We investigate the topological properties of a two-chain quantum ladder with uneven legs, i.e., the two chains differ in their periods by a factor of 2. Such an uneven ladder presents rich band structures classified by the closure of either direct or indirect bandgaps. It also provides opportunities to explore fundamental concepts concerning band topology and edge modes, including the difference of intracellular and intercellular Zak phases, and the role of the inversion symmetry (IS). We calculate the Zak phases of the two kinds and find excellent agreement with the dipole moment and extra charge accumulation. We also find that configurations with IS feature a pair of degenerate two-side edge modes emerging as the closure of the direct bandgap, while configurations without IS feature one-side edge modes emerging as not only the closure of both direct and indirect bandgaps but also within the band continuum. Furthermore, by projecting to the two sublattices, we find that the effective Bloch Hamiltonian corresponds to that of a generalized Su–Schrieffer–Heeger model or the Rice–Mele model whose hopping amplitudes depend on the quasimomentum. In this way, the topological phases can be efficiently extracted through winding numbers. We propose that uneven ladders can be realized by spin-dependent optical lattices and their rich topological characteristics can be examined by near future experiments.
{"title":"Topological phases and edge modes of an uneven ladder","authors":"Wen-Chuang Shang, Yi-Ning Han, Shimpei Endo, Chao Gao","doi":"10.1088/1674-1056/ad50c0","DOIUrl":"https://doi.org/10.1088/1674-1056/ad50c0","url":null,"abstract":"We investigate the topological properties of a two-chain quantum ladder with uneven legs, i.e., the two chains differ in their periods by a factor of 2. Such an uneven ladder presents rich band structures classified by the closure of either direct or indirect bandgaps. It also provides opportunities to explore fundamental concepts concerning band topology and edge modes, including the difference of intracellular and intercellular Zak phases, and the role of the inversion symmetry (IS). We calculate the Zak phases of the two kinds and find excellent agreement with the dipole moment and extra charge accumulation. We also find that configurations with IS feature a pair of degenerate two-side edge modes emerging as the closure of the direct bandgap, while configurations without IS feature one-side edge modes emerging as not only the closure of both direct and indirect bandgaps but also within the band continuum. Furthermore, by projecting to the two sublattices, we find that the effective Bloch Hamiltonian corresponds to that of a generalized Su–Schrieffer–Heeger model or the Rice–Mele model whose hopping amplitudes depend on the quasimomentum. In this way, the topological phases can be efficiently extracted through winding numbers. We propose that uneven ladders can be realized by spin-dependent optical lattices and their rich topological characteristics can be examined by near future experiments.","PeriodicalId":10253,"journal":{"name":"Chinese Physics B","volume":"80 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141883991","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Neural networks are becoming ubiquitous in various areas of physics as a successful machine learning (ML) technique for addressing different tasks. Based on ML technique, we propose and experimentally demonstrate an efficient method for state reconstruction of the widely used Sagnac polarization-entangled photon source. By properly modeling the target states, a multi-output fully connected neural network is well trained using only six of the sixteen measurement bases in standard tomography technique, and hence our method reduces the resource consumption without loss of accuracy. We demonstrate the ability of the neural network to predict state parameters with a high precision by using both simulated and experimental data. Explicitly, the mean absolute error for all the parameters is below 0.05 for the simulated data and a mean fidelity of 0.99 is achieved for experimentally generated states. Our method could be generalized to estimate other kinds of states, as well as other quantum information tasks.
