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Valley-selective optical Stark effect probed by Kerr rotation

Physical Review B 2018年第4期97卷 045307-045307页

作者： Trevor LaMountain Hadallia Bergeron Itamar Balla Teodor K. Stanev Mark C. Hersam Nathaniel P. Stern Applied Physics Program Northwestern University Evanston Illinois 60208 USA Department of Materials Science and Engineering Northwestern University Evanston Illinois 60208 USA Department of Physics and Astronomy Northwestern University Evanston Illinois 60208 USA Department of Chemistry Northwestern University Evanston Illinois 60208 USA Department of Electrical Engineering and Computer Science Northwestern University Evanston Illinois 60208 USA

The ability to monitor and control distinct states is at the heart of emerging quantum technologies. The valley pseudospin in transition metal dichalcogenide (TMDC) monolayers is a promising degree of freedom for such control, with the optical Stark effect allowing for valley-selective manipulation of energy levels in WS2 and WSe2 using ultrafast optical pulses. Despite these advances, understanding of valley-sensitive optical Stark shifts in TMDCs has been limited by reflectance-based detection methods where the signal is small and prone to background effects. More sensitive polarization-based spectroscopy is required to better probe ultrafast Stark shifts for all-optical manipulation of valley energy levels. Here, we show time-resolved Kerr rotation to be a more sensitive probe of the valley-selective optical Stark effect in monolayer TMDCs. Compared to the established time-resolved reflectance methods, Kerr rotation is less sensitive to background effects. Kerr rotation provides a fivefold improvement in the signal-to-noise ratio of the Stark effect optical signal and a more precise estimate of the energy shift. This increased sensitivity allows for observation of an optical Stark shift in monolayer MoS2 that exhibits both valley and energy selectivity, demonstrating the promise of this method for investigating this effect in other layered materials and heterostructures.

关键词： Dielectric properties Excitons Semiconductors Transition metal dichalcogenides Kerr effect Reflectivity

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Improving indistinguishability of single photons from colloidal quantum dots using nanocavities

arXiv

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arXiv 2019年

作者： Saxena, Abhi Chen, Yueyang Ryou, Albert Sevilla, Carlos G. Xu, Peipeng Majumdar, Arka Electrical and Computer Engineering University of Washington SeattleWA98195 United States Department of Physics University of Washington SeattleWA98195 United States School of Natural Science Hampshire College AmherstMA01002 United States Laboratory of Infrared Materials and Devices Advanced Technology Research Institute Ningbo University Ningbo315211 China Key Laboratory of Photoelectric Detection Materials Devices of Zhejiang Province Ningbo315211 China

Colloidal quantum dots have garnered active research interest as quantum emitters due to their robust synthesis process and straightforward integration with nanophotonic platforms. However, obtaining indistinguishable photons from the colloidal quantum dots at room temperature is fundamentally challenging because they suffer from an extremely large dephasing rate. Here we propose an experimentally feasible method of obtaining indistinguishable single photons from an incoherently pumped solution-processed colloidal quantum dot coupled to a system of nanocavities. We show that by coupling a colloidal quantum dot to a pair of silicon nitride cavities, we can obtain comparable performance of a single photon source from colloidal quantum dots as other leading quantum emitters like defect centers and self-assembled quantum dots. Copyright © 2019, The Authors. All rights reserved.

关键词： Particle beams

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Phase Coexistence of Ferroelectric Vortices and Classical a1/a2 Domains in PbTiO3/SrTiO3 Superlattices.

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Microscopy and Microanalysis 2018年第S1期24卷 1638-1639页

作者： Christopher T. Nelson Zijian Hong Ajay K. Yadav Anoop R. Damodaran Shang-Lin Hsu James D. Clarkson Long-Qing Chen Lane W. Martin Ramamoorthy Ramesh Materials Science & Technology Division Oak Ridge National Laboratory Oak Ridge TN USA Department of Physics University of California Berkeley CA USA Materials Sciences Division Lawrence Berkeley National Laboratory Berkeley CA USA Department of Materials Science and Engineering Pennsylvania State University State College PA USA Department of Materials Science and Engineering University of California Berkeley CA USA School of Electrical Engineering and Computer Science UC Berkeley Berkeley California USA.

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Emergence of the First Strains of SARS-CoV-2 Lineage B.1.1.7 in Romania: Genomic Analysis

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JMIRx med 2021年第3期2卷 e28049页

作者： Andrei Lobiuc Mihai Dimian Olga Sturdza Roxana Filip Mihai Covasa Department of Human Health and Development College of Physical Exercise and Sport Stefan cel Mare University of Suceava Suceava Romania. Department of Computers Electronics and Automation College of Electrical Engineering and Computer Science Stefan cel Mare University of Suceava Suceava Romania. Integrated Center for Research Development and Innovation in Advanced Materials Nanotechnologies and Distributed Systems for Fabrication and Control Stefan cel Mare University of Suceava Suceava Romania. Suceava County Emergency Hospital Suceava Romania.

