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Synthetic helicoidal rotation of a quasielectrostatic ring resonator for ultrabroadband magnet-free nonreciprocity

Physical Review Applied 2024年第6期22卷 064020-064020页

作者： Aravind Nagulu Ahmed Mekawy Mykhailo Tymchenko Dimitrios Sounas Harish Krishnaswamy Andrea Alù Department of Electrical and Systems Engineering Washington University in St. Louis St. Louis Missouri 63130 USA Photonics Initiative Advanced Science Research Center City University of New York New York New York 10031 USA Department of Electrical and Computer Engineering The University of Texas at Austin Austin Texas 78712 USA Department of Electrical Engineering Wayne State University Detroit Michigan 48202 USA Department of Electrical Engineering Columbia University New York New York 10027 USA Physics Program Graduate Center City University of New York New York New York 10016 USA

Suitably tailored forms of spatiotemporal modulation in electronic circuit networks have been recently employed to overcome fundamental challenges in modern electronic systems, including breaking reciprocity, squeezing the footprint of high-Q resonators, and overcoming the delay-bandwidth limit. Rotating patterns of temporal modulations have been used to synthesize angular momentum, which replaces magnetic bias to break reciprocity in integrated circuits. However, this approach is limited by trade-offs between modulation speed, footprint, and bandwidth of operation. Rotating switching patterns in commutated capacitor networks also enables compact filters and quasielectrostatic wave propagation, overcoming the delay-bandwidth limit. In this paper, we combine these mechanisms in an integrated-circuit ring that synthetically rotates in two dimensions, realizing an effective helicoidal motion that provides ultrabroadband quasielectrostatic nonreciprocal responses fitting within a theoretically infinitesimal size. We also analyze the impact of modulation signal noise on time-modulated nonreciprocal components and unveil the role of a dynamic noise mechanism based on which the noise level increases in the presence of a strong signal passing through the component, along with methods to mitigate this effect. We experimentally verify these principles in a three-port integrated circulator based on a 65-nm CMOS process that operates from dc to 1 GHz with a miniaturization factor of 2 × 106.

关键词： Metamaterials Non-reciprocal transmission Photonics Topolectrical circuits

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Excitation of absorbing exceptional points in the time domain

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Physical Review A 2022年第3期106卷 L031503-L031503页

作者： Asaf Farhi Ahmed Mekawy Andrea Alù Douglas Stone Department of Applied Physics Yale University New Haven Connecticut 06520 USA Photonics Initiative Advanced Science Research Center City University of New York New York New York 10031 USA Department of Electrical Engineering City College of the 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 Yale Quantum Institute Yale University New Haven Connecticut 06520 USA

We analyze the time-domain dynamics of resonators supporting exceptional points (EPs), at which both the eigenfrequencies and the eigenmodes associated with perfect capture of an input wave coalesce. We find that a time-domain signature of the EP is an expansion of the class of waveforms which can be perfectly captured. We show that such resonators have improved performance for storage or transduction of energy. They also can be used to convert between waveforms within this class. We analytically derive these features and demonstrate them for several examples of coupled optical resonator systems.

关键词： Classical optics Geometrical & wave optics Lasers Light-matter interaction Photonics Scattering theory Bragg structures Complex media Optical microcavities Waveguides

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Atmospheric retrieval of Subaru/IRD high-resolution spectrum of the archetype T-type brown dwarf Gl 229 B∗

