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Chern-Protected Flatband Edge State in Metaphotonics

Physical Review Letters 2025年第22期134卷 223806-223806页

作者： Jianfeng Chen Yidong Zheng Shuihua Yang Andrea Alù Zhi-Yuan Li Cheng-Wei Qiu Department of Electrical and Computer Engineering National University of Singapore Singapore Singapore School of Physics and Optoelectronics South China University of Technology Guangzhou 510640 China Physics Program Graduate Center City University of New York New York New York 10016 USA Photonics Initiative Advanced Science Research Center City University of New York New York New York 10031 USA

Two-dimensional Dirac semimetals feature flatband edge states but a zero Chern number, while Chern insulators support one-way edge states associated with a nonzero Chern number. Here, we demonstrate a two-dimensional photonic crystal combining the response of a semimetal and of a Chern insulator, termed a Chern semimetal. This photonic semimetal is characterized by a nonzero Chern number, simultaneously hosting both a flatband edge state and a one-way edge state. We experimentally realize such a photonic Chern semimetal using a gyromagnetic photonic crystal with programmable magnetic bias, tailoring its second-neighbor coupling within each sublattice. We also verify the ability to control over the light speed while preserving topological protection. Our findings open new avenues toward exploring topological phases and their applications across fermionic and bosonic systems, providing an exciting platform for nanophotonic applications and a playground for topological physics discoveries.

关键词： Nanophotonics

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Graphene Terahertz Devices for Sensing and Communication

arXiv

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arXiv 2024年

作者： Samaha, Anna-Christina Doumani, Jacques Kritzell, T. Elijah Xu, Hongjing Baydin, Andrey Ajayan, Pulickel M. Tahchi, Mario El Kono, Junichiro Laboratory of Biomaterials and Intelligent Materials Department of Physics Faculty of Sciences 2 Lebanese University P.O. Box 90656 Jdeidet Lebanon Department of Electrical and Computer Engineering Rice University 6100 Main Street HoustonTX77005 United States Applied Physics Graduate Program Smalley–Curl Institute Rice University 6100 Main Street HoustonTX77005 United States Department of Physics and Astronomy Rice University 6100 Main Street HoustonTX77005 United States Smalley–Curl Institute Rice University 6100 Main Street HoustonTX77005 United States Department of Materials Science and NanoEngineering Rice University 6100 Main Street HoustonTX77005 United States Carbon Hub Rice University 6100 Main Street HoustonTX77005 United States

Graphene-based terahertz (THz) devices have emerged as promising platforms for a variety of applications, leveraging graphene’s unique optoelectronic properties. This review explores recent advancements in utilizing graphene in THz technology, focusing on two main aspects: THz molecular sensing and THz wave modulation. In molecular sensing, the environment-sensitive THz transmission and emission properties of graphene are utilized for enabling molecular adsorption detection and biomolecular sensing. This capability holds significant potential, from the detection of pesticides to DNA at high sensitivity and selectivity. In THz wave modulation, crucial for next-generation wireless communication systems, graphene demonstrates remarkable potential in absorption modulation when gated. Novel device structures, spectroscopic systems, and metasurface architectures have enabled enhanced absorption and wave modulation. Furthermore, techniques such as spatial phase modulation and polarization manipulation have been explored. From sensing to communication, graphene-based THz devices present a wide array of opportunities for future research and development. Finally, advancements in sensing techniques not only enhance biomolecular analysis but also contribute to optimizing graphene’s properties for communication by enabling efficient modulation of electromagnetic waves. Conversely, developments in communication strategies inform and enhance sensing capabilities, establishing a mutually beneficial relationship. © 2024, CC BY.

关键词： Graphene

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Evaluation of Frequency-Dependent Effects of Deep Brain Stimulation in a Cortex-Basal Ganglia-Thalamus Network Model of Parkinson’s Disease*

Evaluation of Frequency-Dependent Effects of Deep Brain Stim...

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Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBC)

作者： Marcelo R. Romano Renan C. Moioli Leonardo A. Elias Neural Engineering Research Laboratory School of Electrical and Computer Engineering University of Campinas Campinas SP Brazil Graduate Program in Bioinformatics Digital Metropolis Institute Federal University of Rio Grande do Norte Natal Brazil Center for Biomedical Engineering University of Campinas Campinas SP Brazil

