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Riemann-Encircling Exceptional Points for Efficient Asymmetric Polarization-Locked Devices

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Physical Review Letters 2022年第12期129卷 127401-127401页

作者： Aodong Li Weijin Chen Heng Wei Guowei Lu Andrea Alù Cheng-Wei Qiu Lin Chen Wuhan National Laboratory for Optoelectronics and School of Optical and Electronic Information Huazhong University of Science and Technology Wuhan 430074 China Department of Electrical and Computer Engineering National University of Singapore Singapore 117583 Singapore State Key Laboratory for Mesoscopic Physics School of Physics Peking University Beijing 100871 China Photonics Initiative Advanced Science Research Center City University of New York New York New York 10031 USA Physics Program Graduate Center City University of New York New York New York 10016 USA

Dynamically encircling exceptional points (EPs) have unveiled intriguing chiral dynamics in photonics. However, the traditional approach based on an open manifold of Hamiltonian parameter space fails to explore trajectories that pass through an infinite boundary. Here, by mapping the full parameter space onto a closed manifold of the Riemann sphere, we introduce a framework to describe encircling-EP loops. We demonstrate that an encircling trajectory crossing the north vertex can realize near-unity asymmetric transmission. An efficient gain-free, broadband asymmetric polarization-locked device is realized by mapping the encircling path onto L-shaped silicon waveguides.

关键词： PT-symmetric quantum mechanics Photonics

Topological transformations of a nematic drop

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arXiv 2023年

作者： Koizumi, Runa Golovaty, Dmitry Alqarni, Ali Li, Bing-Xiang Sternberg, Peter J. Lavrentovich, Oleg D. Advanced Materials and Liquid Crystal Institute Materials Science Graduate Program Kent State University KentOH44242 United States Department of Mathematics The University of Akron AkronOH44325-4002 United States College of Electronics and Optical Engineering College of Microelectronics Nanjing University of Posts and Telecommunications Nanjing210023 China Department of Mathematics Indiana University BloomingtonIN47405 United States Department of Physics Kent State University KentOH44242 United States

Morphogenesis of living systems involves topological shape transformations which are highly unusual in the inanimate world. Here we demonstrate that a droplet of a nematic liquid crystal changes its equilibrium shape from a simply-connected tactoid, which is topologically equivalent to a sphere, to a torus, which is not simply-connected. The topological shape transformation is caused by the interplay of nematic elastic constants, which facilitates splay and bend of molecular orientations in tactoids but hinders splay in the toroids. The elastic anisotropy mechanism might be helpful in understanding topology transformations in morphogenesis and paves the way to control and transform shapes of droplets of liquid crystals and related soft materials. © 2023, CC BY.

关键词： Drops

Utilizing probabilistic entanglement between sensors in quantum networks

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arXiv 2024年

作者： Van Milligen, Emily A. Gagatsos, Christos N. Kaur, Eneet Towsley, Don Guha, Saikat Department of Physics The University of Arizona 1630 East University Boulevard TucsonAZ85721 United States Department of Electrical and Computer Engineering The University of Arizona 1630 East University Boulevard TucsonAZ85721 United States Wyant College of Optical Sciences The University of Arizona 1630 East University Boulevard TucsonAZ85721 United States Program in Applied Mathematics The University of Arizona TucsonAZ85721 United States Cisco Quantum Lab Los Angeles United States College of Computer Science University of Massachusetts AmherstMA United States

One of the most promising applications of quantum networks is entanglement assisted sensing. The field of quantum metrology exploits quantum correlations to improve the precision bound for applications such as precision timekeeping, field sensing, and biological imaging. When measuring multiple spatially distributed parameters, current literature focuses on quantum entanglement in the discrete variable case—and quantum squeezing in the continuous variable case distributed amongst all of the sensors in a given network. However, it can be difficult to ensure all sensors pre-share entanglement of sufficiently high fidelity. This work probes the space between fully entangled and fully classical sensing networks by modeling a star network with probabilistic entanglement generation that is attempting to estimate the average of local parameters. The quantum Fisher information is used to determine which protocols best utilize entanglement as a resource for different network conditions. It is shown that without entanglement distillation there is a threshold fidelity below which classical sensing is preferable. For a network with a given number of sensors and links characterized by a certain initial fidelity and probability of success, this work outlines when and how to use entanglement, when to store it, and when it needs to be distilled. © 2024, CC BY.

