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arXiv 2025年

作者： Mogi, Masataka Choi, Dongsung Oh, Kyoung Hun Golovanova, Diana Zhao, Yufei Su, Yifan Shen, Zongqi Azoury, Doron Xia, Haoyu Ilyas, Batyr Luo, Tianchuang Kida, Noriaki Osaka, Taito Togashi, Tadashi Yan, Binghai Gedik, Nuh Department of Physics Massachusetts Institute of Technology CambridgeMA United States Department of Applied Physics University of Tokyo Bunkyo-ku Tokyo Japan Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology CambridgeMA United States Max Planck Institute for the Structure and Dynamics of Matter Hamburg Germany Department of Condensed Matter Physics Weizmann Institute of Science Rehovot Israel RIKEN SPring-8 Center Hyogo Sayo Japan Japan Synchrotron Radiation Research Institute Hyogo Sayo Japan

Ultrafast optical excitation provides a powerful route for accessing emergent quantum phases far from equilibrium, enabling transient light-induced phenomena such as magnetism, ferroelectricity, and superconductivity. However, extending this approach to induce topological phases, especially in conventional semiconductors, remains challenging. Here, we report the observation of a thermally inaccessible, transient topological crystalline order in the layered semiconductor SnSe, a trivial insulator with a sizable (~ 0.8 eV) band gap, induced by femtosecond above-gap excitation. Time- and angle-resolved photoemission spectroscopy directly reveals the sub-picosecond emergence of Dirac-like linear dispersions within the band gap. Their features, including a high Fermi velocity (~ 2.5×105 m/s), multiple Dirac points away from high-symmetry momenta, and independence from probe photon energy, are consistent with mirror-symmetry-protected surface states of a topological crystalline insulator. The observed spectral dynamics, combined with density functional theory calculations, indicate that the femtosecond excitation transiently increases lattice symmetry, enabling topological crystalline order to emerge. Our discovery opens new avenues for ultrafast optical control of topological quantum phases in semiconductors, with potential applications in quantum and spintronic devices. Copyright © 2025, The Authors. All rights reserved.

关键词： Energy gap

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Microcomb-Based Digital Holography

Microcomb-Based Digital Holography

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CLEO: Science and Innovations in CLEO 2024, CLEO: S and I 2024 - Part of Conference on Lasers and Electro-Optics

作者： Amann, Stephan Vicentini, Edoardo Xu, Bingxin He, Yang Hänsch, Theodor W. Lin, Qiang Vahala, Kerry Picqué, Nathalie Max-Planck Institute of Quantum Optics Hans-Kopfermann-Str. 1 Garching85748 Germany CIC nanoGUNE BRTA Donostia-San Sebastián Basque Country20018 Spain Department of Electrical and Computer Engineering University of Rochester RochesterNY14627 United States T.J. Watson Laboratory of Applied Physics California Institute of Technology PasadenaCA91125 United States Max-Born Institute for Nonlinear Optics and Short Pulse Spectroscopy Max-Born-Str. 2A Berlin12489 Germany

Lensless three-dimensional hyperspectral imaging is performed with a Kerr comb of 100 GHz line spacing. Broad microcombs will enable an unprecedented combination of long axial range, high precision and fast acquisitio... 详细信息

ISBN: (纸本)9781957171395

关键词： Cameras Electro-optical waveguides Holography Hyperspectral imaging Inspection Laser applications Optics Sensors Surface emitting lasers Ultraviolet sources

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Enhanced Superconducting Qubit Performance Through Ammonium Fluoride Etch

arXiv

引用

arXiv 2024年

作者： Kopas, Cameron J. Goronzy, Dominic P. Pham, Thang Torres Castanedo, Carlos G. Cheng, Matthew Cochrane, Rory Nast, Patrick Lachman, Ella Zhelev, Nikolay Z. Vallières, André Murthy, Akshay A. Oh, Jin-Su Zhou, Lin Kramer, Matthew J. Cansizoglu, Hilal Bedzyk, Michael J. Dravid, Vinayak P. Romanenko, Alexander Grassellino, Anna Mutus, Josh Y. Hersam, Mark C. Yadavalli, Kameshwar Rigetti Computing BerkeleyCA United States Department of Materials Science and Engineering Northwestern University EvanstonIL United States Center for Applied Physics and Superconducting Technologies Northwestern University EvanstonIL United States Department of Physics and Astronomy Northwestern University EvanstonIL United States Department of Physics University of Oregon EugeneOR United States Graduate Program in Applied Physics Northwestern University EvanstonIL60208 United States Fermi National Accelerator Laboratory BataviaIL United States Ames Laboratory U.S. Department of Energy AmesIA United States Northwestern University EvanstonIL United States Department of Chemistry Northwestern University EvanstonIL United States Department of Electrical and Computer Engineering Northwestern University EvanstonIL United States