ISBN: (数字)9781728119908

ISBN: (纸本)9781728119915

Parkinson's disease (PD) is a chronic neurodegenerative disease whose motor symptoms are accompanied by an exaggerated power in the alpha-beta (7-35Hz) band and an increased synchronization of neurons encompassing the cortex-basal ganglia-thalamus network. Currently, deep brain stimulation (DBS) is used as an effective therapy for reducing the excessive power and synchrony observed in brain circuits, thereby ameliorating the PD symptoms. In the present study, we used a biologically plausible computational model of cortex-basal ganglia-thalamus network, which represents both healthy and PD conditions, to systematically investigate the effects of DBS frequency on the model outputs. DBS was applied to the subthalamic nucleus (STN) at different stimulation frequencies (40Hz to 300Hz). Spike train variability and spectral power in the 7-35Hz band were measured from the several nuclei represented in the model. In addition, the magnitude squared coherence between the nuclei was assessed. An increased DBS frequency tended to produce interspike intervals (ISIs) with higher variability as compared to PD condition. Also, DBS significantly reduced the alpha-beta power for almost all brain nuclei. The median of the magnitude-squared coherence matrix (which is a metric of global network synchronization) decreased significantly with the increase of DBS frequency.

关键词： Satellite broadcasting Brain modeling Neurons Computational modeling Coherence Partial discharges Synchronization

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Terahertz cavity magnon polaritons

arXiv

引用

arXiv 2023年

作者： Kritzell, T. Elijah Baydin, Andrey Tay, Fuyang Rodriguez, Rodolfo Nojiri, Hiroyuki Everitt, Henry O. Barsukov, Igor Kono, Junichiro Department of Electrical and Computer Engineering Rice University HoustonTX77005 United States Applied Physics Graduate Program Smalley-Curl Institute Rice University HoustonTX77005 United States Smalley-Curl Institute Rice University HoustonTX77005 United States Physics and Astronomy University of California RiversideCA92521 United States Institute for Materials Research Tohoku University Sendai980-8577 Japan DEVCOM Army Research Laboratory-South HoustonTX77005 United States Department of Physics and Astronomy Rice University HoustonTX77005 United States Department of Material Science and NanoEngineering Rice University HoustonTX77005 United States

Hybrid light-matter coupled states, or polaritons, in magnetic materials have attracted significant attention due to their potential for enabling novel applications in spintronics and quantum information processing. However, most studies to date have been carried out for ferromagnetic materials with magnon excitations at gigahertz frequencies. Here, we have investigated strong resonant photon-magnon coupling at frequencies above 1 terahertz for the first time in a prototypical room-temperature antiferromagnetic insulator, NiO, inside a Fabry-Pérot cavity. The cavity was formed by the crystal itself when it was thinned down to an optimized thickness. By using terahertz time-domain spectroscopy in high magnetic fields up to 25 T, we swept the magnon frequency through Fabry-Pérot cavity modes and observed photon-magnon anticrossing behavior, demonstrating clear vacuum Rabi splittings exceeding the polariton linewidths. These results show that NiO is a promising platform for exploring antiferromagnetic spintronics and cavity magnonics in the terahertz frequency range. Copyright © 2023, The Authors. All rights reserved.

关键词： Polariton

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Ferroelectric transistors based on shear-transformation-mediated rhombohedral-stacked molybdenum disulfide

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Nature Electronics 2024年第1期7卷 29-38页

作者： Yang, Tilo H. Liang, Bor-Wei Hu, Hsiang-Chi Chen, Fu-Xiang Ho, Sheng-Zhu Chang, Wen-Hao Yang, Liu Lo, Han-Chieh Kuo, Tzu-Hao Chen, Jyun-Hong Lin, Po-Yen Simbulan, Kristan Bryan Luo, Zhao-Feng Chang, Alice Chinghsuan Kuo, Yi-Hao Ku, Yu-Seng Chen, Yi-Cheng Huang, You-Jia Chang, Yu-Chen Chiang, Yu-Fan Lu, Ting-Hua Lee, Min-Hung Li, Kai-Shin Wu, Menghao Chen, Yi-Chun Lin, Chun-Liang Lan, Yann-Wen Department of Physics National Taiwan Normal University Taipei Taiwan Taiwan Semiconductor Research Institute National Applied Research Laboratories Hsinchu Taiwan Department of Electrophysics National Yang Ming Chiao Tung University Hsinchu Taiwan Department of Physics National Cheng Kung University Tainan Taiwan School of Physics Huazhong University of Science and Technology Wuhan China Institute of Cellular and Organismic Biology Academia Sinica Taipei Taiwan Department of Mathematics and Physics University of Santo Tomas Manila Philippines Program for Semiconductor Devices Materials and Hetero-integration Graduate School of Advanced Technology National Taiwan University Taipei Taiwan Hsinchu Taiwan Department of Physics National Taiwan University Taipei Taiwan Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology CambridgeMA United States

