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Thermal energy dependent transient permittivity of epsilon-near-zero material

Science China(physics,Mechanics & Astronomy) 2022年第8期65卷 96-101页

作者： Heng Wang Lixun Sun Kang Du Wending Zhang SooJin Chua Guixin Li Ting Mei MOE Key Laboratory of Material Physics and Chemistry under Extraordinary Conditions and Shaanxi Key Laboratory of Optical Information TechnologySchool of Physical Science and TechnologyNorthwestern Polytechnical UniversityXi’an710129China Department of Materials Science and Engineering Southern University of Science and TechnologyShenzhen518055China Shenzhen Institute for Quantum Science and Engineering Southern University of Science and TechnologyShenzhen518055China Department of Electrical and Computer Engineering National University of SingaporeSingapore117583Singapore LEES Program Singapore-MIT Alliance for Research&Technology(SMART)Singapore138602Singapore

Transparent conductive oxides exhibit attractive optical nonlinearity with ultrafast response and giant refractive index change near the epsilon-near-zero(ENZ) wavelength, originating from the intraband dynamics of conduction electrons. The optical nonlinearity of ENZ materials has been explained by using the overall-effective-mass and the overall-scattering-time of electrons in the extended Drude model. However, their response to optical excitation is yet the last building block to complete the theory. In this paper, the concept of thermal energy is theoretically proposed to account for the total energy of conduction electrons exceeding their thermal equilibrium value. The time-varying thermal energy is adopted to describe the transient optical response of indium-tin-oxide(ITO), a typical ENZ material. A spectrally-resolved femtosecond pump-probe experiment was conducted to verify our theory. By correlating the thermal energy with the pumping density, both the giant change and the transient response of the permittivity of ITO can be predicted. The results in this work provide a new methodology to describe the transient permittivities of ENZ materials, which will benefit the design of ENZ-based nonlinear photonic devices.

关键词： epsilon-near-zero optical nonlinearity transient response thermal energy hot electron indium tin oxide

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The Impact of Hot Carrier Injection-Induced Device Degradation for Lower-Power FinFETs

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Journal of Electronic Materials 2023年第2期52卷 1391-1399页

作者： Chen, Yu-Lin Yeh, Wen-Kuan Hsu, Heng-Tung Chen, Ke-Horng Lien, Der-Hsien Lin, Wen-Chin Yu, Tien-Han Chiu, Yu-Sheng Godwinraj, D. Godfrey, D. Wu, Chien-Hung International College of Semiconductor Technology National Yang Ming Chiao Tung University Hsinchu Taiwan Graduate Degree Program of College of Electrical and Computer Engineering National Yang Ming Chiao Tung University Hsinchu Taiwan Institute of Electronics National Yang Ming Chiao Tung University Hsinchu Taiwan Institute of Microelectronics National Cheng Kung University Tainan Taiwan Department of ECE Amal Jyothi College of Engineering Kerala Kottayam India Department of Optoelectronics and Materials Engineering Chung Hua University Hsinchu Taiwan Department of Electronics and Communication Engineering Dayananda Sagar University Bengaluru India National Applied Research Laboratories Hsinchu Taiwan

The impact of hot carrier injection (HCI) on the performance of standard and low-VT FinFETs are investigated and benchmarked with each other. For this investigation, these FinFETs were fabricated with various gate lengths (L) from 16 to 36 nm. HCI-induced transconductance degradation in standard devices for gate length variations of 36 nm down to 16 nm was 75%, while it was 35% for low-VT devices. Similarly, the degradation of threshold voltage in standard devices for gate length variations of 36 nm down to 16 nm was 39%, while it was 36% for low-VT device. In this work, as the device is subject to HCI, we found that: (1) short-channel devices cause severe degradation on the threshold voltage and transconductance (gm) compared to long-channel devices, owing to the higher electric field for short-channel devices at the gate edge, (2) standard devices exhibit a more stable threshold voltage than that of low-VT power devices, since the TiN barrier layer prevents Al atom diffusion into the HfO2 layer, and (3) the transconductance efficiency of standard devices is better than that of low-VT power devices. Further, the lower-VT devices show lower transconductance degradation than standard devices. However, the transconductance degradation of the long-channel standard and low-VT devices are the same. Compared to short-channel low-VT devices, extended-channel standard devices are more immune to the HCI effect. © 2022, The Minerals, Metals & Materials Society.