关键词： Quantum entanglement

Hyperchromatic Structural Color for Perceptually Enhanced Colorimetric Sensing by the Naked Eye

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Hyperchromatic Structural Color for Perceptually Enhanced Co...

Conference on Lasers and Electro-Optics (CLEO)

作者： Tahmid H. Talukdar Bria McCoy Sarah Κ Timmins Taufiquar Khan Judson D. Ryckman Clemson University Clemson South Carolina Charles H. Townes Optical Science and Engineering Summer Program Clemson University Clemson South Carolina USA Clemson University Clemson South Carolina USA University of North Carolina Charlotte NC

We report a novel colorimetric sensing paradigm using multi-chromatic light from an RGB laser combined with a structural color sensor for fast, ultra-sensitive, and spatio-temporally resolved detection of surface biom... 详细信息

关键词： Surface emitting lasers Color Molecular biophysics Sensors Electrooptical waveguides

In situ Light-Writable Orientation Control in Liquid Crystal Elastomer Film Enabled by Chalcones

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Angewandte Chemie 2024年第11期136卷

作者： Yiyi Xu Xinfang Zhang Zhenpeng Song Xiao Chen Yinliang Huang Jinyu Wang Prof. Bingxiang Li Prof. Shuai Huang Prof. Quan Li Institute of Advanced Materials and School of Chemistry and Chemical Engineering Southeast University Nanjing 211189 China Materials Science Graduate Program Kent State University Kent OH-44242 USA College of Electronic and Optical Engineering & College of Flexible Electronics (Future Technology) Nanjing University of Posts and Telecommunications Nanjing 210023 China

Liquid crystal elastomers (LCEs) are stimulus-responsive materials with intrinsic anisotropy. However, it is still challenging to in situ program the mesogen alignment to realize three-dimensional (3D) deformations with high-resolution patterned structures. This work presents a feasible strategy to program the anisotropy of LCEs by using chalcone mesogens that can undergo a photoinduced cycloaddition reaction under linear polarized light. It is shown that by controlling the polarization director and the irradiation region, patterned alignment distribution in a freestanding LCE film can be created, which leads to complex and reversible 3D shape-morphing behaviors. The work demonstrates an in situ light-writing method to achieve sophisticated topography changes in LCEs, which has potential applications in encryption, sensors, and beyond.

关键词： Chalcone-Based Liquid Crystal Liquid Crystal Elastomer Photo-Crosslinked Material Polarized Light Alignment

Low-Temperature Synthesis of Weakly Confined Carbyne inside Single-Walled Carbon Nanotubes

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arXiv 2024年

作者： Zhang, Bo-Wen Qiu, Xi-Yang Ma, Yicheng Hu, Qingmei Fitó-Parera, Aina Kohata, Ikuma Feng, Ya Zheng, Yongjia Zhang, Chiyu Matsuo, Yutaka Wang, YuHuang Chiashi, Shohei Otsuka, Keigo Xiang, Rong Levshov, Dmitry I. Cambré, Sofie Wenseleers, Wim Rotkin, Slava V. Maruyama, Shigeo Department of Mechanical Engineering The University of Tokyo Tokyo113-8656 Japan State Key Laboratory of Fluid Power and Mechatronic Systems School of Mechanical Engineering Zhejiang University Hangzhou310027 China Theory and Spectroscopy of Molecules and Materials Department of Physics University of Antwerp Antwerp2610 Belgium Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education School of Energy and Power Engineering Dalian University of Technology Liaoning 116024 China Department of Chemistry and Biochemistry Chemical Physics Program Maryland Nano Center University of Maryland College ParkMD20742 United States Department of Chemical Systems Engineering Graduate School of Engineering Nagoya University Nagoya464-8603 Japan Institute of Materials Innovation Institutes for Future Society Nagoya University Nagoya464-8603 Japan Theory and Spectroscopy of Molecules and Materials Department of Chemistry University of Antwerp Antwerp2610 Belgium Nanostructured and Organic Optical and Electronic Materials Department of Physics University of Antwerp Antwerp2610 Belgium Materials Research Institute Department of Engineering Science & Mechanics The Pennsylvania State University University ParkPA16802 United States