BACKGROUND:The United Kingdom reported the emergence of a new and highly transmissible SARS-CoV-2 variant (B.1.1.7) that rapidly spread to other countries. The impact of this new mutation-which occurs in the S protein-on infectivity, virulence, and current vaccine effectiveness is still under evaluation. OBJECTIVE:The aim of this study is to sequence SARS-CoV-2 samples of cases in Romania to detect the B.1.1.7 variant and compare these samples with sequences submitted to GISAID. METHODS:SARS-CoV-2 samples were sequenced and amino acid substitution analysis was performed using the CoV-GLUE platform. RESULTS:We have identified the first cases of the B.1.1.7 variant in samples collected from Romanian patients, of which one was traced to the region of the United Kingdom where the new variant was originally sequenced. Mutations in nonstructural protein 3 (Nsp3; N844S and D455N) and ORF3a (L15F) were also detected, indicating common ancestry with UK strains as well as remote connections with strains from Nagasaki, Japan. CONCLUSIONS:These results indicate, for the first time, the presence and characteristics of the new variant B.1.1.7 in Romania and underscore the need for increased genomic sequencing in patients with confirmed COVID-19.

关键词： COVID-19 Romania case study epidemiology genetics genome impact infectious disease lineage mutation sequencing spread strain transmission variant virology virus

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Spontaneous Magnetic Superdomain Wall Fluctuations in an Artificial Antiferromagnet

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Physical Review Letters 2019年第19期123卷 197202-197202页

作者： X. M. Chen B. Farmer J. S. Woods S. Dhuey W. Hu C. Mazzoli S. B. Wilkins R. V. Chopdekar A. Scholl I. K. Robinson L. E. De Long S. Roy J. T. Hastings Advanced Light Source Lawrence Berkeley National Laboratory Berkeley California 94720 USA Department of Electrical and Computer Engineering University of Kentucky Lexington Kentucky 40506 USA Department of Physics and Astronomy University of Kentucky Lexington Kentucky 40506 USA Materials Science Division Argonne National Laboratory Lemont Illinois 60439 USA Molecular Foundry Lawrence Berkeley National Laboratory Berkeley California 94720 USA National Synchrotron Light Source II Brookhaven National Laboratory Upton New York 11973 USA Condensed Matter Physics and Materials Science Department Brookhaven National Laboratory Upton New York 11973 USA London Centre for Nanotechnology University College Gower Street London WC1E 6BT United Kingdom

Collective dynamics often play an important role in determining the stability of ground states for both naturally occurring materials and metamaterials. We studied the temperature dependent dynamics of antiferromagnetically ordered superdomains in a square artificial spin lattice using soft x-ray photon correlation spectroscopy. We observed an exponential slowing down of superdomain wall motion below the antiferromagnetic onset temperature, similar to the behavior of typical bulk antiferromagnets. Using a continuous time random walk model we show that these superdomain walls undergo low-temperature ballistic and high-temperature diffusive motions.

关键词： Antiferromagnetism Dipolar interaction Domain walls Dynamics of phase separation Magnetic phase transitions Magnetization dynamics

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Multimodal laser micromachined shadow masks for rapid patterning of sub-5 μm organic and inorganic layers for lab-on-a-chip applications 22

Multimodal laser micromachined shadow masks for rapid patter...

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22nd International Conference on Miniaturized Systems for Chemistry and Life sciences, MicroTAS 2018

作者： Hart, Cacie Rajaraman, Swaminathan NanoScience Technology Center University of Central Florida OrlandoFL32816 United States Department of Materials Science and Engineering University of Central Florida OrlandoFL32816 United States Department of Electrical and Computer Engineering University of Central Florida OrlandoFL32816 United States BRIDG - Bridging the Innovation and Development Gap University of Central Florida OrlandoFL32816 United States

ISBN: (纸本)9781510897571

We present a makerspace microfabrication-enabled shadow mask technology utilizing a multimodal Nd:YAG laser with the capability to switch between 1064 nm, 532 nm, and 355 nm wavelengths. This laser allows for the micromachining of a variety of materials from silicon to glass to polymers to metals to biomaterials. With such a laser, we report for the first time to our knowledge, metal and polymer shadow masks for rapid prototyping and robust design to device translation for feature sizes in the sub-5 μm range. In fact, our recent results demonstrate repeatable shadow mask features down to approximately 1.5 μm on Kapton® substrates. Additionally, the demonstration of robust and repeatable patterning of organic and inorganic layers is performed with these masks. We anticipate such a technology will be vital for Lab-on-a-Chip, biosensor, environmental microsensors, and other microfluidic applications. Copyright© (2018) by Chemical and Biological Microsystems *** rights reserved.