关键词： Threshold voltage

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Control of chirality and directionality of nonlinear metasurface light source via twisting

arXiv

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arXiv 2024年

作者： Zhou, Huanyu Ni, Xueqi Lou, Beicheng Fan, Shanhui Cao, Yuan Tang, Haoning Department of Electrical Engineering and Computer Science University of California at Berkeley BerkeleyCA94720 United States Department of Physics National University of Singapore Singapore119077 Singapore Department of Applied Physics and Ginzton Laboratory Stanford University StanfordCA94305 United States School of Engineering and Applied Sciences Harvard University CambridgeMA02138 United States

Metasurfaces have revolutionized nonlinear and quantum light manipulation in the past decade, enabling the design of materials that can tune polarization, frequency, and direction of light simultaneously. However, tuning of metasurfaces is traditionally achieved by changing their microscopic structure, which does not allow in situ tuning and dynamic optimization of the metasurfaces. In this Letter, we explore the concept of twisted bilayer and tetralayer nonlinear metasurfaces, which offer rich tunability in its effective nonlinear susceptibilities. Using gold-based metasurfaces, we demonstrate that a number of different singularities of nonlinear susceptibilities can exist in the parameter space of twist angle and interlayer gap between different twisted layers. At the singularities, reflected/transmitted light from the nonlinear process (such as second-harmonic generation) can either become circularly polarized (for C points), or entirely vanish (for V points). By further breaking symmetries of the system, we can independently tune all aspects of the reflected and transmitted nonlinear emission, achieving unidirectional emission with full-Poincaré polarization tunability, a dark state (V-V point), or any other bidirectional output. Our work paves the way for multidimensional control of polarization and directionality in nonlinear light sources, opening new avenues in ultrafast optics, optical communication, sensing, and quantum optics. © 2024, CC BY.

关键词： Quantum optics

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Improved Radiation Estimation at High Energy Facility for Public Health

Improved Radiation Estimation at High Energy Facility for Pu...

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IEEE Annual Ubiquitous Computing, Electronics & Mobile Communication Conference (UEMCON)

作者： Jerry Cao-Xue Hongfang Zhang Adam Stavola Bence Budavari Chiman Kwan Hongyi Wu Jiang Li William G. Enloe High School Raleigh NC Department of Electrical and Computer Engineering Old Dominion University Norfolk VA Thomas Jefferson National Accelerator Facility Newport News VA Applied Research LLC Rockville MD Force Projection Sector Johs Hopkins University Applied Physics Laboratory Laurel MD Department of Electrical & Computer Engineering University of Arizona Tuscon AZ

ISBN: (数字)9798331540906

ISBN: (纸本)9798331540913

Long-term exposure to ionizing radiation can lead to the development of cancer and other potentially fatal diseases. Estimating radiation levels at high-energy particle accelerators is crucial for ensuring the safety of personnel, the public, and the environment. This paper explores the application of transformer neural networks, focusing on five different attention mechanisms—Full Attention, Prob Attention, AutoCorrelation, Fourier Attention, and Wavelet Attention—for estimating radiation levels at the Thomas Jefferson National Accelerator Facility (JLab). The goal is to improve the accuracy of radiation estimation by training models using data from key radiation sensors. Four hundred trials were conducted for each attention mechanism, and performance was evaluated using metrics including R 2 . The results demonstrated that Prob Attention and AutoCorrelation outperformed the other mechanisms, offering substantial improvements over previous models. These findings highlight the importance of selecting and fine-tuning attention mechanisms in transformers for complex time-series analysis tasks in radiation monitoring.

关键词： Wavelet transforms Training Radiation monitoring Attention mechanisms Time series analysis Estimation Transformers Sensors Safety Autocorrelation

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Quantifying the performance of approximate teleportation and quantum error correction via symmetric 2-PPT-extendible channels

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Physical Review A 2023年第1期107卷 012428-012428页

作者： Tharon Holdsworth Vishal Singh Mark M. Wilde Department of Physics University of Alabama at Birmingham Birmingham Alabama 35233 USA Hearne Institute for Theoretical Physics Department of Physics and Astronomy and Center for Computation and Technology Louisiana State University Baton Rouge Louisiana 70803 USA School of Applied and Engineering Physics Cornell University Ithaca New York 14850 USA School of Electrical and Computer Engineering Cornell University Ithaca New York 14850 USA

