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Controlled synthetic chirality in macroscopic assemblies of carbon nanotubes

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arXiv 2023年

作者： Doumani, Jacques Lou, Minhan Dewey, Oliver Hong, Nina Fan, Jichao Baydin, Andrey Yomogida, Yohei Yanagi, Kazuhiro Pasquali, Matteo Saito, Riichiro Kono, Junichiro Gao, Weilu Department of Electrical and Computer Engineering Rice University HoustonTX United States Applied Physics Graduate Program Smalley–Curl Institute Rice University HoustonTX United States Department of Electrical and Computer Engineering The University of Utah Salt Lake CityUT United States Carbon Hub Rice University HoustonTX United States Department of Chemical and Biomolecular Engineering Rice University HoustonTX United States J.A. Woollam Co. Inc. LincolnNE United States Smalley–Curl Institute Rice University HoustonTX United States Department of Physics Tokyo Metropolitan University Tokyo Japan Department of Chemistry Rice University HoustonTX United States Department of Materials Science and NanoEngineering Rice University HoustonTX United States Department of Physics Tohoku University Sendai Japan Department Physics and Astronomy Rice University HoustonTX United States

There is an emerging recognition that successful utilization of chiral degrees of freedom can bring new scientific and technological opportunities to diverse research areas. Hence, methods are being sought for creating artificial matter with controllable chirality in an uncomplicated and reproducible manner. Here, we report the development of two straightforward methods for fabricating wafer-scale chiral architectures of ordered carbon nanotubes (CNTs) with tunable and giant circular dichroism (CD). Both methods employ simple approaches, (i) mechanical rotation and (ii) twist-stacking, based on controlled vacuum filtration and do not involve any sophisticated nanofabrication processes. We used a racemic mixture of CNTs as the starting material, so the intrinsic chirality of chiral CNTs is not responsible for the observed chirality. In particular, by controlling the stacking angle and handedness in (ii), we were able to maximize the CD response and achieve a record-high deep-ultraviolet ellipticity of 40 ± 1 mdeg/nm. Our theoretical simulations using the transfer matrix method reproduce the salient features of the experimentally observed CD spectra and further predict that a film of twist-stacked CNTs with an optimized thickness will exhibit an ellipticity as high as 150 mdeg/nm. The created wafer-scale objects represent a new class of synthetic chiral matter consisting of ordered quantum wires whose macroscopic properties are governed by nanoscopic electronic signatures such as van Hove singularities. These artificial structures with engineered chirality will not only provide playgrounds for uncovering new chiral phenomena but also open up new opportunities for developing high-performance chiral photonic and optoelectronic devices. © 2023, CC BY.

关键词： Carbon nanotubes

Ferroelectric Nematic and Smectic Liquid Crystals with Sub-Molecular Spatial Correlations

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arXiv 2025年

作者： Guragain, Parikshit Ghimire, Arjun Badu, Manisha Dhakal, Netra Prasad Nepal, Pawan Gleeson, James T. Sprunt, Samuel Twieg, Robert J. Jákli, Antal Department of Chemistry and Biochemistry Kent State University KentOH44242 United States Department of Physics Kent State University KentOH44242 United States Materials Science Graduate Program and Advanced Materials Liquid Crystal Institute Kent State University KentOH44242 United States

A number of highly polar three ring rod-shaped compounds with a terminal thiophene ring have been synthesized and the physical properties of a subset are reported in detail. On cooling from the isotropic fluid, they directly transition to a ferroelectric nematic liquid crystal (NF) phase that shows the strongest spatial correlations corresponding to 1/3 of the molecular length (L/3). The set of thiophene compounds reported here have ferroelectric polarizations of P! ≈ 7.8 ± 0.3 µC/cm", which is about 20% larger than that of usual ferroelectric nematic liquid crystal materials. Such large polarization values are due to the ~20% larger mass densities of these thiophene compounds compared to most of the NF materials with short terminal chains. These unusual properties are consequences of tighter molecular packing due to the lack of flexible terminal chains. Below the NF phase, compounds with a single nitro or two cyano polar groups on the terminal benzene ring exhibit a so far never observed smectic phase with periodicity ~1/3 the molecular length. Based on our experimental results, we propose a model of this phase featuring antipolar packing of the molecules within the layers. © 2025, CC BY-NC-ND.