The performance of superconducting qubits is often limited by dissipation and two-level systems (TLS) losses. The dominant sources of these losses are believed to originate from amorphous materials and defects at interfaces and surfaces, likely as a result of fabrication processes or ambient exposure. Here, we explore a novel wet chemical surface treatment at the Josephson junction-substrate and the substrate-air interfaces by replacing a buffered oxide etch (BOE) cleaning process with one that uses hydrofluoric acid followed by aqueous ammonium fluoride. We show that the ammonium fluoride etch process results in a statistically significant improvement in median T1 by ∼ 22% (p = 0.002), and a reduction in the number of strongly-coupled TLS in the tunable frequency range. Microwave resonator measurements on samples treated with the ammonium fluoride etch prior to niobium deposition also show ∼ 33% lower TLS-induced loss tangent compared to the BOE treated samples. As the chemical treatment primarily modifies the Josephson junction-substrate interface and substrate-air interface, we perform targeted chemical and structural characterizations to examine materials’ differences at these interfaces and identify multiple microscopic changes that could contribute to decreased TLS. © 2024, CC BY-NC-ND.

关键词： Fluorine compounds

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Free electron laser in magnetically dominated regime: simulations with ONEDFEL code

arXiv

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arXiv 2023年

作者： Lyutikov, Maxim Freund, Henry Department of Physics and Astronomy Purdue University 525 Northwestern Avenue West LafayetteIN47907-2036 United States Institute for Research in Electronics and Applied Physics University of Maryland College ParkMD20742 United States Department of Electrical and Computer Engineering University of New Mexico AlbuquerqueNM87131 United States

Using the ONEDFEL code we perform Free Electron Laser simulations in the astrophysically important guide-field dominated regime. For wigglers’ (Alfvén waves) wavelengths of tens of kilometers and beam Lorentz factor ∼ 103, the resulting coherently emitted waves are in the centimeter range. Our simulations show a growth of the wave intensity over fourteen orders of magnitude, over the astrophysically relevant scale of ∼ few kilometers. The signal grows from noise (unseeded). The resulting spectrum shows fine spectral substructures, reminiscent of the ones observed in Fast Radio Bursts (FRBs). Copyright © 2023, The Authors. All rights reserved.

关键词： Free electron lasers

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Fine-Resolution Silicon Photonic Wavelength-Selective Switch Using Hybrid Multimode Racetrack Resonators

arXiv

引用

arXiv 2023年

作者： Cohen, Lucas M. Fatema, Saleha Wankhade, Vivek V. Lingaraju, Navin B. Zhang, Bohan Onural, Deniz Popović, Miloš Weiner, Andrew M. The Purdue Quantum Science and Engineering Institute The Elmore Family School of Electrical and Computer Engineering Purdue University West LafayetteIN47907 United States SRI International ArlingtonVA22209 United States The John Hopkins University Applied Physics Laboratory 11100 Johns Hopkins Rd LaurelMD20723 United States The Department of Electrical and Computer Engineering Boston University BostonMA02215 United States

In this work, we describe a procedure for synthesizing racetrack resonators with large quality factors and apply it to realize a multi-channel wavelength-selective switch (WSS) on a silicon photonic chip. We first determine the contribution of each component primitive to propagation loss in a racetrack resonator and use this data to develop a model for the frequency response of arbitrary order, coupled-racetrack channel dropping filters. We design second-order racetrack filters based on this model and cascade multiple such filters to form a 1×7 WSS. We find good agreement between our model and device performance with second-order racetrack that have ≈ 1 dB of drop-port loss, ≈ 2 GHz FWHM linewidth, and low optical crosstalk due to the quick filter roll-off of ≈ 5.3 dB/GHz. Using a control algorithm, we show three-channel operation of our WSS with a channel spacing of only 10 GHz. Owing to the high quality factor and quick roll-off of our filter design, adjacent channel crosstalk is measured to be © 2023, CC BY.

关键词： Silicon photonics

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Non-Gaussian States Generation Using a High-Speed Single-Pixel Superconducting Nano-Strip Photon-Number-Resolving Detector

Non-Gaussian States Generation Using a High-Speed Single-Pix...

