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KamLAND's search for correlated low-energy electron antineutrinos with astrophysical neutrinos from IceCube

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arXiv 2022年

作者： Abe, S. Asami, S. Eizuka, M. Futagi, S. Gando, A. Gando, Y. Gima, T. Goto, A. Hachiya, T. Hata, K. Hosokawa, K. Ichimura, K. Ieki, S. Ikeda, H. Inoue, K. Ishidoshiro, K. Kamei, Y. Kawada, N. Kishimoto, Y. Kinoshita, T. Koga, M. Kurasawa, M. Maemura, N. Mitsui, T. Miyake, H. Nakahata, T. Nakamura, K. Nakamura, K. Nakamura, R. Ozaki, H. Sakai, T. Sambonsugi, H. Shimizu, I. Shirai, J. Shiraishi, K. Suzuki, A. Suzuki, Y. Takeuchi, A. Tamae, K. Watanabe, H. Yoshida, Y. Obara, S. Ichikawa, A.K. Yoshida, S. Umehara, S. Fushimi, K. Kotera, K. Urano, Y. Berger, B.E. Fujikawa, B.K. Learned, J.G. Maricic, J. Axani, Spencer N. Smolsky, J. Lertprasertpong, J. Winslow, L.A. Fu, Z. Ouellet, J. Efremenko, Y. Karwowski, H.J. Markoff, D.M. Tornow, W. Li, A. Detwiler, J.A. Enomoto, S. Decowski, M.P. Grant, C. Song, H. O'Donnell, T. Dell'Oro, S. Research Center for Neutrino Science Tohoku University Sendai980-8578 Japan Frontier Research Institute for Interdisciplinary Sciences Tohoku University Sendai980-8578 Japan Graduate Program on Physics for the Universe Tohoku University Sendai980-8578 Japan Department of Physics Tohoku University Sendai980-8578 Japan Institute for the Physics and Mathematics of the Universe The University of Tokyo Kashiwa277-8568 Japan Graduate School of Science Osaka University Toyonaka560-0043 Japan Osaka University Osaka Ibaraki567-0047 Japan Graduate School of Advanced Technology and Science Tokushima University Tokushima770-8506 Japan Nuclear Science Division Lawrence Berkeley National Laboratory BerkeleyCA94720 United States Department of Physics and Astronomy University of Hawaii at Manoa HonoluluHI96822 United States Massachusetts Institute of Technology CambridgeMA02139 United States Boston University BostonMA02215 United States Department of Physics and Astronomy University of Tennessee KnoxvilleTN37996 United States Triangle Universities Nuclear Laboratory DurhamNC27708 United States The University of North Carolina at Chapel Hill Chapel HillNC27599 United States North Carolina Central University DurhamNC27701 United States Physics Department Duke University DurhamNC27705 United States Center for Experimental Nuclear Physics and Astrophysics University of Washington SeattleWA98195 United States Nikhef The University of Amsterdam Science Park Amsterdam Netherlands Center for Neutrino Physics Virginia Polytechnic Institute State University BlacksburgVA24061 United States

We report the results of a search for MeV-scale astrophysical neutrinos in KamLAND presented as an excess in the number of coincident neutrino interactions associated with the publicly available high-energy neutrino datasets from the IceCube Neutrino Observatory. We find no statistically significant excess in the number of observed low-energy electron antineutrinos in KamLAND, given a coincidence time window of ±500 s, ±1,000 s, ±3,600 s, and ±10,000 s around each of the IceCube neutrinos. We use this observation to present limits from 1.8 MeV to 100 MeV on the electron antineutrino fluence, assuming a mono-energetic flux. We then compare the results to several astrophysical measurements performed by IceCube and place a limit at the 90% confidence level on the electron antineutrino isotropic thermal luminosity from the TXS 0506+056 blazar. Copyright © 2022, The Authors. All rights reserved.

