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Manipulation of Valley-Pseudospin in 2d Wte2/CrI3 Van Der Waals Heterostructure by Magnetic Proximity Effect

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SSRN 2023年

作者： Zhang, Wenli Zhu, Haoran Zhang, Wenqi Wang, Jing Zhang, Tiantian Yang, Shiru Shao, Bin Zuo, Xu College of Electronic Information and Optical Engineering Nankai University Tianjin300350 China Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology Nankai University Tianjin300350 China Key Laboratory of Photoelectronic Thin Film Devices and Technology of Tianjin Tianjin300350 China Engineering Research Center of Thin Film Optoelectronics Technology Ministry of Education Tianjin300350 China

Lifting the valley degeneracy is an essential condition for exploiting the valley degrees of freedom to process and store information in valleytronics. The magnetic proximity effect (MPE) has been proven to be an effective method for introducing a magnetic field via interlayer exchange interaction, which can be conveniently achieved by two-dimensional (2D) van der Waals (vdW) heterostructure engineering. We have investigated the electronic properties and valley physics of 2D WTe2/CrI3 heterostructure using first-principles calculations. The results show that a significant valley splitting of 34.01 meV can be obtained in the WTe2/CrI3 heterostructure due to the simultaneous breaking of inversion and time-reversal symmetry, which sensitively depends on the atomic overlap of the projected position in the specific stacking model. In addition, we also show that the valley splitting can be enhanced by applying a vertical external electric field (E-field) or reducing the interlayer distance. More than that, it can be boosted by an order of magnitude (~ 115.25 meV) through Cr ion intercalation. This is attributed to that the self-intercalated Cr ion has ferromagnetic ordering and perpendicular magnetic anisotropy. This result provides fundamental insights and valuable guidance for the application of 2D WTe2/CrI3 heterostructure in novel spintronic and valleytronic devices. © 2023, The Authors. All rights reserved.

关键词： Degrees of freedom (mechanics)

Automatic acute ischemic stroke lesion segmentation using semi-supervised learning

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arXiv

arXiv 2019年

作者： Zhao, Bin Wu, Hong Liu, Guohua Cao, Chen Jin, Song Liu, Zhiyang Ding, Shuxue Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology College of Electronic Information and Optical Engineering Nankai University Tianjin300071 China School of Artificial Intelligence Guilin University of Electronic Technology Guilin Guangxi541004 China Key Laboratory for Cerebral Artery and Neural Degeneration of Tianjin Department of Medical Imaging Tianjin Huanhu Hospital Tianjin300350 China

Ischemic stroke is a common disease in the elderly population, which can cause long-term disability and even death. However, the time window for treatment of ischemic stroke in its acute stage is very short. To fast localize and quantitively evaluate the acute ischemic stroke (AIS) lesions, many deep-learning-based lesion segmentation methods have been proposed in the literature, where a deep convolutional neural network (CNN) was trained on hundreds of fully labeled subjects with accurate annotations of AIS lesions. Despite that high segmentation accuracy can be achieved, the accurate labels should be annotated by experienced clinicians, and it is therefore very time-consuming to obtain a large number of fully labeled subjects. In this paper, we propose a semi-supervised method to automatically segment AIS lesions in diffusion weighted images and apparent diffusion coefficient maps. By using a large number of weakly labeled subjects and a small number of fully labeled subjects, our proposed method is able to accurately detect and segment the AIS lesions. In particular, our proposed method consists of three parts: 1) a double-path classification net (DPC-Net) trained in a weakly-supervised way is used to detect the suspicious regions of AIS lesions;2) a pixel-level K-Means clustering algorithm is used to identify the hyperintensive regions on the DWIs;and 3) a region-growing algorithm combines the outputs of the DPC-Net and the K-Means to obtain the final precise lesion segmentation. In our experiment, we use 460 weakly labeled subjects and 15 fully labeled subjects to train and fine-tune the proposed method. By evaluating on a clinical dataset with 150 fully labeled subjects, our proposed method achieves a mean dice coefficient of 0.639, and a lesion-wise F1 score of 0.799. Copyright © 2019, The Authors. All rights reserved.