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CLEO: Fundamental Science, CLEO:FS 2024 - Part of Conference on Lasers and Electro-Optics, CLEO 2024

作者： Takahashi, Kazuma Endo, Mamoru Nomura, Takefumi Sonoyama, Tatsuki Kashiwazaki, Takahiro Inoue, Asuka Umeki, Takeshi Yabuno, Masahiro China, Fumihiro Terai, Hirotaka Miki, Shigehito Nehra, Rajveer Takase, Kan Asavanant, Warit Furusawa, Akira Department of Applied Physics School of Engineering The University of Tokyo 7-3-1 Hongo Bunkyo Tokyo113-8656 Japan Optical Quantum Computing Research Team RIKEN Center for Quantum Computing 2-1 Hirosawa Saitama Wako351-0198 Japan NTT Device Technology Labs. NTT Corporation 3-1 Morinosato Wakamiya Kanagawa Atsugi243-0198 Japan Advanced ICT Research Institute National Institute of Information and Communications Technology 588-2 Iwaoka Nishi-ku Hyogo Kobe651-2492 Japan Graduate School of Engineering Kobe University 1-1 Rokkodai-cho Nada-ku Hyogo Kobe657-0013 Japan Department of Electrical and Computer Engineering University of Massachusetts-Amherst AmherstMA01003 United States Department of Physics University of Massachusetts-Amherst AmherstMA01003 United States

ISBN: (纸本)9781957171395

We performed the first non-Gaussian state generation through two photon subtraction with a recently developed single-pixel superconducting nano-strip photon-number-resolving detector. We observed negative values of Wigner function of W(0,1.0) = -0.0072 ± 0.006 without loss correction. © 2024 The Author(s) © Optica Publishing Group 2024.

关键词： Photons

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Channel capacity of the ribosome

引用

Physical Review E 2023年第4期108卷 044404-044404页

作者： Daniel A. Inafuku Kay L. Kirkpatrick Onyema Osuagwu Qier An David A. Brewster Mayisha Zeb Nakib Department of Physics University of Illinois Urbana-Champaign Urbana Illinois 61801 USA Department of Mathematics University of Illinois Urbana-Champaign Urbana Illinois 61801 USA Electrical and Computer Engineering Department Morgan State University Baltimore Maryland 21251 USA Cybersecurity Assurance and Policy Center Morgan State University Baltimore Maryland 21251 USA Department of Physics University of California Santa Barbara Santa Barbara California 93106 USA John A. Paulson School of Engineering and Applied Sciences Harvard University Cambridge Massachusetts 02138 USA

Translation is one of the most fundamental processes in the biological cell. Because of the central role that translation plays across all domains of life, the enzyme that carries out this process, the ribosome, is required to process information with high accuracy. This accuracy often approaches values near unity experimentally. In this paper, we model the ribosome as an information channel and demonstrate mathematically that this biological machine has information-processing capabilities that have not been recognized previously. In particular, we calculate bounds on the ribosome's theoretical Shannon capacity and numerically approximate this capacity. Finally, by incorporating estimates on the ribosome's operation time, we show that the ribosome operates at speeds safely below its capacity, allowing the ribosome to process information with an arbitrary degree of error. Our results show that the ribosome achieves a high accuracy in line with purely information-theoretic means.

关键词： Biomolecular processes Emergent biological functions from complex interactions Gene expression Nucleic acid replication & information processes Biomolecules Enzymes Nucleic acids Peptides Proteins RNA Stochastic analysis

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Increasing the mobility and power-electronics figure of merit of AlGaN with atomically thin AlN/GaN digital-alloy superlattices

arXiv

引用

arXiv 2022年

作者： Pant, Nick Lee, Woncheol Sanders, Nocona Kioupakis, Emmanouil Applied Physics Program University of Michigan Ann ArborMI48109 United States Department of Materials Science and Engineering University of Michigan Ann ArborMI48109 United States Department of Electrical Engineering and Computer Science University of Michigan Ann ArborMI48109 United States