关键词： Electrons

Structural insights into light harvesting by antenna-containing rhodopsins in marine Asgard archaea

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Nature microbiology 2025年第6期10卷 1484-1500页

作者： Gali Tzlil María Del Carmen Marín Yuma Matsuzaki Probal Nag Shota Itakura Yosuke Mizuno Shunya Murakoshi Tatsuki Tanaka Shirley Larom Masae Konno Rei Abe-Yoshizumi Ana Molina-Márquez Daniela Bárcenas-Pérez José Cheel Michal Koblížek Rosa León Kota Katayama Hideki Kandori Igor Schapiro Wataru Shihoya Osamu Nureki Keiichi Inoue Andrey Rozenberg Ariel Chazan Oded Béjà Faculty of Biology Technion-Israel Institute of Technology Haifa Israel. Physical and Analytical Chemistry Department University of Jaén Jaén Spain. Department of Biological Sciences Graduate School of Science The University of Tokyo Tokyo Japan. Fritz Haber Center for Molecular Dynamics Research Institute of Chemistry The Hebrew University of Jerusalem Jerusalem Israel. Department of Life Science and Applied Chemistry Nagoya Institute of Technology Nagoya Japan. The Institute for Solid State Physics The University of Tokyo Kashiwa Japan. Laboratory of Biochemistry and Molecular Biology Faculty of Experimental Sciences Marine International Campus of Excellence (CEIMAR) University of Huelva Huelva Spain. Centre Algatech Institute of Microbiology Czech Academy of Sciences Třeboň Czech Republic. Faculty of Science University of South Bohemia České Budějovice Czech Republic. OptoBioTechnology Research Center Nagoya Institute of Technology Nagoya Japan. Department of Physics Technische Universität Dortmund Germany. Research Center Chemical Sciences and Sustainability University Alliance Ruhr Bochum Germany. Department of Biological Sciences Graduate School of Science The University of Tokyo Tokyo Japan. wtrshh9@***. Department of Biological Sciences Graduate School of Science The University of Tokyo Tokyo Japan. nureki@bs.s.u-tokyo.ac.jp. The Institute for Solid State Physics The University of Tokyo Kashiwa Japan. inoue@issp.u-tokyo.ac.jp. Faculty of Biology Technion-Israel Institute of Technology Haifa Israel. alephreish@***. Faculty of Biology Technion-Israel Institute of Technology Haifa Israel. achazan@ethz.ch. Institute of Environmental Engineering ETH Zurich Switzerland. achazan@ethz.ch. Faculty of Biology Technion-Israel Institute of Technology Haifa Israel. beja@technion.ac.il. The Nancy and Stephen Grand Technion Energy Program (GTEP) Technion-Israel Institute of Technology Haifa Israel. beja@technion.ac.il.

Aquatic bacterial rhodopsin proton pumps harvest light energy for photoheterotrophic growth and are known to contain hydroxylated carotenoids that expand the wavelengths of light utilized, but these have not been characterized in marine archaea. Here, by combining a marine chromophore extract with purified archaeal rhodopsins identified in marine metagenomes, we show light energy transfer from diverse hydroxylated carotenoids to heimdallarchaeial rhodopsins (HeimdallRs) from uncultured marine planktonic members of 'Candidatus Kariarchaeaceae' ('Candidatus Asgardarchaeota'). These light-harvesting antennas absorb in the blue-light range and transfer energy to the green-light-absorbing retinal chromophore within HeimdallRs, enabling the use of light that is otherwise unavailable to the rhodopsin. Furthermore, we show elevated proton pumping by the antennas in HeimdallRs under white-light illumination, which better simulates the light conditions encountered by these archaea in their natural habitats. Our results indicate that light-harvesting antennas in microbial rhodopsins exist in families beyond xanthorhodopsins and proteorhodopsins and are present in both marine bacteria and archaea.

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physics Performance of the Large-Sized Telescope prototype of the Cherenkov Telescope Array 37

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Physics Performance of the Large-Sized Telescope prototype o...