关键词： Deep neural networks

Autofocusing and Self-Healing Properties of Circular Mathieu Beam Carrying Orbital Angular Momentum

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SSRN 2024年

作者： Xu, Dongye Lu, Zehui Duan, Shaoxiang Zhang, Xu Lin, Wei Yao, Yuan Zhang, Hao Liu, Bo Institute of Modern Optics College of Electronic Information and Optical Engineering Nankai University Tianjin300350 China Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology Nankai University Tianjin300350 China Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology Nankai University Tianjin300350 China Southern Marine Science and Engineering Guangdong Laboratory Zhuhai519000 China

Abrupt autofocusing is defined as a phenomenon that the peak light intensity of an optical beam dramatically increases by several orders of magnitude while remaining low level near the focal point. As one new type of non-paraxial autofocusing light, the circular Mathieu beams (CMBs) exhibit flexible autofocusing features due to their tailorable parameters. In this work, the autofocusing and self-healing dynamics of CMBs carrying OAM have been investigated. The numerical results indicate that the autofocusing properties of CMBs are significantly affected by the topological charges and positions of optical vortices. Moreover, by embedding obstacles of diverse sizes in initial planes, we elaborately demonstrate the self-healing properties of CMBs in different cases. The experimental results are in good accordance with the numerical simulations. The work presented in this paper would be of significance for the generation of non-paraxial abruptly autofocusing beams and paves new way toward various applications such as optical communication, optical metrology and optical tweezer, etc. © 2024, The Authors. All rights reserved.

关键词： Optical communication

Tme: Temporal and Motion Enhancement for Action Recognition

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SSRN 2022年

作者： Wang, Hao Liu, Guohua Zhao, Bin Sensor Technology Intelligent System Lab College of Electronic Information and Optical Engineering Nankai University Tianjin300350 China School of Artificial Intelligence Guilin University of Electronic Technology Guangxi Guilin541004 China Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology Tianjin300350 China Engineering Research Center of Thin Film Optoelectronics Technology Ministry of Education Nankai University Tianjin300350 China

The key to video understanding is to capture temporal information. 3D CNNs can achieve good performance by directly fusing spatial and temporal features but are computationally intensive. Conventional 2D CNNs perform well in image recognition, but their inability to extract temporal features leads to poor performance in video action recognition. In this work, we aim to identify temporal relationships for video action recognition. To this end, we propose a temporal and motion enhancement (TME) module consisting of two submodules: multipath temporal enhancement(MTE) module and a long short-range Motion Enhancement(LSME) module. The MTE module consists of four paths: the residual path, temporal aggregation(TA) path, channel-wise temporal excitation(CTE) path and spatial-attention temporal excitation(STE) path. The residual path makes part of the information in the original activation accessible. The TA path employs convolution on the temporal dimension to characterize temporal representation. The CTE path rebuilds channelwise feature relationships in terms of the temporal aspect. The STE path introduces attention mechanisms and explores the temporal modeling. We aggregate features of different paths by splitting channels, which is efficient for model inference. The LSME module calculates feature-level temporal differences between long and short range frames, which enhances the motion-related features. The TME module is plug-and-play and can be inserted into 2D CNNs to form an effective TMENet with limited extra computational cost. The extensive experiments on several action recognition datasets, such as Kinetics400, Something-Something V1&V2, HMDB51, and UCF101, demonstrate that the TMENet achieves the state-of-the-art performance with high efficiency. The code will be released soon. © 2022, The Authors. All rights reserved.

关键词： Image recognition

Tme: Temporal and Motion Enhancement for Action Recognition

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SSRN 2021年

作者： Wang, Hao Zhao, Bin Liu, Guohua Sensor Technology Intelligent System Lab College of Electronic Information and Optical Engineering Nankai University Tianjin 300350 China School of Artificial Intelligence Guilin University of Electronic Technology Guangxi Guilin541004 China Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology Tianjin 300350 China Engineering Research Center of thin film optoelectronics technology Ministry of Education Nankai University Tianjin 300350 China