To develop low-power, non-volatile computing-in-memory device using ferroelectric transistor technologies, ferroelectric channel materials with scaled thicknesses are required. Two-dimensional semiconductors, such as molybdenum disulfide (MoS2), equipped with sliding ferroelectricity could provide an answer. However, achieving switchable electric polarization in epitaxial MoS2 remains challenging due to the absence of mobile domain boundaries. Here we show that polarity-switchable epitaxial rhombohedral-stacked (3R) MoS2 can be used as a ferroelectric channel in ferroelectric memory transistors. We show that a shear transformation can spontaneously occur in 3R MoS2 epilayers, producing heterostructures with stable ferroelectric domains embedded in a highly dislocated and unstable non-ferroelectric matrix. This diffusionless phase transformation process produces mobile screw dislocations that enable collective polarity control of 3R MoS2 via an electric field. Polarization–electric-field measurements reveal a switching field of 0.036 V nm−1 for shear-transformed 3R MoS2. Our sliding ferroelectric transistors are non-volatile memory units with thicknesses of only two atomic layers and exhibit an average memory window of 7 V with an applied voltage of 10 V, retention times greater than 104 seconds and endurance greater than 104 cycles. © 2023, The Author(s), under exclusive licence to Springer Nature Limited.

关键词： Molybdenum disulfide

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Assessing Elevated Blood Glucose Levels Through Blood Glucose Evaluation and Monitoring Using Machine Learning and Wearable Photoplethysmography Sensors: Algorithm Development and Validation

TechRxiv

引用

TechRxiv 2022年

作者： Shi, Bohan Dhaliwal, Satvinder Singh Soo, Marcus Chan, Cheri Wong, Jocelin Lam, Natalie W.C. Zhou, Entong Paitimusa, Vivien Loke, Kum Yin Chin, Joel Chua, Mei Tuan Liaw, Kathy Chiew Suan Lim, Amos W.H. Insyirah, Fadil Fatin Yen, Shih-Cheng Tay, Arthur Ang, Seng Bin Actxa Pte Ltd Singapore Singapore Activate Interactive Pte Ltd Singapore Singapore Curtin Health Innovation Research Institute Curtin University Perth Australia Faculty of Health Sciences Curtin University Perth Australia Duke NUS Graduate Medical School National University of Singapore Singapore KK Women’s and Children’s Hospital Singapore Innovation and Design Programme Faculty of Engineering National University of Singapore Singapore Department of Electrical and Computer Engineering National University of Singapore Singapore Family Medicine Academic Clinical Program Duke-NUS Medical School Singapore Menopause Unit KK Women’s and Children’s Hospital Singapore

Background: Diabetes mellitus is the most challenging and fastest-growing global public health concern. Approximately 10.5% of the global adult population is affected by diabetes, and almost half of them are undiagnosed. The growing at-risk population exacerbates the shortage of health resources, with an estimated 10.6% and 6.2% of adults worldwide having impaired glucose tolerance and impaired fasting glycemia, respectively. All current diabetes screening methods are invasive and opportunistic and must be conducted in a hospital or laboratory by trained professionals. At-risk participants might remain undetected for years and miss the precious time window for early intervention to prevent or delay the onset of diabetes and its complications. Objective: We aimed to develop an artificial intelligence solution to recognize elevated blood glucose levels (≥7.8 mmol/L) noninvasively and evaluate diabetic risk based on repeated measurements. Methods: This study was conducted at KK Women’s and Children’s Hospital in Singapore, and 500 participants were recruited (mean age 38.73, SD 10.61 years;mean BMI 24.4, SD 5.1 kg/m2). The blood glucose levels for most participants were measured before and after consuming 75 g of sugary drinks using both a conventional glucometer (Accu-Chek Performa) and a wrist-worn wearable. The results obtained from the glucometer were used as ground-truth measurements. We performed extensive feature engineering on photoplethysmography (PPG) sensor data and identified features that were sensitive to glucose changes. These selected features were further analyzed using an explainable artificial intelligence approach to understand their contribution to our predictions. Results: Multiple machine learning models were trained and assessed with 10-fold cross-validation, using participant demographic data and critical features extracted from PPG measurements as predictors. A support vector machine with a radial basis function kernel had the best detection p

关键词： Wearable sensors

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DC-AC Multilevel T-type Isolated Three-Phase Indirect Matrix Inverter

DC-AC Multilevel T-type Isolated Three-Phase Indirect Matrix...

引用

European Conference on Power Electronics and Applications

作者： Ailton do E. Dutra Montiê A. Vitorino Maurício B. R. Corrêa Post-Graduate Program in Electrical Engineering (PPgEE-COPELE) FEDERAL UNIVERSITY OF CAMPINA GRANDE (UFCG) Campina Grande PB Brazil

In this work it is proposed a multilevel T-type configuration for a high-frequency pulsating DC-link inverter for three-phase applications. The configuration consists of two DC/DC-pulsating converters cascaded with a DC-link capacitor-less three-phase three-level T-type inverter. Due to the absence of DC-link electrolytic capacitors, the proposed inverter guarantees a long lifetime and high power density. The DC-DC-pulsating converters aim to generate the high-frequency pulsating DC-link waveform profiles which have to be synchronized with the three-phase inverter PWM. Comparing to the conventional PWM, the proposed technique presents reduced switching losses due to the fact only one leg commutes during a switching period while the other two legs keep clamped in high or low impedance. Details of control strategy and modulation are presented, such as experimental results to validate the theoretical approach.