arXiv

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arXiv 2024年

作者： Kawashima, Yui Kawahara, Hajime Kasagi, Yui Ishikawa, Hiroyuki Tako Masuda, Kento Kotani, Takayuki Kudo, Tamoyuki Hirano, Teruyuki Kuzuhara, Masayuki Nugroho, Stevanus K. Livingston, John Harakawa, Hiroki Nishikawa, Jun Omiya, Masashi Takarada, Takuya Tamura, Motohide Ueda, Akitoshi Department of Astronomy Graduate School of Science Kyoto University Kitashirakawa Oiwake-cho Sakyo-ku Kyoto606-8502 Japan Frontier Research Institute for Interdisciplinary Sciences Tohoku University 6-3 Aramaki aza Aoba Aoba-ku Sendai Miyagi980-8578 Japan Department of Geophysics Graduate School of Science Tohoku University 6-3 Aramaki aza Aoba Aoba-ku Sendai Miyagi980-8578 Japan Institute of Space and Astronautical Science Japan Aerospace Exploration Agency 3-1-1 Yoshinodai Chuo-ku Kanagawa Sagamihara252-5210 Japan Cluster for Pioneering Research RIKEN 2-1 Hirosawa Wako Saitama351-0198 Japan Department of Astronomy Graduate School of Science The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo113-0033 Japan Department of Physics and Astronomy The University of Western Ontario 1151 Richmond St LondonONN6A 3K7 Canada Department of Earth and Space Science Graduate School of Science Osaka University 1-1 Machikaneyama-cho Toyonaka Osaka560-0043 Japan Astrobiology Center 2-21-1 Osawa Mitaka Tokyo181-8588 Japan Astronomical Science Program The Graduate University for Advanced Studies SOKENDAI 2-21-1 Osawa Mitaka Tokyo181-8588 Japan National Astronomical Observatory of Japan 2-21-1 Osawa Mitaka Tokyo181-8588 Japan Subaru Telescope 650 N. Aohoku Place HiloHI96720 United States

Brown dwarfs provide a unique opportunity to study atmospheres and their physical and chemical processes with high precision, especially in temperature ranges relevant to exoplanets. In this study, we performed high-resolution (R ∼ 70,000) spectroscopy using Subaru/IRD of Gl 229 B, the first discovered T-type (T7.0p) brown dwarf, which orbits an M1V host star at a separation of 33 au. We conducted atmospheric retrieval on the reduced H-band spectrum using the high-resolution spectrum model compatible with automatic differentiation and GPU, ExoJAX. In contrast to previous retrieval studies on medium-resolution spectra, we obtained a C/O ratio consistent with that of the host star, aligning with the expected formation process for such a massive brown dwarf. Additionally, based on the strong constraint on temperature from the high-resolution spectrum and previously measured photometric magnitude, our analysis indicates that Gl 229 B is a binary, which was also proposed by Brandt et al. (2021). Finally, we validated current molecular line lists by leveraging the obtained high-precision, high-resolution spectrum of this warm (∼ 900 K) atmosphere. This study highlights the importance of observing companion brown dwarfs as benchmark objects for establishing characterization techniques for low-mass objects and enhancing our understanding of their atmospheres, given the wealth of available information and the relative ease of observation. Copyright © 2024, The Authors. All rights reserved.

关键词： Stars

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Cementing the grain boundary defects in the strain relaxed mixed Sn-Pb perovskite solar cells

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Chemical Engineering Journal 2025年 516卷

作者： Kumar, Abhishek Ansari, Zeeshan Alam Hanmandlu, Chintam Banerjee, Soumallya Chen, Yu-Te Yang, Po-Yu Musa, Ahmed Fouad You, Yun-Wen Pao, Chun-Wei Wei, Tzu-Chien Shyue, Jing-Jong Lu, Yu-Jung Chu, Chih-Wei Department of Physics National Taiwan University Sec. 4 Roosevelt Road Taipei106 Taiwan Research Center for Applied Sciences Academia Sinica 128 Academia Road Section 2 Taipei Nangang11529 Taiwan Nano-Science and Technology Program Taiwan International Graduate Program Academia Sinica Taipei106 Taiwan Department of Materials Science and Engineering National Yang Ming Chiao Tung University Hsinchu300 Taiwan Department of Chemical Engineering National Tsing Hua University 101 Section 2 Kuang-Fu Road Hsinchu City300044 Taiwan College of Engineering Center for Green Technology Chang Gung University Taoyuan City333002 Taiwan Department of Photonics National Yang Ming Chiao Tung University Hsinchu City30010 Taiwan Institute of Applied Mechanics National Taiwan University Sec. 4 Roosevelt Road Taipei106 Taiwan