关键词： Nematic liquid crystals

Chiral quasi-bound states in the continuum

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arXiv 2020年

作者： Overvig, Adam Yu, Nanfang Alù, Andrea Photonics Initiative Advanced Science Research Center The Graduate Center The City University of New York United States Department of Applied Physics and Applied Mathematics Columbia University United States Physics Program Graduate Center City University of New York United States

Quasi-bound states in the continuum (q-BICs) are resonant states of suitably tailored nanostructures with long optical lifetimes controlled by symmetry-breaking perturbations. While in planarized ultrathin devices the resulting Fano resonance is limited to linear polarization, we show here that chiral perturbations extend q-BIC concepts to arbitrary elliptical polarizations. Using geometric phase engineering, we realize metasurfaces with ultrasharp Fano spectral features that can shape the impinging wavefront with near-unity efficiency, while at the same time precisely filtering their spectral content. Copyright © 2020, The Authors. All rights reserved.

关键词： Polarization

Surface-wave propagation on non-Hermitian Metasurfaces with extreme anisotropy

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arXiv 2021年

作者： Coppolaro, Marino Moccia, Massimo Castaldi, Giuseppe Alù, Andrea Galdi, Vincenzo The Fields & Waves Lab Department of Engineering University of Sannio Ben-eventoI-82100 Italy The Photonics Initiative Advanced Science Research Center The Physics Program Graduate Center The Department of Electrical Engineering City College The City University of New York New YorkNY10031 United States

Electromagnetic metasurfaces enable the advanced control of surface-wave propagation by spatially tailoring the local surface reactance. Interestingly, tailoring the surface resistance distribution in space provides new, largely unexplored degrees of freedom. Here, we show that suitable spatial modulations of the surface resistance between positive (i.e., loss) and negative (i.e., gain) values can induce peculiar dispersion effects, far beyond a mere compensation. Taking inspiration from the parity-time symmetry concept in quantum physics, we put forward and explore a class of non-Hermitian metasurfaces that may exhibit extreme anisotropy mainly induced by the gain-loss interplay. Via analytical modeling and full-wave numerical simulations, we illustrate the associated phenomenon of surface-wave canalization, explore nonlocal effects and possible departures from the ideal conditions, and address the feasibility of the required constitutive parameters. Our results suggest intriguing possibilities to dynamically reconfigure the surface-wave propagation, and are of potential interest for applications to imaging, sensing and communications. © 2021, CC BY.

关键词： Surface waves

Bridging between type IIb and Ib supernovae: SN IIb 2022crv with a very thin Hydrogen envelope

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arXiv 2023年

作者： Gangopadhyay, Anjasha Maeda, Keiichi Singh, Avinash Nayana, A.J. Nakaoka, Tatsuya Kawabata, Koji S. Taguchi, Kenta Singh, Mridweeka Chandra, Poonam Ryder, Stuart D. Dastidar, Raya Yamanaka, Masayuki Kawabata, Miho Alsaberi, Rami Z.E. Dukiya, Naveen Teja, Rishabh Singh Ailawadhi, Bhavya Dutta, Anirban Sahu, D.K. Moriya, Takashi J. Misra, Kuntal Tanaka, Masaomi Chevalier, Roger Tominaga, Nozomu Uno, Kohki Imazawa, Ryo Hamada, Taisei Hori, Tomoya Isogai, Keisuke Hiroshima Astrophysical Science Centre Hiroshima University 1-3-1 Kagamiyama Higashi-Hiroshima Hiroshima739-8526 Japan Department of Astronomy Kyoto University Kitashirakawa-Oiwake-cho Sakyo-ku Kyoto606-8502 Japan Indian Institute of Astrophysics Koramangala 2nd Block Bangalore560034 India Department of Physics Graduate School of Advanced Science and Engineering Hiroshima University 1-3-1 Kagamiyama Higashi-Hiroshima Hiroshima739-8526 Japan National Radio Astronomy Observatory 520 Edgemont Road CharlottesvilleVA22903 United States School of Mathematical and Physical Sciences Macquarie University NSW2109 Australia Astrophysics and Space Technologies Research Centre Macquarie University SydneyNSW2109 Australia Instituto de Astrofísica Universidad Andres Bello Fernandez Concha 700 Las Condes RM Santiago Chile Millennium Institute of Astrophysics Nuncio Monsenor Sótero Sanz 100 Providencia Santiago8320000 Chile Graduate School of Science and Engineering Kagoshima University 1-21-35 Korimoto Kagoshima Kagoshima890-0065 Japan Nishi-Harima Astronomical Observatory Center for Astronomy University of Hyogo 407-2 Nishigaichi Sayo-cho Hyogo Sayo679-5313 Japan Western Sydney University Locked Bag 1797 PenrithNSW2751 Australia Aryabhatta Research Institute of observational sciencES Manora Peak Nainital263 002 India Department of Applied Physics Mahatma Jyotiba Phule Rohilkhand University Bareilly243006 India Pondicherry University Chinna Kalapet Puducherry Kalapet605014 India Department of Physics Deen Dayal Upadhyaya Gorakhpur University Gorakhpur273009 India National Astronomical Observatory of Japan National Institutes of Natural Sciences 2-21-1 Osawa Mitaka Tokyo181-8588 Japan School of Physics and Astronomy Faculty of Science Monash University ClaytonVIC3800 Australia Astronomical Institute Tohoku University Aoba Sendai980-8578 Japan University Of Virginia Astronomy Building 530 McCormick Road CharlottesvilleVA2290