37th International Cosmic Ray Conference, ICRC 2021

作者： Abe, H. Aguasca, A. Agudo, I. Antonelli, L.A. Aramo, C. Armstrong, T. Artero, M. Asano, K. Ashkar, H. Aubert, P. Baktash, A. Bamba, A. Baquero Larriva, A. Baroncelli, L. Barres de Almeida, U. Barrio, J.A. Batkovic, I. Becerra González, J. Bernardos, M.I. Berti, A. Biederbeck, N. Bigongiari, C. Blanch, O. Bonnoli, G. Bordas, P. Bose, D. Bulgarelli, A. Burelli, I. Buscemi, M. Cardillo, M. Caroff, S. Carosi, A. Cassol, F. Cerruti, M. Chai, Y. Cheng, K. Chikawa, M. Chytka, L. Contreras, J.L. Cortina, J. Costantini, H. Dalchenko, M. De Angelis, A. de Bony de Lavergne, M. Deleglise, G. Delgado, C. Delgado Mengual, J. della Volpe, D. Depaoli, D. Di Pierro, F. Di Venere, L. Díaz, C. Dominik, R.M. Dominis Prester, D. Donini, A. Dorner, D. Doro, M. Elsässer, D. Emery, G. Escudero, J. Fiasson, A. Foffano, L. Fonseca, M.V. Freixas Coromina, L. Fukami, S. Fukazawa, Y. Garcia, E. Garcia López, R. Giglietto, N. Giordano, F. Gliwny, P. Godinovic, N. Green, D. Grespan, P. Gunji, S. Hackfeld, J. Hadasch, D. Hahn, A. Hassan, T. Hayashi, K. Heckmann, L. Heller, M. Herrera Llorente, J. Hirotani, K. Hoffmann, D. Horns, D. Houles, J. Hrabovsky, M. Hrupec, D. Hui, D. Hütten, M. Inada, T. Inome, Y. Iori, M. Ishio, K. Iwamura, Y. Jacquemont, M. Jimenez Martinez, I. Jouvin, L. Jurysek, J. Kagaya, M. Karas, V. Katagiri, H. Kataoka, J. Kerszberg, D. Kobayashi, Y. Kong, A. Kubo, H. Kushida, J. Lamanna, G. Lamastra, A. Le Flour, T. Longo, F. López-Coto, R. López-Moya, M. López-Oramas, A. Luque-Escamilla, P.L. Majumdar, P. Makariev, M. Mandat, D. Manganaro, M. Mannheim, K. Mariotti, M. Marquez, P. Marsella, G. Martí, J. Martinez, O. Martínez, G. Martínez, M. Marusevec, P. Mas, A. Maurin, G. Mazin, D. Mestre Guillen, E. Micanovic, S. Miceli, D. Miener, T. Miranda, J.M. Miranda, L.D.M. Mirzoyan, R. Mizuno, T. Molina, E. Montaruli, T. Monteiro, I. Moralejo, A. Morcuende, D. Moretti, E. Morselli, A. Mrakovcic, K. Murase, K. Nagai, A. Nakamori, T. Nickel, L. Nieto, D. Institute for Cosmic Ray Research University of Tokyo 5-1-5 Kashiwa-no-ha Kashiwa Chiba277-8582 Japan Departament de Física Quàntica i Astrofísica Institut de Ciències del Cosmos Universitat de Barcelona IEEC-UB Spain Instituto de Astrofísica de Andalucía-CSIC Granada18080 Spain INAF Osservatorio Astronomico di Roma Italy INFN Sezione di Napoli Italy Aix Marseille Univ CNRS IN2P3 CPPM France 08193 Spain IRFU CEA Université Paris-Saclay France LAPP Univ. Grenoble Alpes Univ. Savoie Mont Blanc CNRS-IN2P3 9 Chemin de Bellevue - BP 110 AnnecyCedex 74941 France Universität Hamburg Institut für Experimentalphysik Germany Graduate School of Science University of Tokyo Japan EMFTEL Department IPARCOS Universidad Complutense de Madrid MadridE-28040 Spain INAF Osservatorio di Astrofisica e Scienza Spazio di Bologna Italy Centro Brasileiro de Pesquisas Físicas Brazil INFN Sezione di Padova PadovaI-35131 Italy Università degli Studi di Padova Via Marzolo 8 Padova35131 Italy Instituto de Astrofísica de Canarias Departamento de Astrofísica Universidad de La Laguna Spain Max-Planck-Institut für Physik München80805 Germany Department of Physics TU Dortmund University Otto-Hahn-Str. 4 Dortmund44221 Germany Saha Institute of Nuclear Physics INFN Sezione di Trieste Università degli Studi di Udine Italy INFN Sezione di Catania Italy Italy University of Geneva Département de Physique Nucléaire et Corpusculaire Switzerland Palacky University Olomouc Faculty of Science Czech Republic CIEMAT Port d'Informació Científica Spain INFN Sezione di Torino via P. Giuria 1 Torino10125 Italy Dipartimento di Fisica Universitá degli Studi di Torino Italy INFN Sezione di Bari Università di Bari Italy University of Rijeka Department of Physics Croatia Institute for Theoretical Physics and Astrophysics Universität Würzburg Germany Physics Program Graduate School of Advanced Science and Engineering Hiroshima University Japan INFN Sezione di Bari Politecnico di B