The key to video understanding is to capture temporal information. 3D CNNs can achieve good performance by directly fusing spatial and temporal features but are computationally intensive. Conventional 2D CNNs perform well in image recognition, but the inability to extract temporal features leads to poor performance in video action recognition. In this work, we aim to catch temporal relationships for video action recognition. To this end, we propose a Temporal and Motion Enhancement (TME) module consisting of two submodules: Multi-path Temporal Enhancement(MTE) module and Long Short-range Motion Enhancement(LSME) module. The MTE module consists of four paths: Residual path, Temporal Aggregation(TA) path, Channel-wise Temporal Excitation(CTE) path and Spatial-attention Temporal Excitation(STE) path. The Residual path makes part of the information in the original activation accessible. The TA path employs convolution on temporal dimension to characterize temporal representation. The CTE path rebuilds channel-wise feature relationships in terms of the temporal aspect. The STE path introduces attention mechanisms and explores the temporal modeling. We aggregate features of different paths by splitting channels, which is efficient for model inference. The LSME module calculates feature-level temporal differences between long and short range frames, which enhances the motion-related features. TME module is plug-and-play and can be inserted into 2D CNNs to form an effective TMENet with limited extra computational cost. The extensive experiments on several action recognition datasets, such as Kinetics400, Something-Something V1\&V2, HMDB51, and UCF101, demonstrate that the TMENet outperforms the state-of-the-art methods with high efficiency. Code will be released soon. © 2021, The Authors. All rights reserved.

关键词： Image recognition

Photoelectrochemical sensors based on heterogeneous nanostructures for in vitro diagnostics

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Biosensors and Bioelectronics: X 2022年 11卷

作者： Cao, Shengli Xie, Ziyu Xiao, Gang Sun, Xinyue Diao, He Zhou, Xin Yue, Zhao Department of Microelectronics Nankai University Tianjin300350 China Department of Traditional Chinese Medicine Tianjin Central Hospital of Gynecology Obstetrics Nankai University Tianjin300199 China Department of Pathophysiology Shanxi Medical University Taiyuan Taiyuan030001 China Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology Tianjin300350 China Smart Sensing Interdisciplinary Science Center of Nankai University Tianjin300350 China

In vitro diagnostics with biochemical sensors are one of the most important technologies for medical diagnosis and the examination of human health. With the improvement of people's living standards, the demand for in vitro diagnostics is increasing, and the requirements for the performance of biochemical sensors are also getting higher. Compared to other biochemical sensors, photoelectrochemical sensors based on heterogeneous nanostructures have excellent light absorption ability and electron transfer performance, and are powerful alternatives for the detection of chemical substances and biochemical molecules for in vitro diagnostics. And this is the main reason why they are a hot topic among relevant analytical methods. However, comprehensive and detailed analyses based on these sensors are rarely reported, especially for in vitro diagnostics, so a complete review of this field is necessary. This review outlines the advantages and disadvantages of various current sensors and further demonstrates the superiority of photoelectrochemical sensors based on heterogeneous nanostructures by comparison. In addition, a detailed classification, introduction of principles and analysis of synthesis methods of heterogeneous nanostructured photoelectrochemical sensors are presented. Based on the above analysis, a detailed description of the use of this type of sensor for in vitro diagnosis of inorganic and organic (micromolecules and macromolecules) molecules in recent years is presented. Predicting and combating relevant diseases are realized by in vitro detection of molecules. Finally, it paves the way for subsequent researchers in the process of realizing practical applications of photoelectrochemical sensing based on heterogeneous nanostructures. © 2022 The Authors

关键词： Nanostructures

Squeezing-enhanced parameter estimation with a hybrid spin-oscillator interferometer

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Physical Review A 2022年第2期106卷 022413-022413页

作者： X. N. Feng Jiahao Huang L. F. Wei Chaohong Lee Guangdong Provincial Key Laboratory of Quantum Metrology and Sensing & School of Physics and Astronomy Sun Yat-Sen University (Zhuhai Campus) Zhuhai 519082 China Information Quantum Technology Laboratory International Cooperation Research Center of China Communication and Sensor Networks for Modern Transportation School of Information Science and Technology Southwest Jiaotong University Chengdu 610031 China State Key Laboratory of Optoelectronic Materials and Technologies Sun Yat-Sen University (Guangzhou Campus) Guangzhou 510275 China