We present optical, near-infrared, and radio observations of supernova (SN) SN IIb 2022crv. We show that it retained a very thin H envelope and transitioned from a SN IIb to a SN Ib;prominent Hα seen in the pre-maximum phase diminishes toward the post-maximum phase, while He i lines show increasing strength. SYNAPPS modeling of the early spectra of SN 2022crv suggests that the absorption feature at 6200 Å is explained by a substantial contribution of Hα together with Si ii, as is also supported by the velocity evolution of Hα. The light-curve evolution is consistent with the canonical stripped-envelope supernova subclass but among the slowest. The light curve lacks the initial cooling phase and shows a bright main peak (peak MV =−17.82±0.17 mag), mostly driven by radioactive decay of 56Ni. The light-curve analysis suggests a thin outer H envelope (Menv ∼0.05 M☉) and a compact progenitor (Renv ∼3 R☉). An interaction-powered synchrotron self-absorption (SSA) model can reproduce the radio light curves with a mean shock velocity of 0.1c. The mass-loss rate is estimated to be in the range of (1.9−2.8) × 10−5 M☉ yr−1 for an assumed wind velocity of 1000 km s−1, which is on the high end in comparison with other compact SNe IIb/Ib. SN 2022crv fills a previously unoccupied parameter space of a very compact progenitor, representing a beautiful continuity between the compact and extended progenitor scenario of SNe IIb/Ib. Copyright © 2023, The Authors. All rights reserved.

关键词： Supernovae

Temporal signal processing with nonlocal optical metasurfaces

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npj Nanophotonics

npj Nanophotonics 2024年第1期1卷 1-9页

作者： Michele Cotrufo Sedigheh Esfahani Dmitriy Korobkin Andrea Alù Photonics Initiative Advanced Science Research Center City University of New York New York NY 10031 USA The Institute of Optics University of Rochester Rochester NY 14627 USA Physics Program Graduate Center of the City University of New York New York NY 10016 USA

Nonlocal metasurfaces have recently enabled an ultra-compact, low-power and high-speed platform to perform analog image processing. While several computational tasks have been demonstrated based on this platform, most of the previous studies have focused only on spatial operations, such as spatial differentiation and edge detection. Here, we demonstrate that metasurfaces with temporal nonlocalities – that is, with a tailored dispersive response – can be used to implement time-domain signal processing in deeply subwavelength footprints. In particular, we experimentally demonstrate a passive metasurface performing first-order differentiation of input signals with high-fidelity and high-efficiency. We also show that this approach is prone to scalability and cascaded computation. Our work paves the way to a new generation of ultra-compact, passive devices for all-optical computation, with applications in neural networks and neuromorphic computing.

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Low-Velocity-Favored Transition Radiation

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Physical Review Letters 2023年第11期131卷 113002-113002页

作者： Jialin Chen Ruoxi Chen Fuyang Tay Zheng Gong Hao Hu Yi Yang Xinyan Zhang Chan Wang Ido Kaminer Hongsheng Chen Baile Zhang Xiao Lin Interdisciplinary Center for Quantum Information State Key Laboratory of Extreme Photonics and Instrumentation ZJU-Hangzhou Global Scientific and Technological Innovation Center College of Information Science & Electronic Engineering Zhejiang University Hangzhou 310027 China International Joint Innovation Center the Electromagnetics Academy at Zhejiang University Zhejiang University Haining 314400 China Department of Electrical and Computer Engineering Technion-Israel Institute of Technology Haifa 32000 Israel Department of Electrical and Computer Engineering Rice University Houston Texas 77005 USA Applied Physics Graduate Program Smalley-Curl Institute Rice University Houston Texas 77005 USA School of Electrical and Electronic Engineering Nanyang Technological University Singapore 639798 Singapore Department of Physics University of Hong Kong Hong Kong 999077 China Key Lab of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang Jinhua Institute of Zhejiang University Zhejiang University Jinhua 321099 China Shaoxing Institute of Zhejiang University Zhejiang University Shaoxing 312000 China Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University Singapore 637371 Singapore Centre for Disruptive Photonic Technologies Nanyang Technological University Singapore 637371 Singapore