The ideal realization of quantum teleportation relies on having access to a maximally entangled state; however, in practice, such an ideal state is typically not available and one can instead only realize an approximate teleportation. With this in mind, we present a method to quantify the performance of approximate teleportation when using an arbitrary resource state. More specifically, after framing the task of approximate teleportation as an optimization of a simulation error over one-way local operations and classical communication (LOCC) channels, we establish a semidefinite relaxation of this optimization task by instead optimizing over the larger set of 2-PPT-extendible channels (where PPT denotes positive partial transpose). The main analytical calculations in our paper consist of exploiting the unitary covariance symmetry of the identity channel to establish a significant reduction of the computational cost of this latter optimization. Next, by exploiting known connections between approximate teleportation and quantum error correction, we also apply these concepts to establish bounds on the performance of approximate quantum error correction over a given quantum channel. Finally, we evaluate our bounds for various examples of resource states and channels.

关键词： Quantum channels Quantum error correction Quantum teleportation

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Characterizations of Second-order Nonlinear Optical Susceptibility for ϵ-phase Gallium Oxide

Characterizations of Second-order Nonlinear Optical Suscepti...

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2022 Compound Semiconductor Week, CSW 2022

作者： Zhou, Jingan Zhao, Xuan Xu, Rui Fu, Kai Li, Tao Xu, Mingfei He, Ziyi Robinson, Jacob T. Zhu, Hanyu Zhang, Xiaodong Zhao, Yuji Rice University Department of Electrical and Computer Engineering HoustonTX77005 United States Rice University Smalley-Curl Institute Applied Physics Graduate Program HoustonTX77005 United States Rice University Department of Materials Science and NanoEngineering HoustonTX77005 United States Arizona State University School of Electrical Computer and Energy Engineering TempeAZ85287 United States Suzhou Institute of Nano-tech and Nano-bionics CAS Key Laboratory of Nanodevices and Applications Suzhou215123 China

ISBN: (数字)9781665453400

ISBN: (纸本)9781665453400

In this work, we report the second-order nonlinear optical susceptibility χ(2) for epsilon phase Gallium Oxide (ϵ-Ga2O3) thin film on sapphire. ϵ-Ga2O3 exhibits hexagonal P63mc space group symmetry, which is a non-centrosymmetric structure with non-zero second order susceptibility. By focusing a pulsed laser beam on to a polished ϵ-Ga2O3 thin film, we collected the generated second harmonic photons with an ultra-sensitive femtowatt photodetector, obtaining effective second-order nonlinear optical susceptibility of χ(2) = 4.89×10-3 pm/V at wavelength of 800 nm. Two different measurement systems collecting reflected and transmitted photons were applied separately to make the result more convincing. The wavelength dependence from 790 nm to 900 nm and polarization dependence from TM mode to TE mode were measured as well. These results will be helpful for the design and fabrication of Ga2O3 based integrated photonics platform in the infrared-visible spectral range. © 2022 IEEE.

关键词： Gallium compounds

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Stabilization of an integrated laser with an 8 mL Fabry-Pérot optical reference cavity

Stabilization of an integrated laser with an 8 mL Fabry-Pér...

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2022 IEEE Photonics Society Summer Topicals Meeting Series, SUM 2022

作者： McLemore, Charles A. Guo, Joel Jin, Naijun Xiang, Chao Lee, Dahyeon Wu, Lue Jin, Warren Kelleher, Megan L. Mason, David Chang, Lin Feshali, Avi Paniccia, Mario Rakich, Peter T. Vahala, Kerry J. Diddams, Scott A. Bowers, John E. Quinlan, Franklyn University of Colorado Boulder Department of Physics BoulderCO80309 United States National Institute of Standards and Technology BoulderCO80305 United States University of California Department of Electrical and Computer Engineering Santa BarbaraCA93106 United States Yale University Department of Applied Physics New HavenCT06520 United States T.J. Watson Laboratory of Applied Physics California Institute of Technology PasadenaCA91125 United States Anello Photonics Santa ClaraCA United States University of Colorado Boulder Department of Electrical Computer and Energy Engineering BoulderCO80309 United States

We present an integrated laser locked to an 8 mL microfabricated optical reference cavity with 1 Hz integrated linewidth, sub-10-14 fractional frequency instability and thermal noise limited performance to 1 kHz offse... 详细信息

ISBN: (数字)9781665434898

ISBN: (纸本)9781665434898

关键词： Laser mirrors

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Optimizing Transformer-based Models for Radiation Estimation at High Energy Accelerator Facility

Optimizing Transformer-based Models for Radiation Estimation...