Carbyne, a one-dimensional (1D) carbon allotrope with alternating triple and single bonds, has the highest known mechanical strength but is unstable to bending, limiting synthesis to short linear chains. Encapsulation within carbon nanotubes (CNTs) stabilizes carbyne, forming confined carbyne (CC), thus enabling further research concerning attractive 1D physics and materials properties of carbyne. While CC has been synthesized in multi-walled CNTs (MWCNTs) using the arc-discharge method and in double-walled CNTs (DWCNTs) via high-temperature high-vacuum (HTHV) method, synthesis in single-walled CNTs (SWCNTs) has been challenging due to their fragility under such conditions. In this work, we report a low-temperature method to synthesize CC inside SWCNTs (CC@SWCNT). By annealing SWCNTs containing ammonium deoxycholate (ADC) at 400°C, ADC is converted into CC without damaging the SWCNTs. Raman spectroscopy revealed a strong CC phonon (CC-mode) peak at 1860–1870 cm-1, much stronger than the SWCNT G-band peak, confirming a high fraction of CC in the resulting material. The Raman mapping result showed the uniformity of the CC-mode signal across the entire film sample, proving the high efficiency of this method in synthesizing CC in every SWCNT of appropriate size. Notably, the CC-mode peaks of CC@SWCNT (above 1860 cm-1) are higher than those reported in previous CC@CNT samples (mostly -1). This is attributed to larger SWCNT diameters (>0.95 nm) used in this study, compared to the typical 0.6–0.8 nm range. Larger diameters result in reduced confinement, allowing carbyne to closely resemble free-standing carbyne while remaining stabilized. This low-temperature synthesis of long-chain, nearly freestanding carbyne within large-diameter SWCNTs offers new opportunities for exploring 1D physics and the unique properties of carbyne for potential applications. © 2024, CC BY-NC-ND.

关键词： Single-walled carbon nanotubes (SWCN)

Absorption dispersion below boson peak frequency in oxide glasses studied by THz-time domain spectroscopy

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Journal of Applied Physics 2024年第8期135卷

作者： Wada, Osamu Ramachari, Doddoji Yang, Chan-Shan Uchino, Takashi Pan, Ci-Ling Department of Physics National Tsing Hua University Hsinchu30013 Taiwan Office for Academic and Industrial Innovation Kobe University Kobe657-8501 Japan Institute of Research and Development Duy Tan University Da Nang550000 Viet Nam Faculty of Natural Sciences Duy Tan University Da Nang550000 Viet Nam Institute and Undergraduate Program of Electro-Optical Engineering National Taiwan Normal University Taipei11677 Taiwan Micro/Nano Device Inspection and Research Center National Taiwan Normal University Taipei106 Taiwan Graduate School of Science Kobe University Kobe657-8501 Japan

The dispersion properties of the absorption coefficients [α(ν)] of different multi-component silicate oxide glasses have been studied in the frequency region below the boson peak by using THz-time-domain spectroscopy. The value of α(ν)/ν2 has been shown to exhibit a minimum level (R) at low frequency and subsequently a linear increase in the form of r(ν/νBP + E) with increasing frequency, where νBP is the boson peak frequency and R, r, and E are material-specific constants. It has also been found that R ∝ r and E is a constant common to most glasses. This α(ν)/ν2 behavior is ascribed to the dispersion property of the light-vibration coupling coefficient under the reasonable vibrational density of state function. The minimum (constant) and linear terms of the α(ν)/ν2 spectrum are originated from the physical/chemical disorder-induced charge fluctuations in the long-range scale (constant term) and short-range scale (linear term), respectively. The fluctuating charge (σ1) caused by uncorrelated, long-range disorders has primary significance for determining the sub-THz absorption dispersion properties, and its value has been determined for each glass material. © 2024 Author(s).