关键词： Inverters Legged locomotion Europe Capacitors Pulse width modulation

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Three-Phase Integrated PFC AC-AC Resonant Inverter with Weak Coupled Coils for Induction Heating Application

Three-Phase Integrated PFC AC-AC Resonant Inverter with Weak...

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IEEE Energy Conversion Congress and Exposition

作者： Ruan C. M. Gomes Montie A. Vitorino Diego A. Acevedo-Bueno Mauricio B. R. Correa Post-Graduate Program in Electrical Engineering (PPgEE–COPELE) Federal University of Campina Grande (UFCG) Campina Grande PB Brazil

This paper proposes a 4.3 kW three-phase integrated PFC AC-AC resonant inverter for Induction Heating (IH) Application. This converter is composed by three independent resonant inverters with non-smoothed DC link that achieves high power factor operation. The magnetic coupling of the three coils was modeled by using the impedance matrix for characterizing the resonant behavior of the arrangement. The coils arrangement with weak coupling between coils is applied for induction water heater. Experimental results validate the modes of operation with ZVS and the converter performance in the entire power input range (PF and THD).

关键词： Coils DH-HEMTs Magnetic noise Magnetic resonance Magnetic shielding Couplings Impedance

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Four-Port AC/DC-DC/AC Dual Active Bridge Based Converter

Four-Port AC/DC-DC/AC Dual Active Bridge Based Converter

引用

European Conference on Power Electronics and Applications

作者： Diego A. Acevedo-Bueno José D. G. da Silva Jonatas R. Kinas Montiê A. Vitorino Antonio M. N. Lima Edison R. C. da Silva Alexandre C. Oliveira Post-Graduate Program in Electrical Engineering (PPgEE – COPELE) FEDERAL UNIVERSITY OF CAMPINA GRANDE (UFCG) Campina Grande PB Brazil

In this paper, a Four-Port AC/DC-DC/AC conversion system is proposed using two full-bridge converters and a high-frequency transformer following the principle of Dual Active Bridge Converter. Two full-bridge AC/DC single-phase converters are connected by coupling their boost inductance to create a high-frequency transformer of the resulting proposed converter. The isolated power transfer between converters is controlled by the duty cycles and the phase-shift applied to the primary and secondary of the split transformer. The boundaries of the switching modes and the power transferred through the high-frequency transformer were obtained analytically. The system feasibility was validated by simulations and by a 300 W prototype with 94.9% maximum efficiency.

关键词： Bridge circuits Inductance Europe Windings Magnetization Switches Boundary conditions

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Passive Bias-Free Nonreciprocal Metasurfaces Based on Nonlinear Quasi-Bound States in the Continuum

arXiv

引用

arXiv 2022年

作者： Cotrufo, Michele Cordaro, Andrea Sounas, Dimitrios L. Polman, Albert Alù, Andrea Photonics Initiative Advanced Science Research Center City University of New York New YorkNY10031 United States Van der Waals-Zeeman Institute Institute of Physics University of Amsterdam Science Park 904 Amsterdam1098 XH Netherlands Center for Nanophotonics AMOLF Science Park 104 Amsterdam1098 XG Netherlands Department of Electrical and Computer Engineering Wayne State University DetroitMI48202 United States Physics Program Graduate Center of the City University of New York New YorkNY10016 United States

Nonreciprocal devices – in which light is transmitted with different efficiencies along opposite directions – are key technologies for modern photonic applications, yet their compact and miniaturized implementation remains an open challenge. Among different avenues, nonlinearity-induced nonreciprocity has attracted significant attention due to the absence of external bias and integrability within conventional material platforms. So far, nonlinearity-induced nonreciprocity has been demonstrated only in guided platforms using high-Q resonators. Here, we demonstrate ultrathin optical metasurfaces with large nonreciprocal response for free-space radiation based on silicon third-order nonlinearities. Our metasurfaces combine an out-of-plane asymmetry – necessary to obtain nonreciprocity – with in-plane broken symmetry, which finely tunes the radiative linewidth of quasi-bound states in the continuum (q-BICs). Third-order nonlinearities naturally occurring in silicon, engaged by q-BICs, are shown to enable over 10 dB of nonreciprocal transmission while maintaining less than 3 dB in insertion loss. The demonstrated devices merge the field of nonreciprocity with ultrathin metasurface technologies, offering an exciting functionality for signal processing and routing, communications, and protection of high-power laser cavities. © 2022, CC BY.

关键词： High power lasers

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