The Large-Sized Telescope (LST) prototype of the future Cherenkov Telescope Array (CTA) is located at the Northern site of CTA, on the Canary Island of La Palma. It is designed to provide optimal performance in the lowest part of the energy range covered by CTA, observing gamma rays down to energies of tens of GeV. The LST prototype started performing astronomical observations in November 2019 during the commissioning of the telescope and it has been taking data since then. In this contribution, we will present the tuning of the characteristics of the telescope in the Monte Carlo (MC) simulations to describe the data obtained, the estimation of its angular and energy resolution, and an evaluation of its sensitivity, both with simulations and with observations of the Crab Nebula. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0)

关键词： Telescopes

No external load measurement strategy for micro thermoelectric generator based on high-performance Si_(1-x-y)Ge_(x)Sn_(y) film

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Journal of Materiomics 2021年第4期7卷 665-671页

作者： Ying Peng Sijing Zhu Huajun Lai Jie Gao Masashi Kurosawa Osamu Nakatsuka Sakae Tanemura Biaolin Peng Lei Miao Guangxi Key Laboratory of Information Material School of Material Science and EngineeringGuilin University of Electronic TechnologyGuilin541004China Department of Materials Physics Graduate School of EngineeringNagoya UniversityNagoya464-8603Japan PRESTO Japan Science and Technology Agency4-1-8HonchoKawaguchiSaitama332-0012Japan Institute of Materials and Systems for Sustainability Nagoya UniversityNagoya464-8601Japan Japan Fine Ceramics Center 2-4-1 MutsunoAtsuta-kuNagoya456-8587Japan Center on Nanoenergy Research Guangxi Key Laboratory of Processing for Non-ferrous Metal and Featured MaterialsGuangxi Key Laboratory for Relativity AstrophysicsNanning530004China Department of Materials Science and Engineering SIT Research LaboratoriesInnovative Global ProgramFaculty of EngineeringShibaura Institute of TechnologyTokyo135-8548Japan

In this study,a micro in-plane p-type thermoelectric generator(TEG),which consists of thin-film Si_(1-x-y)Ge_(x)Sn_(y) ternary alloy semiconductor on insulator,is developed to make efficient use of waste heat such as human body.A power factor value as high as 1095 mWm^(-1) K^(-2) had been achieved using Bion implanted and short-term rapid thermal annealing(RTA)*** addition,a measuring scheme for micro TEG without external load resistance was *** one measuring session,multiple parameters can be *** micro single-arm TEG prepared by semiconductor process can output 0.29 nW power at a temperature difference of 15 K,and a cross-sectional power density has reached up to 0.58 mW/cm^(2),which is a superior value for wearable *** findings of this study have important reference value for wearable device performance improvement and output power measuring of micro TEG.

关键词： Si_(1-x-y)Ge_(x)Sn_(y) film P-type TEG No external load measurement Ambient power density

EMPRESS. XIV. Strong High Ionization Lines of Young Galaxies at z = 0 − 8: Ionizing Spectra Consistent with the Intermediate Mass Black Holes with MBH ∼ 103 − 106 M☉

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arXiv 2023年

作者： Hatano, Shun Ouchi, Masami Umeda, Hiroya Nakajima, Kimihiko Kawaguchi, Toshihiro Isobe, Yuki Aoyama, Shohei Watanabe, Kuria Harikane, Yuichi Kusakabe, Haruka Matsumoto, Akinori Moriya, Takashi J. Nishigaki, Moka Ono, Yoshiaki Onodera, Masato Sugahara, Yuma Suzuki, Akihiro Xu, Yi Zhang, Yechi National Astronomical Observatory of Japan Osawa 2-21-1 Mitaka Tokyo181-8588 Japan Department of Astronomical Science The Graduate University for Advanced Studies SOKENDAI 2-21-1 Osawa Mitaka Tokyo181-8588 Japan Institute for Cosmic Ray Research The University of Tokyo 5-1-5 Kashiwanoha Chiba Kashiwa277-8582 Japan Astronomical Science Program Graduate Institute for Advanced Studies SOKENDAI 2-21-1 Osawa Mitaka Tokyo181-8588 Japan University of Tokyo Chiba Kashiwa277-8583 Japan Department of Physics Graduate School of Science The University of Tokyo 7-3-1 Hongo Bunkyo Tokyo113-0033 Japan Department of Economics Management and Information Science Onomichi City University Hisayamada 1600-2 Onomichi Hiroshima722-8506 Japan Institute of Management and Information Technologies Chiba University 1-33 Yayoi-cho Inage-ward Chiba263-8522 Japan Observatoire de Genéve Université de Genéve 51 Ch. des Maillettes Versoix1290 Switzerland School of Physics and Astronomy Faculty of Science Monash University ClaytonVIC3800 Australia 650 North A’ohoku Place HiloHI96720 United States Waseda Research Institute for Science and Engineering Faculty of Science and Engineering Waseda University 3-4-1 Okubo Shinjuku Tokyo169-8555 Japan Research Center for the Early Universe The University of Tokyo 7-3-1 Hongo Bunkyo Tokyo113-0033 Japan Department of Astronomy Graduate School of Science the University of Tokyo 7-3-1 Hongo Bunkyo Tokyo113-0033 Japan