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IEEE Annual Ubiquitous Computing, Electronics & Mobile Communication Conference (UEMCON)

作者： Jackie Wei Hongfang Zhang Adam Stavola Bence Budavari Chiman Kwan Hongyi Wu Jiang Li Piedmont Hills High School San Jose CA Department of Electrical and Computer Engineering Old Dominion University Norfolk VA Thomas Jefferson National Accelerator Facility Newport News VA Applied Research LLC Rockville MD Force Projection Sector Johs Hopkins University Applied Physics Laboratory Laurel MD Department of Electrical & Computer Engineering University of Arizona Tuscon AZ

ISBN: (数字)9798331540906

ISBN: (纸本)9798331540913

At high energy accelerator facilities, it is important to control radiation exposure to ensure the safety of the staff and public. In this paper, we optimized various Transformer-based deep learning models to efficiently estimate radiation exposure at the Thomas Jefferson National Accelerator Facility (JLab). We explored the effects of utilizing various model embedding types and training with either channel dependence or independence. The models were trained and optimized on radiation, energy, current, and beam loss accounting data collected from sensors at JLab. Our results demonstrated that the Transformer-based model utilizing temporal embedding and channel dependence achieved the best performance with an average R 2 score of 0.771. To the best of our knowledge, this work represents the first attempt to explore transformer deep learning models for radiation estimation at JLab and showed potential to further improve radiation estimation performance.

关键词： Deep learning Training Estimation Focusing Channel estimation Transformers Mobile communication Data models Sensors Safety

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Elucidating the Role of the His-Purkinje System During Long QT Mediated Arrhythmias

Elucidating the Role of the His-Purkinje System During Long ...

引用

Annual Modeling and Simulation Conference (ANNSIM)

作者： Anthony Owusu-Mensah Omer Berenfeld Michel Audette Department of Electrical and Computer Engineering Old Dominion University Norfolk USA Center for Arrhythmia Research Internal Medicine Biomedical Engineering and Applied Physics University of Michigan Ann Arbor USA

Long QT type 2 (LQT2) is a cardiac disorder caused by mutations in the hERG gene, which can lead to life-threatening arrhythmias. However, the exact involvement of the His-Purkinje System (HPS) in LQT2-mediated arrhythmias remains elusive. We utilized a computational model of the rabbit ventricles integrated with HPS to investigate the role of HPS in LQT2-mediated arrhythmia. We induced persistent reentry from an ectopic stimulus and isolated the HPS at different time points following the induction of reentry to determine its involvement in reentry dynamics. The earliest termination time for reentry coincided with the earliest time the HPS was isolated, indicating direct involvement of HPS in LQT2-mediated ventricular arrhythmia. Additionally, altering the HPS junctional parameters, such as coupling resistance or the number of myocytes at the Purkinje-Myocardial Junctions, affected reentry dynamics. Our multi-scale computer modeling outcomes offer important new understandings of probable arrhythmia mechanisms under LQT2 circumstances.

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Reducing Effective System Dimensionality with Long-Range Collective Dipole-Dipole Interactions

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Physical Review Letters 2024年第17期132卷 173803-173803页

作者： Ashwin K. Boddeti Yi Wang Xitlali G. Juarez Alexandra Boltasseva Teri W. Odom Vladimir Shalaev Hadiseh Alaeian Zubin Jacob Elmore Family School of Electrical and Computer Engineering Purdue University West Lafayette Indiana 47907 USA Birck Nanotechnology Center Purdue University West Lafayette Indiana 47907 USA Graduate Program in Applied Physics Northwestern University Evanston Illinois 60208 USA Department of Materials Science and Engineering Northwestern University Evanston Illinois 60208 USA Department of Chemistry Northwestern University Evanston Illinois 60208 USA School of Physics and Astronomy Purdue University West Lafayette Indiana 47907 USA

Dimensionality plays a crucial role in long-range dipole-dipole interactions (DDIs). We demonstrate that a resonant nanophotonic structure modifies the apparent dimensionality in an interacting ensemble of emitters, as revealed by population decay dynamics. Our measurements on a dense ensemble of interacting quantum emitters in a resonant nanophotonic structure with long-range DDIs reveal an effective dimensionality reduction to d¯=2.20(12), despite the emitters being distributed in 3D. This contrasts with the homogeneous environment, where the apparent dimension is d¯=3.00. Our work presents a promising avenue to manipulate dimensionality in an ensemble of interacting emitters.

关键词： Light-matter interaction Long-range interactions Metamaterials Optics & lasers Photonics Plasmonics Quantum optics

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