作为解决不同任务的成功机器学习（ML）技术，神经网络在物理学的各个领域变得无处不在。基于 ML 技术，我们提出并通过实验演示了一种高效方法，用于重建广泛使用的萨格纳克偏振纠缠光子源的状态。通过对目标状态进行适当建模，一个多输出全连接神经网络只需使用标准层析技术中十六个测量基础中的六个就能得到良好的训练，因此我们的方法在不损失精度的情况下减少了资源消耗。我们利用模拟和实验数据证明了神经网络高精度预测状态参数的能力。明确地说，模拟数据中所有参数的平均绝对误差低于 0.05，而实验生成状态的平均保真度达到 0.99。我们的方法可以推广用于估计其他类型的状态以及其他量子信息任务。
{"title":"Machine-learning-assisted efficient reconstruction of the quantum states generated from the Sagnac polarization-entangled photon source","authors":"Menghui Mao, Wei Zhou, Xinhui Li, Ran Yang, Yan-Xiao Gong, Shi-Ning Zhu","doi":"10.1088/1674-1056/ad51f7","DOIUrl":"https://doi.org/10.1088/1674-1056/ad51f7","url":null,"abstract":"Neural networks are becoming ubiquitous in various areas of physics as a successful machine learning (ML) technique for addressing different tasks. Based on ML technique, we propose and experimentally demonstrate an efficient method for state reconstruction of the widely used Sagnac polarization-entangled photon source. By properly modeling the target states, a multi-output fully connected neural network is well trained using only six of the sixteen measurement bases in standard tomography technique, and hence our method reduces the resource consumption without loss of accuracy. We demonstrate the ability of the neural network to predict state parameters with a high precision by using both simulated and experimental data. Explicitly, the mean absolute error for all the parameters is below 0.05 for the simulated data and a mean fidelity of 0.99 is achieved for experimentally generated states. Our method could be generalized to estimate other kinds of states, as well as other quantum information tasks.","PeriodicalId":10253,"journal":{"name":"Chinese Physics B","volume":"171 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141867206","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In high temperature cuprate superconductors, it was found that the superfluid density decreases with the increase of hole doping. One natural question is whether there exists normal fluid in the superconducting state in the overdoped region. In this paper, we have carried out high-resolution ultra-low temperature laser-based angle-resolved photoemission measurements on a heavily overdoped Bi2212 sample with a Tc of 48 K. We find that this heavily overdoped Bi2212 remains in the strong coupling regime with 2Δ0/(kBTc) = 5.8. The single-particle scattering rate is very small along the nodal direction (∼5 meV) and increases as the momentum moves from the nodal to the antinodal regions. A hard superconducting gap opening is observed near the antinodal region with the spectral weight at the Fermi level fully suppressed to zero. The normal fluid is found to be negligibly small in the superconducting state of this heavily overdoped Bi2212. These results provide key information to understand the high Tc mechanism in the cuprate superconductors.
{"title":"Negligible normal fluid in superconducting state of heavily overdoped Bi2Sr2CaCu2O8+δ detected by ultra-low temperature angle-resolved photoemission spectroscopy","authors":"Chaohui Yin, Qinghong Wang, Yuyang Xie, Yiwen Chen, Junhao Liu, Jiangang Yang, Junjie Jia, Xing Zhang, Wenkai Lv, Hongtao Yan, Hongtao Rong, Shenjin Zhang, Zhimin Wang, Nan Zong, Lijuan Liu, Rukang Li, Xiaoyang Wang, Fengfeng Zhang, Feng Yang, Qinjun Peng, Zuyan Xu, Guodong Liu, Hanqing Mao, Lin Zhao, Xintong Li, Xingjiang Zhou","doi":"10.1088/1674-1056/ad51f8","DOIUrl":"https://doi.org/10.1088/1674-1056/ad51f8","url":null,"abstract":"In high temperature cuprate superconductors, it was found that the superfluid density decreases with the increase of hole doping. One natural question is whether there exists normal fluid in the superconducting state in the overdoped region. In this paper, we have carried out high-resolution ultra-low temperature laser-based angle-resolved photoemission measurements on a heavily overdoped Bi2212 sample with a <italic toggle=\"yes\">T</italic><sub>c</sub> of 48 K. We find that this heavily overdoped Bi2212 remains in the strong coupling regime with 2<italic toggle=\"yes\">Δ</italic><sub>0</sub>/(<italic toggle=\"yes\">k</italic><sub>B</sub> <italic toggle=\"yes\">T</italic><sub>c</sub>) = 5.8. The single-particle scattering rate is very small along the nodal direction (∼5 meV) and increases as the momentum moves from the nodal to the antinodal regions. A hard superconducting gap opening is observed near the antinodal region with the spectral weight at the Fermi level fully suppressed to zero. The normal fluid is found to be negligibly small in the superconducting state of this heavily overdoped Bi2212. These results provide key information to understand the high <italic toggle=\"yes\">T</italic><sub>c</sub> mechanism in the cuprate superconductors.","PeriodicalId":10253,"journal":{"name":"Chinese Physics B","volume":"208 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141867208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01DOI: 10.1088/1674-1056/ad5af0
Gang Wang, Jun-Hao Lin
Transmission electron microscopy (TEM) offers unparalleled atomic-resolution imaging of complex materials and heterogeneous structures. However, high-energy imaging electrons can induce structural damage, posing a challenge for electron-beam-sensitive materials. Cryogenic TEM (Cryo-TEM) has revolutionized structural biology, enabling the visualization of biomolecules in their near-native states at unprecedented detail. The low electron dose imaging and stable cryogenic environment in Cryo-TEM are now being harnessed for the investigation of electron-beam-sensitive materials and low-temperature quantum phenomena. Here, we present a systematic review of the interaction mechanisms between imaging electrons and atomic structures, illustrating the electron beam-induced damage and the mitigating role of Cryo-TEM. This review then explores the advancements in low-dose Cryo-TEM imaging for elucidating the structures of organic-based materials. Furthermore, we showcase the application of Cryo-TEM in the study of strongly correlated quantum materials, including the detection of charge order and novel topological spin textures. Finally, we discuss the future prospects of Cryo-TEM, emphasizing its transformative potential in unraveling the complexities of materials and phenomena across diverse scientific disciplines.