Mixed Tin-lead (Sn-Pb) perovskite solar cells (PSCs) offer a promising avenue for achieving high power conversion efficiencies (PCEs) due to their narrow bandgaps and substantial optical absorption in the visible–near-infrared region. However, the disparated reaction kinetics of PbI2 and SnI2 with organic salts, resulting in an uneven spatial distribution of Sn2+ and Pb2+ within the perovskite lattice, inducing micro-strain in the film and a Sn-rich surface vulnerable to oxidation-Sn2+ to Sn4+, thereby elevating nonradiative recombination. Here, we report the incorporation of 2,5-Dibromo-3,4-pyridinediamine (DBPDA) as an additive in the mixed Sn-Pb perovskite precursor solution, designed to mitigate micro-strain formation, reduce defect density by suppressing Sn4+ formation, and enhance the passivation of undercoordinated Sn/Pb species through synergistic bonding interaction. The best performing PSCs achieved an impressive PCE of 21.24 % with a high open circuit voltage (Voc) of 0.85 V, alongside significantly improved long-term stability, retaining near 80 % of their initial PCE after 1,008 h in a nitrogen-filled glovebox without encapsulation. In contrast, the control devices retained only 18 % of their initial efficiency under identical conditions. Additionally, an enhanced field effect hole mobility, increasing from 0.18 cm2/V-s in the control film to 1.43 cm2/V-s in the target film, was achieved in mixed Sn-Pb perovskite thin film transistors (TFTs) using these films as active layers. These findings present a viable strategy for strain-relieved perovskite films, enabling stable and high-performance mixed Sn-Pb PSCs and TFTs. © 2025 Elsevier B.V.

关键词： Crystallization kinetics

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Solving integral equations in free-space with inverse-designed ultrathin optical metagratings

arXiv

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arXiv 2022年

作者： Cordaro, Andrea Edwards, Brian Nikkhah, Vahid Alù, Andrea Engheta, Nader Polman, Albert Institute of Physics University of Amsterdam Science Park 904 Amsterdam1098 XH Netherlands Center for Nanophotonics NWO-Institute AMOLF Science Park 104 Amsterdam1098 XG Netherlands Department of Electrical and Systems Engineering University of Pennsylvania PhiladelphiaPA19104 United States Photonics Initiative Advanced Science Research Center City University of New York New YorkNY10031 United States Physics Program Graduate Center City University of New York New YorkNY10016 United States

As standard microelectronic technology approaches fundamental limitations in speed and power consumption, novel computing strategies are strongly needed. Analog optical computing enables processing large amounts of data at a negligible energy cost and high speeds. Based on these principles, ultrathin optical metasurfaces have been recently explored to process large images in real-time, in particular for edge detection. By incorporating feedback, it has also been recently shown that metamaterials can be tailored to solve complex mathematical problems in the analog domain, although these efforts have so far been limited to guided-wave systems and bulky setups. Here, we present an ultrathin Si metasurface-based platform for analog computing that is able to solve Fredholm integral equations of the second kind using free-space visible radiation. A Si-based metagrating was inverse-designed to implement the scattering matrix synthesizing a prescribed Kernel corresponding to the mathematical problem of interest. Next, a semi-transparent mirror was incorporated into the sample to provide adequate feedback and thus perform the required Neumann series, solving the corresponding equation in the analog domain at the speed of light. Visible wavelength operation enables a highly compact, ultrathin device that can be interrogated from free-space, implying high processing speeds and the possibility of on-chip integration. Copyright © 2022, The Authors. All rights reserved.