Inspired by the recent work [Nature (London) 521, 336 (2015)], we propose a scheme to suppress the backaction-induced dephasing of the spin state in a spin-oscillator system by squeezing the quantum fluctuation of the two-mode oscillator. We show specifically that squeezing either on a single mode individually or on both modes simultaneously could be used to effectively suppress spin dephasing. Therefore, with a spin-oscillator interferometer input by the spin-dependent squeezing cat state, the sensitivity of the rotational parameter estimation can be significantly enhanced. Given that various squeezings on the two-mode vibrations of the oscillator have been experimentally demonstrated, the proposal could provide a possibility to implement the sensitive parameter estimation, particularly in the ion-trap system.

关键词： Quantum entanglement Quantum metrology

Erratum:Growth of TlBa2Ca2Cu3O9 Epitaxial Thin Films by Two-Step Method in Argon[***.36(2019)057401]

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Chinese Physics Letters 2021年第2期38卷 118-118页

作者： Jian Xing Li-Tian Wang Xiao-Xin Gao Xue-Lian Liang Kai-Yong He Ting Xue Sheng-Hui Zhao Jin-Li Zhang Ming He Xin-Jie Zhao Shao-Lin Yan Pei Wang Lu Ji College of Electronic Information and Optical Engineering Nankai UniversityTianjin 300350China Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology Tianjin 300350China Key Laboratory of Photoelectronic Thin Film Devices and Technology of Tianjin Tianjin 300350China Beijing Institute of Radio Measurement Beijing 100854China

In Fig.2 of the article,[1]the figure caption should be“Rocking curve of the(006)peak of the Tl-1223 thin film”instead of“Rocking curve of the(003)peak of the Tl-1223 thin film”.The corresponding description of this figure should be“As shown in Fig.2,the full width at half maximum(FWHM)of the Tl-1223(006)reflection peak is only 0.58∘,which shows that the film possesses a good crystalline structure”,instead of“As shown in Fig.2,the FWHM of the Tl-1223(003)reflection peak is only 0.58∘,which shows that the film possesses a good crystalline structure”.

关键词： film Cu3O crystalline

Obvious Phase Transition Status Induced by He +-Ions Implantation in KTN Crystal

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SSRN 2021年

作者： Yang, Quanxin Li, Xiaojin Liu, Hongliang Zheng, Dahuai Akhmadaliev, Shavkat Zhou, Shengqiang Wu, Pengfei Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology Institute of Modern Optics Nankai University Tianjin300350 China State Key Laboratory of Crystal Materials Shandong University Jinan250100 China MOE Key Laboratory of Weak-Light Nonlinear Photonics TEDA Institute of Applied Physics Nankai University Tianjin300457 China Helmholtz-Zentrum Dresden-Rossendorf Institute of Ion Beam Physics and Materials Research Dresden01328 Germany Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology Nankai University Tianjin300350 China

We report on the formation of a critical ferroelectric state induced by the He+ ion implantation in potassium tantalate niobate crystal. An obvious phase change has been observed in the ion irradiated region, which is mostly related to the stable polarized nanometric regions formed during the ion implantation process. Under the irradiation of 2 MeV He+ ions, two distinguishable layers corresponding to different energy transfer modes (elastic nuclear collision and inelastic electronic collision, respectively) between the incident He + ions and the intrinsic lattices have been formed beneath the irradiated surface. Lattice dynamics before and after the ion implantation process are investigated by a confocal μ-Raman system. And the variations of typical Raman-active vibrational modes demonstrate the presence of lattice distortion in the irradiated region. X-ray diffraction experiments further suggest the uniform lattice elongation in this region. Piezo-response force characteristic measurements reveal the existence of stable polarized nanometric regions with more intense polarization and verify that the crystal with such a phase status possesses extraordinary microscopic disorders, which is different from the traditional ferroelectric or paraelectric phase. The ion implantation method provides a new approach to form a temperature-stable critical ferroelectric state in relaxor ferroelectric materials. Also, analyses of the modification on the lattice dynamics of the irradiated region can help us build a clear awareness of the physical essence of this critical state and the relaxor ferroelectricity. © 2021, The Authors. All rights reserved.

关键词： Ion implantation