透射电子显微镜（TEM）可对复杂材料和异质结构进行无与伦比的原子分辨率成像。然而，高能成像电子会导致结构损坏，这对电子束敏感材料构成了挑战。低温 TEM（Cryo-TEM）给结构生物学带来了革命性的变化，它能以前所未有的细节观察到生物分子的近原态。低温 TEM 的低电子剂量成像和稳定的低温环境目前正被用于研究电子束敏感材料和低温量子现象。在此，我们将系统回顾成像电子与原子结构之间的相互作用机制，说明电子束诱发的损伤以及低温微电子能谱仪的缓解作用。然后，本综述探讨了低剂量 Cryo-TEM 成像在阐明有机基材料结构方面的进展。此外，我们还展示了 Cryo-TEM 在强相关量子材料研究中的应用，包括电荷秩序和新型拓扑自旋纹理的检测。最后，我们讨论了 Cryo-TEM 的未来前景，强调了它在揭示不同科学学科中材料和现象的复杂性方面的变革潜力。
{"title":"Cryogenic transmission electron microscopy on beam-sensitive materials and quantum science","authors":"Gang Wang, Jun-Hao Lin","doi":"10.1088/1674-1056/ad5af0","DOIUrl":"https://doi.org/10.1088/1674-1056/ad5af0","url":null,"abstract":"Transmission electron microscopy (TEM) offers unparalleled atomic-resolution imaging of complex materials and heterogeneous structures. However, high-energy imaging electrons can induce structural damage, posing a challenge for electron-beam-sensitive materials. Cryogenic TEM (Cryo-TEM) has revolutionized structural biology, enabling the visualization of biomolecules in their near-native states at unprecedented detail. The low electron dose imaging and stable cryogenic environment in Cryo-TEM are now being harnessed for the investigation of electron-beam-sensitive materials and low-temperature quantum phenomena. Here, we present a systematic review of the interaction mechanisms between imaging electrons and atomic structures, illustrating the electron beam-induced damage and the mitigating role of Cryo-TEM. This review then explores the advancements in low-dose Cryo-TEM imaging for elucidating the structures of organic-based materials. Furthermore, we showcase the application of Cryo-TEM in the study of strongly correlated quantum materials, including the detection of charge order and novel topological spin textures. Finally, we discuss the future prospects of Cryo-TEM, emphasizing its transformative potential in unraveling the complexities of materials and phenomena across diverse scientific disciplines.","PeriodicalId":10253,"journal":{"name":"Chinese Physics B","volume":"779 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141884092","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01DOI: 10.1088/1674-1056/ad50be
Dong-Sheng Wang
We develop universal quantum computing models that form a family of quantum von Neumann architectures, with modular units of memory, control, CPU, and internet, besides input and output. This family contains three generations characterized by dynamical quantum resource theory, and it also circumvents no-go theorems on quantum programming and control. Besides universality, such a family satisfies other desirable engineering requirements on system and algorithm design, such as modularity and programmability, hence serves as a unique approach to building universal quantum computers.