We present ionizing spectra estimated at 13.6–100 eV for ten dwarf galaxies with strong high ionization lines of He iiλ4686 and [Ne v]λ3426 ([Ne iv]λ2424) at z = 0 (z = 8) that are identified in our Keck/LRIS spectroscopy and the literature (the JWST ERO program). With the flux ratios of these high ionization lines and > 10 low-ionization lines of hydrogen, helium, oxygen, neon, and sulfur, we determine ionizing spectra consisting of stellar and non-thermal power-law radiation by photoionization modeling with free parameters of nebular properties including metallicity and ionization parameter, cancelling out abundance ratio differences. We find that all of the observed flux ratios are well reproduced by the photoinization models with the power law index αEUV of αEUV ∼ (−1) − 0 and the luminosity LEUV of LEUV ∼ 1040 − 1042 erg s−1 at ∼ 55 − 100 eV for six galaxies, while four galaxies include large systematics in αEUV caused by stellar radiation contamination. We then compare αEUV and LEUV of these six galaxies with those predicted by the black hole (BH) accretion disk models, and find that αEUV and LEUV are similar to those of the intermediate mass black holes (IMBHs) in BH accretion disk models albeit with possibilities of the other scenarios. Confirming these results with a known IMBH having a mass MBH of MBH = 105.75 M☉, we find that four local galaxies and one z = 7.665 galaxy have ionizing spectra consistent with those of IMBHs with MBH ∼ 103 − 105 M☉. Copyright © 2023, The Authors. All rights reserved.

关键词： Galaxies

Saturable Time-Varying Mirror Based on an Epsilon-Near-Zero Material

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Physical Review Applied 2022年第5期18卷 054067-054067页

作者： Romain Tirole Emanuele Galiffi Jakub Dranczewski Taran Attavar Benjamin Tilmann Yao-Ting Wang Paloma A. Huidobro Andrea Alú John B. Pendry Stefan A. Maier Stefano Vezzoli Riccardo Sapienza The Blackett Laboratory Department of Physics Imperial College London London SW7 2BW United Kingdom Photonics Initiative Advanced Science Research Center City University of New York 85 St. Nicholas Terrace New York New York 10031 USA Chair in Hybrid Nanosystems Nanoinstitut München Ludwig-Maximilians-Universität München München 80539 Germany Instituto de Telecomunicações Instituto Superior Tecnico-University of Lisbon Avenida Rovisco Pais 1 Lisboa 1049-001 Portugal Physics Program Graduate Center City University of New York New York New York 10016 USA School of Physics and Astronomy Monash University Clayton 3800 Victoria Australia

We report a switchable time-varying mirror, composed of an indium-tin-oxide–gold bilayer, displaying a tenfold modulation of reflectivity (ΔR≈0.6), which saturates for a driving-pump intensity Ipump≈100GW/cm2. Upon interacting with the saturated time-varying mirror, the frequency content of a reflected pulse is extended up to 31 THz, well beyond the pump spectral content (2.8 THz). We interpret the spectral broadening as a progressive shortening of the mirror rise time from 110 fs to below 30 fs with increasing pump power, which is confirmed by four-wave-mixing experiments and partially captured by a linear time-varying model of the mirror. A temporal response unbounded by the pump bandwidth enables applications for spectral manipulation from time-varying systems with impact for communication networks, optical switching, and computing.

