve high accuracy. Under the guidance of ornithology experts, the extending/contracting motions and flapping cycles were recorded using the developed motion capture system, and the orientation of each bone was also analyzed. The captured flapping gesture of the Falco peregrinus is crucial to the motion database of raptors as well as the bionic design. 参考文献 | 相关文章 | 计量指标

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Identifying influential spreaders in social networks: A two-stage quantum-behaved particle swarm optimization with Lévy flight Pengli Lu(卢鹏丽), Jimao Lan(揽继茂), Jianxin Tang(唐建新), Li Zhang(张莉), Shihui Song(宋仕辉), and Hongyu Zhu(朱虹羽) 2024 (1):  18901-18901.  doi: 10.1088/1674-1056/acd3e0 摘要 ( 158 )   HTML ( 0 )   PDF(783KB) ( 36 )   The influence maximization problem aims to select a small set of influential nodes, termed a seed set, to maximize their influence coverage in social networks. Although the methods that are based on a greedy strategy can obtain good accuracy, they come at the cost of enormous computational time, and are therefore not applicable to practical scenarios in large-scale networks. In addition, the centrality heuristic algorithms that are based on network topology can be completed in relatively less time. However, they tend to fail to achieve satisfactory results because of drawbacks such as overlapped influence spread. In this work, we propose a discrete two-stage metaheuristic optimization combining quantum-behaved particle swarm optimization with Lévy flight to identify a set of the most influential spreaders. According to the framework, first, the particles in the population are tasked to conduct an exploration in the global solution space to eventually converge to an acceptable solution through the crossover and replacement operations. Second, the Lévy flight mechanism is used to perform a wandering walk on the optimal candidate solution in the population to exploit the potentially unidentified influential nodes in the network. Experiments on six real-world social networks show that the proposed algorithm achieves more satisfactory results when compared to other well-known algorithms. 参考文献 | 相关文章 | 计量指标

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Pedestrian flow through exit: Study focused on evacuation pattern Bo-Si Zhang(张博思), Zhi-Hong Yu(余志红), Bo-Lin Sun(孙柏林), Zi-Yu Guo(郭紫钰), and Mo Chen(陈默) 2024 (1):  18902-18902.  doi: 10.1088/1674-1056/acf494 摘要 ( 135 )   HTML ( 0 )   PDF(2856KB) ( 32 )   Experiments are conducted on the evacuation rate of pedestrians through exits with queued evacuation pattern and random evacuation pattern. The experimental results show that the flow rate of pedestrians is larger with the random evacuation pattern than with the queued evacuation pattern. Therefore, the exit width calculated based on the minimum evacuation clear width for every 100 persons, which is on the assumption that the pedestrians pass through the exit in one queue or several queues, is conservative. The number of people crossing the exit simultaneously is greater in the random evacuation experiments than in the queued evacuation experiments, and the time interval between the front row and rear row of people is shortened in large-exit conditions when pedestrians evacuate randomly. The difference between the flow rate with a queued evacuation pattern and the flow rate with a random evacuation pattern is related to the surplus width of the exit, which is greater than the total width of all accommodated people streams. Two dimensionless quantities are defined to explore this relationship. It is found that the difference in flow rate between the two evacuation patterns is stable at a low level when the surplus width of the exit is no more than 45% of the width of a single pedestrian stream. There is a great difference between the flow rate with the queued evacuation pattern and the flow rate with the random evacuation pattern in a scenario with a larger surplus width of the exit. Meanwhile, the pedestrians crowd extraordinarily at the exit in these conditions as well, since the number of pedestrians who want to evacuate through exit simultaneously greatly exceeds the accommodated level. Therefore, the surplus width of exit should be limited especially in the narrow exit condition, and the relationship between the two dimensionless quantities mentioned above could provide the basis to some extent. 参考文献 | 相关文章 | 计量指标

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Essential proteins identification method based on four-order distances and subcellular localization information Pengli Lu(卢鹏丽), Yu Zhong(钟雨), and Peishi Yang(杨培实) 2024 (1):  18903-18903.  doi: 10.1088/1674-1056/acd7ca 摘要 ( 126 )   HTML ( 0 )   PDF(1554KB) ( 11 )   Essential proteins are inseparable in cell growth and survival. The study of essential proteins is important for understanding cellular functions and biological mechanisms. Therefore, various computable methods have been proposed to identify essential proteins. Unfortunately, most methods based on network topology only consider the interactions between a protein and its neighboring proteins, and not the interactions with its higher-order distance proteins. In this paper, we propose the DSEP algorithm in which we integrated network topology properties and subcellular localization information in protein—protein interaction (PPI) networks based on four-order distances, and then used random walks to identify the essential proteins. We also propose a method to calculate the finite-order distance of the network, which can greatly reduce the time complexity of our algorithm. We conducted a comprehensive comparison of the DSEP algorithm with 11 existing classical algorithms to identify essential proteins with multiple evaluation methods. The results show that DSEP is superior to these 11 methods. 参考文献 | 相关文章 | 计量指标

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Analysis of radiation diffusion of COVID-19 driven by social attributes Fuzhong Nian(年福忠), Xiaochen Yang(杨晓晨), and Yayong Shi(师亚勇) 2024 (1):  18904-18904.  doi: 10.1088/1674-1056/acd7d1 摘要 ( 122 )   HTML ( 1 )   PDF(1000KB) ( 33 )   This paper first estimated the infectious capacity of COVID-19 based on the time series evolution data of confirmed cases in multiple countries. Then, a method to infer the cross-regional spread speed of COVID-19 was introduced in this paper, which took the gross domestic product (GDP) of each region as one of the factors that affect the spread speed of COVID-19 and studied the relationship between the GDP and the infection density of each region (mainland China, the United States, and EU countries). In addition, the geographic distance between regions was also considered in this method and the effect of geographic distance on the spread speed of COVID-19 was studied. Studies have shown that the probability of mutual infection of these two regions decreases with increasing geographic distance. Therefore, this paper proposed an epidemic disease spread index based on GDP and geographic distance to quantify the spread speed of COVID-19 in a region. The analysis results showed a strong correlation between the epidemic disease spread index in a region and the number of confirmed cases. This finding provides reasonable suggestions for the control of epidemics. Strengthening the control measures in regions with higher epidemic disease spread index can effectively control the spread of epidemics. 参考文献 | 相关文章 | 计量指标