{"title":"A family of quantum von Neumann architecture","authors":"Dong-Sheng Wang","doi":"10.1088/1674-1056/ad50be","DOIUrl":"https://doi.org/10.1088/1674-1056/ad50be","url":null,"abstract":"We develop universal quantum computing models that form a family of quantum von Neumann architectures, with modular units of memory, control, CPU, and internet, besides input and output. This family contains three generations characterized by dynamical quantum resource theory, and it also circumvents no-go theorems on quantum programming and control. Besides universality, such a family satisfies other desirable engineering requirements on system and algorithm design, such as modularity and programmability, hence serves as a unique approach to building universal quantum computers.","PeriodicalId":10253,"journal":{"name":"Chinese Physics B","volume":"10 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141884094","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
X-ray sources with tunable energy spectra have a wide range of applications in different scenarios due to their different penetration depths. However, existing x-ray sources face difficulties in terms of energy regulation. In this paper, we present a scheme for tuning the energy spectrum of a betatron x-ray generated from a relativistic electron bunch oscillating in a plasma wakefield. The center energy of the x-ray source can be tuned from several keV to several hundred keV by changing the plasma density, thereby extending the control range by an order of magnitude. At different central energies, the brightness of the betatron radiation is in the range of 3.7 × 1022 to 5.5 × 1022 photons/(0.1%BW⋅s⋅mm2⋅mrad2) and the photon divergence angle is about 2 mrad. This high-brightness, energy-controlled betatron source could pave the way to a wide range of applications requiring photons of specific energy, such as phase-contrast imaging in medicine, non-destructive testing and material analysis in industry, and imaging in nuclear physics.
具有可调能谱的 X 射线源因其穿透深度不同而在不同场景中有着广泛的应用。然而，现有的 X 射线源在能量调节方面面临困难。在本文中，我们介绍了一种用于调节由等离子体唤醒场中振荡的相对论电子束产生的贝塔电子 X 射线能谱的方案。通过改变等离子体密度，X 射线源的中心能量可以从几 keV 调整到几百 keV，从而将控制范围扩大了一个数量级。在不同的中心能量下，贝塔强辐射的亮度范围为 3.7 × 1022 至 5.5 × 1022 光子/（0.1%BW⋅s⋅mm2⋅mrad2），光子发散角约为 2 mrad。这种高亮度、能量可控的贝塔电子光源可为需要特定能量光子的广泛应用铺平道路，例如医学中的相位对比成像、工业中的无损检测和材料分析以及核物理中的成像。
{"title":"Tunable energy spectrum betatron x-ray sources in a plasma wakefield","authors":"Chuan-Yi Xi, Yin-Ren Shou, Li-Qi Han, Abdughupur Ablimit, Xiao-Dan Liu, Yan-Ying Zhao, Jin-Qing Yu","doi":"10.1088/1674-1056/ad4531","DOIUrl":"https://doi.org/10.1088/1674-1056/ad4531","url":null,"abstract":"X-ray sources with tunable energy spectra have a wide range of applications in different scenarios due to their different penetration depths. However, existing x-ray sources face difficulties in terms of energy regulation. In this paper, we present a scheme for tuning the energy spectrum of a betatron x-ray generated from a relativistic electron bunch oscillating in a plasma wakefield. The center energy of the x-ray source can be tuned from several keV to several hundred keV by changing the plasma density, thereby extending the control range by an order of magnitude. At different central energies, the brightness of the betatron radiation is in the range of 3.7 × 10<sup>22</sup> to 5.5 × 10<sup>22</sup> photons/(0.1%BW⋅s⋅mm<sup>2</sup>⋅mrad<sup>2</sup>) and the photon divergence angle is about 2 mrad. This high-brightness, energy-controlled betatron source could pave the way to a wide range of applications requiring photons of specific energy, such as phase-contrast imaging in medicine, non-destructive testing and material analysis in industry, and imaging in nuclear physics.","PeriodicalId":10253,"journal":{"name":"Chinese Physics B","volume":"52 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141884114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01DOI: 10.1088/1674-1056/ad4631
Xueying Wu, Yue Zhao, Liming Li
We take phase modulation to create discrete phase-controlled sources and realize the super-bunching effect by a phase-correlated method. From theoretical and numerical simulations, we find the space translation invariance of the bunching effect is a key point for the ghost imaging realization. Experimentally, we create the orderly phase-correlated discrete sources which can realize high-visibility second-order ghost imaging than the result with chaotic sources. Moreover, some factors affecting the visibility of ghost image are discussed in detail.