关键词： Metasurfaces Nanophotonics Third order nonlinear optical processes Ultrafast optics Bilayer films Femtosecond laser irradiation Four-wave mixing Pump-probe spectroscopy

Stationary Charge Radiation in Anisotropic Photonic Time Crystals

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arXiv 2022年

作者： Li, Huanan Yin, Shixiong He, Huan Xu, Jingjun Alù, Andrea Shapiro, Boris MOE Key Laboratory of Weak-Light Nonlinear Photonics School of Physics Nankai University Tianjin300071 China Photonics Initiative Advanced Science Research Center City University of New York New YorkNY10031 United States 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 Department of Physics Technion-Israel Institute of Technology Haifa32000 Israel

Time metamaterials exhibit a great potential for wave manipulation, drawing increasing attention in recent years. Here, we explore the exotic wave dynamics of an anisotropic photonic time crystal (APTC), formed by an anisotropic medium whose optical properties are uniformly and periodically changed in time. Based on a temporal transfer matrix formalism, we show that a stationary charge embedded in an APTC emits radiation, in contrast to the case of isotropic photonic time crystals, and its distribution in momentum space is controlled by the APTC band structure. Our approach extends the functionalities of time metamaterials, offering new opportunities for radiation generation and control, with implications for both classical and quantum applications. Copyright © 2022, The Authors. All rights reserved.

关键词： Metamaterials

Landau Polaritons in the Ultrastrong and Superstrong Coupling Regime in a Multimode Terahertz Photonic-Crystal Cavity

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Landau Polaritons in the Ultrastrong and Superstrong Couplin...

International Conference on Infrared and Millimeter Waves

作者： Fuyang Tay Ali Mojibpour Stephen Sanders Shuang Liang Hongjing Xu Geoff C. Gardner Andrey Baydin Michael J. Manfra Alessandro Alabastri David Hagenmüller Junichiro Kono Department of Electrical and Computer Engineering Rice University Houston TX USA Applied Physics Graduate Program Smalley–Curl Institute Rice University Houston TX USA Department of Physics and Astronomy Purdue University West Lafayette IN USA Birck Nanotechnology Center Purdue University West Lafayette IN USA Department of Physics and Astronomy Rice University Houston TX USA Smalley–Curl Institute Rice University Houston TX USA School of Electrical and Computer Engineering Purdue University West Lafayette IN USA School of Materials Engineering Purdue University West Lafayette IN USA ISIS (UMR 7006) Université de Strasbourg and CNRS Strasbourg France Department of Materials Science and NanoEngineering Rice University Houston TX USA

We have demonstrated ultrastrong and superstrong coupling of a Landau-quantized two-dimensional electron gas in GaAs with a multiple-mode three-dimensional terahertz photonic-crystal cavity. The cavity had an asymmetric design such that the real-space profiles of photonic modes depended on the electric field polarization. Terahertz magnetospectroscopy experiments with polarized radiation clearly showed that the degree of hybridization of multiple cavity modes is a function of the spatial overlap of the photonic modes. These findings can be utilized for the dynamical tuning of multimode light–matter interactions, which can lead to the development of novel terahertz devices.

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Observation of Temporal Reflections and Broadband Frequency Translations at Photonic Time-Interfaces

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arXiv 2022年

作者： Moussa, Hady Xu, Gengyu Yin, Shixiong Galiffi, Emanuele Ra'di, Younes Alù, Andrea Photonics Initiative Advanced Science Research Center City University of New York New YorkNY10031 United States Department of Electric Engineering City College of City University of New York New YorkNY10031 United States Department of Electrical Engineering and Computer Science Syracuse University SyracuseNY13244 United States Physics Program Graduate Center City University of New York New YorkNY10016 United States

Time-reflection is a uniform inversion of the temporal evolution of a signal, which arises when an abrupt change in the properties of the host material occurs uniformly in space.1-3 At such a time-interface, a portion of the input signal is time-reversed, and its frequency spectrum is homogeneously translated while its momentum is conserved, forming the temporal counterpart of a spatial interface. Combinations of time-interfaces, forming time-metamaterials and Floquet matter4, exploit the interference of multiple time-reflections for extreme wave manipulation, leveraging time as a new degree of freedom5. Here, we report the observation of photonic time-reflection and associated broadband frequency translation in a switched transmission-line metamaterial whose effective capacitance is homogeneously and abruptly changed via a synchronized array of switches. A pair of temporal interfaces are combined to demonstrate time-reflection-induced wave interference, realizing the temporal counterpart of a Fabry-Perot cavity6. Our results establish the foundational building blocks to realize time-metamaterials and Floquet photonic crystals, with opportunities for extreme photon manipulation in space and time7-8 © 2022, CC BY.

关键词： Metamaterials