关键词： Integral equations

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One-loop partition function of gravity with leaky boundary conditions

arXiv

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arXiv 2023年

作者： Grumiller, Daniel Ruzziconi, Romain Zwikel, Céline Institute for Theoretical Physics TU Wien Wiedner Hauptstrasse 8-10/136 ViennaA-1040 Austria Theoretical Sciences Visiting Program Okinawa Institute of Science and Technology Graduate University Onna904-0495 Japan Mathematical Institute University of Oxford Andrew Wiles Building Radcliffe Observatory Quarter Woodstock Road OxfordOX2 6GG United Kingdom Perimeter Institute for Theoretical Physics 31 Caroline Street North WaterlooONN2L 2Y5 Canada

Leaky boundary conditions in asymptotically AdS spacetimes are relevant to discuss black hole evaporation and the evolution of the Page curve via the island formula. We explore the consequences of leaky boundary conditions on the one-loop partition function of gravity. We focus on JT gravity minimally coupled to a scalar field whose normalizable and non-normalizable modes are both turned on, allowing for leakiness through the AdS boundary. Classically, this yields a flux-balance law relating the scalar news to the time derivative of the mass. Semi-classically, we argue that the usual diffeomorphism-invariant measure is ill-defined, suggesting that the area-non-preserving diffeomorphisms are broken at one loop. We calculate the associated anomaly and its implication on the gravitational Gauss law. Finally, we generalize our arguments to higher dimensions and dS. Copyright © 2023, The Authors. All rights reserved.

关键词： Gravitation

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Reducing system dimensionality with long-range collective dipole-dipole interactions

arXiv

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arXiv 2023年

作者： Boddeti, Ashwin K. Wang, Yi Juarez, Xitlali G. Boltasseva, Alexandra Odom, Teri W. Shalaev, Vladimir Alaeian, Hadiseh Jacob, Zubin Elmore Family School of Electrical and Computer Engineering Purdue University West LafayetteIN47907 United States Birck Nanotechnology Center Purdue University West LafayetteIN47907 United States Graduate Program in Applied Physics Northwestern University EvanstonIL60208 United States Department of Materials Science and Engineering Northwestern University EvanstonIL60208 United States Department of Chemistry Northwestern University EvanstonIL60208 United States School of Physics and Astronomy Purdue University West LafayetteIN47907 United States

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 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. © 2023, CC0.

关键词： Dipole moment

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Merger and Postmerger of Binary Neutron Stars with a Quark-Hadron Crossover Equation of State

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Physical Review Letters 2022年第18期129卷 181101-181101页

作者： Yong-Jia Huang Luca Baiotti Toru Kojo Kentaro Takami Hajime Sotani Hajime Togashi Tetsuo Hatsuda Shigehiro Nagataki Yi-Zhong Fan Key Laboratory of Dark Matter and Space Astronomy Purple Mountain Observatory Chinese Academy of Science Nanjing 210023 China School of Astronomy and Space Sciences University of Science and Technology of China Hefei Anhui 230026 China RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS) RIKEN Wako 351-0198 Japan International College and Graduate School of Science Osaka University 1-2 Machikaneyama-cho Toyonaka Osaka 560-0043 Japan Key Laboratory of Quark and Lepton Physics (MOE) and Institute of Particle Physics Central China Normal University Wuhan 430079 China Department of Physics Tohoku University Sendai 980-8578 Japan Kobe City College of Technology 651-2194 Kobe Japan RIKEN Astrophysical Big Bang Laboratory (ABBL) Cluster for Pioneering Research Wako Saitama 351-0198 Japan

Fully general-relativistic binary-neutron-star (BNS) merger simulations with quark-hadron crossover (QHC) equations of state (EOS) are studied for the first time. In contrast to EOS with purely hadronic matter or with a first-order quark-hadron phase transition (1PT), in the transition region QHC EOS show a peak in sound speed and thus a stiffening. We study the effects of such stiffening in the merger and postmerger gravitational (GW) signals. Through simulations in the binary-mass range 2.5

关键词： Gravitational waves Nuclear matter in neutron stars Binary stars Neutron stars & pulsars Numerical relativity Numerical simulations in gravitation & astrophysics