{"title":"High-visibility ghost imaging with phase-controlled discrete classical light sources","authors":"Xueying Wu, Yue Zhao, Liming Li","doi":"10.1088/1674-1056/ad4631","DOIUrl":"https://doi.org/10.1088/1674-1056/ad4631","url":null,"abstract":"We take phase modulation to create discrete phase-controlled sources and realize the super-bunching effect by a phase-correlated method. From theoretical and numerical simulations, we find the space translation invariance of the bunching effect is a key point for the ghost imaging realization. Experimentally, we create the orderly phase-correlated discrete sources which can realize high-visibility second-order ghost imaging than the result with chaotic sources. Moreover, some factors affecting the visibility of ghost image are discussed in detail.","PeriodicalId":10253,"journal":{"name":"Chinese Physics B","volume":"31 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141577940","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01DOI: 10.1088/1674-1056/ad5aef
Haofei Zhuang, Qingyuan Zhang, Gehao Hu, Qingdong Wang, Libin Du
Strengthened directivity with higher-order side lobes can be generated by the transducer with a larger radius at a higher frequency. The multi-annular pressure distributions are displayed in the cross-section of the acoustic vortices (AVs) which are formed by side lobes. In the near field, particles can be trapped in the valley region between the two annuli of the pressure peak, and cannot be moved to the vortex center. In this paper, a trapping method based on a sector transducer array is proposed, which is characterized by the continuously variable topological charge (CVTC). This acoustic field can not only enlarge the range of particle trapping but also improve the aggregation degree of the trapped particles. In the experiments, polyethylene particles with a diameter of 0.2 mm are trapped into the multi-annular valleys by the AV with a fixed topological charge. Nevertheless, by applying the CVTC, particles outside the radius of the AV can cross the pressure peak successfully and move to the vortex center. Theoretical studies are also verified by the experimental particles trapping using the AV with the continuous variation of three topological charges, and suggest the potential application of large-scale particle trapping in biomedical engineering.
在较高频率下，较大半径的换能器可产生具有较高阶侧叶的强化指向性。多环形压力分布显示在由侧裂片形成的声漩涡（AV）的横截面上。在近场，颗粒会被困在压力峰的两个环形之间的谷区，无法移动到涡旋中心。本文提出了一种基于扇形换能器阵列的捕集方法，其特点是具有连续可变拓扑电荷（CVTC）。这种声场不仅能扩大颗粒的捕获范围，还能提高被捕获颗粒的聚集度。在实验中，直径为 0.2 毫米的聚乙烯颗粒被具有固定拓扑电荷的 AV 捕集到多环形谷中。然而，通过使用 CVTC，AV 半径以外的颗粒可以成功越过压力峰并移动到漩涡中心。利用三种拓扑电荷连续变化的 AV 进行的粒子捕获实验也验证了理论研究，并提出了大规模粒子捕获在生物医学工程中的潜在应用。
{"title":"Large-scale particle trapping by acoustic vortices with a continuously variable topological charge","authors":"Haofei Zhuang, Qingyuan Zhang, Gehao Hu, Qingdong Wang, Libin Du","doi":"10.1088/1674-1056/ad5aef","DOIUrl":"https://doi.org/10.1088/1674-1056/ad5aef","url":null,"abstract":"Strengthened directivity with higher-order side lobes can be generated by the transducer with a larger radius at a higher frequency. The multi-annular pressure distributions are displayed in the cross-section of the acoustic vortices (AVs) which are formed by side lobes. In the near field, particles can be trapped in the valley region between the two annuli of the pressure peak, and cannot be moved to the vortex center. In this paper, a trapping method based on a sector transducer array is proposed, which is characterized by the continuously variable topological charge (CVTC). This acoustic field can not only enlarge the range of particle trapping but also improve the aggregation degree of the trapped particles. In the experiments, polyethylene particles with a diameter of 0.2 mm are trapped into the multi-annular valleys by the AV with a fixed topological charge. Nevertheless, by applying the CVTC, particles outside the radius of the AV can cross the pressure peak successfully and move to the vortex center. Theoretical studies are also verified by the experimental particles trapping using the AV with the continuous variation of three topological charges, and suggest the potential application of large-scale particle trapping in biomedical engineering.","PeriodicalId":10253,"journal":{"name":"Chinese Physics B","volume":"60 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141571669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01DOI: 10.1088/1674-1056/ad51f4
Jiadong Dan, Cheng Zhang, Xiaoxu Zhao, N. Duane Loh
We present a method using Zernike moments for quantifying rotational and reflectional symmetries in scanning transmission electron microscopy (STEM) images, aimed at improving structural analysis of materials at the atomic scale. This technique is effective against common imaging noises and is potentially suited for low-dose imaging and identifying quantum defects. We showcase its utility in the unsupervised segmentation of polytypes in a twisted bilayer TaS2, enabling accurate differentiation of structural phases and monitoring transitions caused by electron beam effects. This approach enhances the analysis of structural variations in crystalline materials, marking a notable advancement in the characterization of structures in materials science.