When a charged particle penetrates through an optical interface, photon emissions emerge—a phenomenon known as transition radiation. Being paramount to fundamental physics, transition radiation has enabled many applications from high-energy particle identification to novel light sources. A rule of thumb in transition radiation is that the radiation intensity generally decreases with the decrease of particle velocity v; as a result, low-energy particles are not favored in practice. Here, we find that there exist situations where transition radiation from particles with extremely low velocities (e.g., v/c<10−3) exhibits comparable intensity as that from high-energy particles (e.g., v/c=0.999), where c is the light speed in free space. The comparable radiation intensity implies an extremely high photon extraction efficiency from low-energy particles, up to 8 orders of magnitude larger than that from high-energy particles. This exotic phenomenon of low-velocity-favored transition radiation originates from the interference of the excited Ferrell-Berreman modes in an ultrathin epsilon-near-zero slab. Our findings may provide a promising route toward the design of integrated light sources based on low-energy electrons and specialized detectors for beyond-standard-model particles.

关键词： Atom or molecule scattering from surfaces Atomic & molecular collisions Cherenkov radiation Crystal optics Electron beams & optics Light-matter interaction Optical sources & detectors Optical transient phenomena Plasmonics

Interaction-driven transport of dark excitons in 2D semiconductors with phonon-mediated optical readout

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arXiv 2022年

作者： Chand, Saroj B. Woods, John M. Quan, Jiamin Mejia, Enrique Taniguchi, Takashi Watanabe, Kenji Alù, Andrea Grosso, Gabriele Photonics Initiative Advanced Science Research Center City University of New York New YorkNY10031 United States International Center for Materials Nanoarchitectonics National Institute for Materials Science 1-1 Namiki Tsukuba305-0044 Japan Research Center for Functional Materials National Institute for Materials Science 1-1 Namiki Tsukuba305-0044 Japan Department of Electrical Engineering City College of the City University of New York New YorkNY10031 United States Physics Program Graduate Center City University of New York New YorkNY10016 United States

The growing field of quantum information technology requires propagation of information over long distances with efficient readout mechanisms. Excitonic quantum fluids have emerged as a powerful platform for this task due to their straightforward electro-optical conversion. In two-dimensional transition metal dichalcogenides, the coupling between spin and valley provides exciting opportunities for harnessing, manipulating and storing bits of information. However, the large inhomogeneity of single layers cannot be overcome by the properties of bright excitons, hindering spin-valley transport. Nonetheless, the rich band structure supports dark excitonic states with strong binding energy and longer lifetime, ideally suited for long-range transport. Here we show that dark excitons can diffuse over several micrometers and prove that this repulsion-driven propagation is robust across non-uniform samples. The long-range propagation of dark states with an optical readout mediated by chiral phonons provides a new concept of excitonic devices for applications in both classical and quantum information technology. Copyright © 2022, The Authors. All rights reserved.

关键词： Sulfur compounds

Single to multiple acoustic vortex excitations in the transition to defect-mediated dust acoustic wave turbulence

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Physical Review E 2020年第2期101卷 023210-023210页

作者： Jun-Yi Tsai Po-Cheng Lin Lin I Department of Physics and Center for Complex Systems National Central University Jhongli Taiwan 32001 Republic of China Molecular Science and Technology Taiwan International Graduate Program Academia Sinica and National Central University Taipei Taiwan 10617 Republic of China

We experimentally investigate the cooperative excitations in the transition from a self-excited three-dimensional ordered plane wave to a defect-mediated turbulence (DMT) state with multiple unstable defect filaments in a dusty plasma system. It is found that, with increasing effective driving, a single acoustic vortex (AV) with positive or negative helicity winding around a long straight defect filament with small wiggling in the 2+1D (dimensional) space-time space starts to emerge along the center axis of the small dust cluster. The sequential ruptures of the crest surfaces from the cluster boundary followed by their reconnection with adjacent ruptured crest surfaces, or repelling one of the pairwise generated defects out of the boundary, are the key for the single AV generation. Further increasing driving makes the single defect filament exhibit helical excursion in the 2+1D space. The system eventually enters the state with a few short-lived AVs and the DMT state with multiple AVs. The gradual increasing defect filament fluctuations and defect number in the transition to the DMT more strongly distort the nearby waveforms, which leads to the transition from the emergence of distinct sideband peaks to the broadened peaks in the power spectra of temporal dust density fluctuation. For the system with a larger cluster size, the single AV states are skipped in the transition to the DMT state.

关键词： Defects Plasma turbulence Plasma waves Topological defects Transition to turbulence Collective dynamics Dusty or complex plasma Nonlinear waves