关键词： Glass

Intrinsic Exciton-Phonon Coupling and Tuning in ZnTe Nanowires Probed by Resonant Raman Scattering

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Physical Review Applied 2020年第1期13卷 011001-011001页

作者： Yingyan Yi Jason K. Marmon Yuanping Chen Fan Zhang Tao Sheng Priyalal S. Wijewarnasuriya Haitao Zhang Yong Zhang Department of Electrical and Computer Engineering University of North Carolina at Charlotte Charlotte North Carolina 28223 USA School of Science Wuhan University of Technology Wuhan Hubei 430070 China Nanoscale Science Graduate Program University of North Carolina at Charlotte Charlotte North Carolina 28223 USA US Army Research Laboratory Adelphi Maryland 20783 USA Optical Science and Engineering Graduate Program University of North Carolina at Charlotte Charlotte North Carolina 28223 USA Department of Mechanical Engineering and Engineering Science University of North Carolina at Charlotte Charlotte North Carolina 28223 USA

We show in ZnTe that the 2LO to 1LO resonant Raman intensity ratio, a measure of electron-phonon coupling (EPC), exhibits a much larger intrinsic value than that previously reported and minimal change from bulk to 30 nm nanowires. However, the ratio can be tuned extrinsically over one order in magnitude controllably either during or after growth, and thus, allows for the programing of EPC or quantum information in nanoscale devices. This work helps to understand a matter of controversy in the literature for more than three decades, regarding the EPC size dependence in nanostructures, and provides unambiguous experimental results for validating EPC theories with reduced dimensionality.

关键词： Crystal defects Electron-phonon coupling Excitons Optoelectronics Nanowires Semiconductor compounds Photoluminescence Raman spectroscopy

Topological electronic crystals in twisted bilayer-trilayer graphene

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arXiv 2024年

作者： Su, Ruiheng Waters, Dacen Zhou, Boran Watanabe, Kenji Taniguchi, Takashi Zhang, Ya-Hui Yankowitz, Matthew Folk, Joshua Quantum Matter Institute University of British Columbia VancouverBCV6T 1Z1 Canada Department of Physics and Astronomy University of British Columbia VancouverBCV6T 1Z1 Canada Department of Physics University of Washington SeattleWA98195 United States Intelligence Community Postdoctoral Research Fellowship Program University of Washington SeattleWA98195 United States Department of Physics and Astronomy Johns Hopkins University BaltimoreMD21205 United States Research Center for Electronic and Optical Materials National Institute for Materials Science 1-1 Namiki Tsukuba305-0044 Japan Research Center for Materials Nanoarchitectonics National Institute for Materials Science 1-1 Namiki Tsukuba305-0044 Japan Department of Materials Science and Engineering University of Washington SeattleWA98195 United States

In a dilute two-dimensional electron gas, Coulomb interactions can stabilize the formation of a Wigner crystal [1-3]. Although Wigner crystals are topologically trivial, it has been predicted that electrons in a partially-filled band can break continuous translational symmetry and time-reversal symmetry spontaneously to form a form of topological electron crystal known as an anomalous Hall crystal [4-11]. Here, we report the observation of a generalized version of the anomalous Hall crystal in twisted bilayer-trilayer graphene, whose formation is driven by the moiré potential. The crystal forms at a band filling factor of one electron per four moiré unit cells (ν = 1/4) and quadruples the unit-cell area, coinciding with an integer quantum anomalous Hall effect. The Chern number of the state is exceptionally tunable, and can be switched reversibly between +1 and -1 by electric and magnetic fields. Several other topological electronic crystals arise in a modest magnetic field, originating from ν = 1/3, 1/2, 2/3, and 3/2. The quantum geometry of the folded bands is likely very different from that of the original parent band, enabling possible future discoveries of correlationdriven topological phenomena. © 2024, CC BY.

关键词： Crystal symmetry