{"title":"Symmetry quantification and segmentation in STEM imaging through Zernike moments","authors":"Jiadong Dan, Cheng Zhang, Xiaoxu Zhao, N. Duane Loh","doi":"10.1088/1674-1056/ad51f4","DOIUrl":"https://doi.org/10.1088/1674-1056/ad51f4","url":null,"abstract":"We present a method using Zernike moments for quantifying rotational and reflectional symmetries in scanning transmission electron microscopy (STEM) images, aimed at improving structural analysis of materials at the atomic scale. This technique is effective against common imaging noises and is potentially suited for low-dose imaging and identifying quantum defects. We showcase its utility in the unsupervised segmentation of polytypes in a twisted bilayer TaS<sub>2</sub>, enabling accurate differentiation of structural phases and monitoring transitions caused by electron beam effects. This approach enhances the analysis of structural variations in crystalline materials, marking a notable advancement in the characterization of structures in materials science.","PeriodicalId":10253,"journal":{"name":"Chinese Physics B","volume":"73 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141867205","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01DOI: 10.1088/1674-1056/ad50bd
Zhaowen Xu, Xue Bai, Jian Ma, Zhuangzhuang Wan, Chaoqun Wang
Quantitative relationship between nanosecond pulsed laser parameters and the characteristics of laser-generated ultrasonic waves in polycrystalline materials was evaluated. The high energy of the pulsed laser with a large irradiation spot simultaneously generated ultrasonic longitudinal and shear waves at the epicenter under the slight ablation regime. An optimized denoising technique based on wavelet thresholding and variational mode decomposition was applied to reduce noise in shear waves with a low signal-to-noise ratio. An approach for characterizing grain size was proposed using spectral central frequency ratio (SCFR) based on time-frequency analysis. The results demonstrate that the generation regime of ultrasonic waves is not solely determined by the laser power density; even at high power densities, a high energy with a large spot can generate an ultrasonic waveform dominated by the thermoelastic effect. This is ascribed to the intensification of the thermoelastic effect with the proportional increase in laser irradiation spot area for a given laser power density. Furthermore, both longitudinal and shear wave SCFRs are linearly related to grain size in polycrystalline materials; however, the shear wave SCFR is more sensitive to finer-grained materials. This study holds great significance for evaluating metal material properties using laser ultrasound.
{"title":"Quantitative analysis of laser-generated ultrasonic wave characteristics and their correlation with grain size in polycrystalline materials","authors":"Zhaowen Xu, Xue Bai, Jian Ma, Zhuangzhuang Wan, Chaoqun Wang","doi":"10.1088/1674-1056/ad50bd","DOIUrl":"https://doi.org/10.1088/1674-1056/ad50bd","url":null,"abstract":"Quantitative relationship between nanosecond pulsed laser parameters and the characteristics of laser-generated ultrasonic waves in polycrystalline materials was evaluated. The high energy of the pulsed laser with a large irradiation spot simultaneously generated ultrasonic longitudinal and shear waves at the epicenter under the slight ablation regime. An optimized denoising technique based on wavelet thresholding and variational mode decomposition was applied to reduce noise in shear waves with a low signal-to-noise ratio. An approach for characterizing grain size was proposed using spectral central frequency ratio (SCFR) based on time-frequency analysis. The results demonstrate that the generation regime of ultrasonic waves is not solely determined by the laser power density; even at high power densities, a high energy with a large spot can generate an ultrasonic waveform dominated by the thermoelastic effect. This is ascribed to the intensification of the thermoelastic effect with the proportional increase in laser irradiation spot area for a given laser power density. Furthermore, both longitudinal and shear wave SCFRs are linearly related to grain size in polycrystalline materials; however, the shear wave SCFR is more sensitive to finer-grained materials. This study holds great significance for evaluating metal material properties using laser ultrasound.","PeriodicalId":10253,"journal":{"name":"Chinese Physics B","volume":"34 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141883992","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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