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Electron EDM arising from modulus τ in the supersymmetric modular invariant flavor models

arXiv

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arXiv 2021年

作者： Tanimoto, Morimitsu Yamamoto, Kei Department of Physics Niigata University Niigata950-2181 Japan Physics Program Graduate School of Advanced Science and Engineering Hiroshima University Higashi-Hiroshima739-8526 Japan Core of Research for the Energetic Universe Hiroshima University Higashi-Hiroshima739-8526 Japan

The electric dipole moment (EDM) of electron is studied in the supersymmetric A4 modular invariant theory of flavors with CP invariance. The CP symmetry of the lepton sector is broken by fixing the modulus τ. Lepton mass matrices are completely consistent with observed lepton masses and mixing angles in our model. In this framework, a fixed τ also causes the CP violation in the soft SUSY breaking terms. The electron EDM arises from the CP non-conserved soft SUSY breaking terms. The experimental upper bound of the electron EDM excludes the SUSY mass scale below 4-6 TeV depending on five cases of the lepton mass matrices. In order to see the effect of CP phase of the modulus τ, we examine the correlation between the electron EDM and the decay rate of the µ → eγ decay, which is also predicted by the soft SUSY breaking terms. The correlations are clearly predicted in contrast to models of the conventional flavor symmetry. The branching ratio is approximately proportional to the square of |de/e|. The SUSY mass scale will be constrained by the future sensitivity of the electron EDM, |de/e| ' 10−30 cm. Indeed, it could probe the SUSY mass range of 10-20 TeV in our model. Thus, the electron EDM provides a severe test of the CP violation via the modulus τ in the supersymmetric modular invariant theory of flavors. Copyright © 2021, The Authors. All rights reserved.

关键词： Supersymmetry

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Observation of the Magnonic Dicke Superradiant Phase Transition

arXiv

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arXiv 2024年

作者： Kim, Dasom Dasgupta, Sohail Ma, Xiaoxuan Park, Joong-Mok Wei, Hao-Tian Luo, Liang Doumani, Jacques Li, Xinwei Yang, Wanting Cheng, Di Kim, Richard H.J. Everitt, Henry O. Kimura, Shojiro Nojiri, Hiroyuki Wang, Jigang Cao, Shixun Bamba, Motoaki Hazzard, Kaden R.A. Kono, Junichiro Applied Physics Graduate Program Smalley–Curl Institute Rice University HoustonTX77005 United States Department of Electrical and Computer Engineering Rice University HoustonTX77005 United States Ames National Laboratory AmesIA50011 United States Department of Physics and Astronomy Rice University HoustonTX77005 United States Department of Physics International Center of Quantum and Molecular Structures Materials Genome Institute Shanghai University Shanghai200444 China Department of Physics National University of Singapore 117551 Singapore Department of Physics and Astronomy Iowa State University AmesIA50011 United States Smalley–Curl Institute Rice University HoustonTX77005 United States DEVCOM Army Research Laboratory-South HoustonTX77005 United States Institute for Materials Research Tohoku University Sendai980-8577 Japan Department of Physics Yokohama National University Yokohama240-8501 Japan Department of Physics and Astronomy University of California DavisCA95616 United States Department of Materials Science and NanoEngineering Rice University HoustonTX77005 United States

Two-level atoms coupled with single-mode cavity photons are predicted to exhibit a quantum phase transition when the coupling strength exceeds a critical value, entering a phase in which atomic polarization and photonic field are finite even at zero temperature and without external driving. However, this phenomenon, the superradiant phase transition (SRPT), is forbidden by a no-go theorem due to the existence of the diamagnetic term in the Hamiltonian. Here, we present spectroscopic evidence for a magnonic SRPT in ErFeO3, where the role of the photonic mode (two-level atoms) in the photonic SRPT is played by an Fe3+ magnon mode (Er3+ spins). The absence of the diamagnetic term in the Fe3+–Er3+ exchange coupling ensures that the no-go theorem does not apply. Terahertz and gigahertz magnetospectroscopy experiments revealed the signatures of the SRPT – a kink and a softening, respectively, of two spin–magnon hybridized modes at the critical point. Copyright © 2024, The Authors. All rights reserved.

关键词： Phase transitions

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