关键词： Yttrium aluminum garnet

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Generative Adversarial Networks Enable Cross-Modality Super-Resolution in Fluorescence Microscopy

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Microscopy and Microanalysis 2019年第S2期25卷 1228-1229页

作者： Hongda Wang Yair Rivenson Yiyin Jin Zhensong Wei Ronald Gao Harun Günaydın Laurent A. Bentolila Comert Kural Aydogan Ozcan Electrical & Computer Engineering Department University of California Los Angeles Los Angeles USA Bioengineering Department University of California Los Angeles Los Angeles USA California NanoSystems Institute University of California Los Angeles Los Angeles USA Computer Science Department University of California Los Angeles Los Angeles USA Department of Chemistry and Biochemistry University of California Los Angeles Los Angeles USA Department of Physics Ohio State University Columbus USA Biophysics Graduate Program Ohio State University Columbus USA Department of Surgery David Geffen School of Medicine University of California Los Angeles Los Angeles USA.

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Correction to: Double Vision Model Using Space-Time Function Control within Silicon Microring System

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Silicon 2020年第12期12卷 3057-3057页

作者： Bunruangses, M. Youplao, P. Amiri, I. S. Pornsuwancharoen, N. Yupapin, P. Department of Computer Engineering Faculty of Industrial Education Rajamangala University of Technology Phra Nakhon Bangkok Thailand Department of Electrical Engineering Faculty of Industry and Technology Rajamangala University of Technology Isan Sakon Nakhon Thailand Division of Materials Science and Engineering Boston University Boston USA Computational Optics Research Group Advanced Institute of Materials Science Ton Duc Thang University Ho Chi Minh City Vietnam Faculty of Applied Sciences Ton Duc Thang University Ho Chi Minh City Vietnam

The original version of this article unfortunately contained a mistake in the “Acknowledgments” section.

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Impact of thermal fluctuations on transport in antiferromagnetic semimetals

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Physical Review B 2018年第2期98卷 024409-024409页

作者： Youngseok Kim Moon Jip Park David G. Cahill Matthew J. Gilbert Department of Electrical and Computer Engineering University of Illinois at Urbana-Champaign Urbana Illinois 61801 USA Micro and Nanotechnology Laboratory University of Illinois 208 N. Wright Street Urbana Illinois 61801 USA Department of Physics University of Illinois at Urbana-Champaign Urbana Illinois 61801 USA Department of Materials Science and Engineering and Materials Research Laboratory University of Illinois Urbana Illinois 61801 USA Department of Electrical Engineering Stanford University Stanford California 94305 USA

Recent demonstrations on manipulating antiferromagnetic (AF) order have triggered a growing interest in antiferromagnetic metal, and potential high-density spintronic applications demand further improvements in the anisotropic magnetoresistance (AMR). The antiferromagnetic semimetals (AFS) are newly discovered materials that possess massless Dirac fermions that are protected by the crystalline symmetries. In this material, a reorientation of the AF order may break the underlying symmetries and induce a finite energy gap. As such, the possible phase transition from the semimetallic to insulating phase gives us a choice for a wide range of resistance, ensuring a large AMR. To further understand the robustness of the phase transition, we study thermal fluctuations of the AF order in AFS at a finite temperature. For macroscopic samples, we find that the thermal fluctuations effectively decrease the magnitude of the AF order by renormalizing the effective Hamiltonian. Our finding suggests that the insulating phase exhibits a gap narrowing at elevated temperatures, which leads to a substantial decrease in AMR. We also examine spatially correlated thermal fluctuations for microscopic samples by solving the microscopic Landau-Lifshitz-Gilbert equation, finding a quantitative difference in the gap narrowing effect from that of the macroscopic sample. For both cases, the semimetallic phase shows a minimal change in its transmission spectrum, illustrating the robustness of the symmetry-protected states in AFS. Our finding may serve as a guideline for estimating and maximizing AMR of the AFS samples at elevated temperatures.

关键词： Antiferromagnetism Dirac fermions Magnetoresistance Metal-insulator transition Dirac semimetal Green's function methods Landau-Lifschitz-Gilbert equation

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A metasurface-inspired focusing collector for concentrated solar power applications

A metasurface-inspired focusing collector for concentrated s...

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Frontiers in Optics, FIO 2018

作者： Ding, Qing Barna, Shama Jacobs, Kyle Choubal, Aakash Mensing, Glennys Zhang, Zhong Yamada, Kaito Tirawat, Robert Kincaid, Nicholas Zhu, Guangdong Wendelin, Tim Guo, L. Jay Ferreira, Placid Toussaint, Kimani C. University of Illinois at Urbana-Champaign UrbanaIL61801 United States Department of Electrical and Computer Engineering University of Illinois at Urbana-Champaign UrbanaIL61801 United States Department of Mechanical Science and Engineering University of Illinois at Urbana-Champaign UrbanaIL61801 United States Department of Electrical Engineering and Computer Science University of Michigan Ann ArborMI48109-2102 United States Applied Physics Program University of Michigan Ann ArborMI48109 United States National Renewable Energy Lab. GoldenCO80401 United States Solar Dynamics LLC United States Department of Bioengineering University of Illinois at Urbana-Champaign UrbanaIL61801 United States

We present a simple metasurface-inspired planar focusing collector for concentrated solar power. Fabrication is achieved using two-photon lithography, and subsequent nanoimprint lithography tests for scalability. Opti... 详细信息

ISBN: (纸本)9781943580460

关键词： Solar energy

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