Alloy scattering in random AlGaN alloys drastically reduces the electron mobility and therefore the power-electronics figure of merit. As a result, Al compositions greater than 75% are required to obtain even a two-fold increase of the Baliga figure of merit compared to GaN. However, beyond approximately 80% Al composition, donors in AlGaN undergo the DX transition which makes impurity doping increasingly more difficult. Moreover, the contact resistance increases exponentially with increasing Al content, and integration with dielectrics becomes difficult due to the upward shift of the conduction band. Atomically thin superlattices of AlN and GaN, also known as digital alloys, are known to grow experimentally under appropriate growth conditions. These chemically ordered nanostructures could offer significantly enhanced figure of merit compared to their random-alloy counterparts due to the absence of alloy scattering, as well as better integration with contact metals and dielectrics. In this work, we investigate the electronic structure and phonon-limited electron mobility of atomically thin AlN/GaN digital-alloy superlattices using first-principles calculations based on density-functional and many-body perturbation theory. The band gap of the atomically thin superlattices reaches 4.8 eV, and the in-plane (out-of-plane) mobility is 369 (452) cm2 V-1 s-1. Using the modified Baliga figure of merit that accounts for the dopant ionization energy, we demonstrate that atomically thin AlN/GaN superlattices with a monolayer sublattice periodicity have the highest modified Baliga figure of merit among several technologically relevant ultra-wide band-gap materials, including random AlGaN, β-Ga2O3, cBN, and diamond. Copyright © 2022, The Authors. All rights reserved.

关键词： Aluminum gallium nitride

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Low latency optical-based mode tracking with machine learning deployed on FPGAs on a tokamak

arXiv

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arXiv 2023年

作者： Wei, Yumou Forelli, Ryan F. Hansen, Chris Levesque, Jeffrey P. Tran, Nhan Agar, Joshua C. Di Guglielmo, Giuseppe Mauel, Michael E. Navratil, Gerald A. Department of Applied Physics and Applied Mathematics Columbia University New YorkNY10027 United States Real-time Processing Systems Division Fermi National Accelerator Laboratory BataviaIL60510 United States Department of Electrical and Computer Engineering Lehigh University BethlehemPA18015 United States Department of Electrical and Computer Engineering Northwestern University EvanstonIL60208 United States Department of Mechanical Engineering and Mechanics Drexel University PhiladelphiaPA19104 United States Microelectronics Division Fermi National Accelerator Laboratory BataviaIL60510 United States

Active feedback control in magnetic confinement fusion devices is desirable to mitigate plasma instabilities and enable robust operation. Optical high-speed cameras provide a powerful, non-invasive diagnostic and can be suitable for these applications. In this study, we process high-speed camera data, at rates exceeding 100 kfps, on in situ field-programmable gate array (FPGA) hardware to track magnetohydrodynamic (MHD) mode evolution and generate control signals in real-time. Our system utilizes a convolutional neural network (CNN) model which predicts the n=1 MHD mode amplitude and phase using camera images with better accuracy than other tested non-deep-learning-based methods. By implementing this model directly within the standard FPGA readout hardware of the high-speed camera diagnostic, our mode tracking system achieves a total trigger-to-output latency of 17.6 µs and a throughput of up to 120 kfps. This study at the High Beta Tokamak-Extended Pulse (HBT-EP) experiment demonstrates an FPGA-based high-speed camera data acquisition and processing system, enabling application in real-time machine-learning-based tokamak diagnostic and control as well as potential applications in other scientific domains. Copyright © 2023, The Authors. All rights reserved.

关键词： Tokamak devices

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High-Q unidirectional polarization singularities

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Physical Review applied 2025年第5期23卷 054020-054020页

作者： Chuanlin Li Wenhao Wang Jianfeng Chen Mengqi Liu Aobo Ren Cheng-Wei Qiu Hongxing Xu Zhiming Wang Jiang Wu Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of China Chengdu 610054 China Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University Singapore 637371 Singapore Centre for Disruptive Photonic Technologies The Photonics Institute Nanyang Technological University Singapore 637371 Singapore Department of Electrical and Computer Engineering National University of Singapore Singapore 117583 Singapore Institute of Engineering Thermophysics School of Mechanical Engineering Shanghai Jiao Tong University Shanghai 200240 China School of Physics and Technology Center for Nanoscience and Nanotechnology and Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education Wuhan University Wuhan 430072 China

Unidirectional guided resonances (UGRs), which are eigenstates that radiate exclusively in a single channel, are promising for advancing diverse photonic devices. However, existing approaches face an inherent trade-off between achieving high-Q factors and maximizing the radiation-asymmetry ratios. To address this challenge, we propose a scheme that exploits both out-of-plane and in-plane couplings to generate bound states in the continuum with precise radial and rotational control in momentum space. This approach effectively decouples the Q factors of UGRs from their radiation-asymmetry ratios. As a result, we achieve UGRs with Q factors exceeding 104, which is 1–2 orders of magnitude higher than traditional UGRs. Furthermore, we demonstrate the ability to reverse the emission direction of these UGRs, leading to a broad range of radiation-asymmetry ratios from −53 to 55 dB. We further validate the practical realization of high-Q UGRs using a silicon-on-silica system. Our findings provide a versatile method for generating high-Q UGRs, offering alternative pathways for innovations in nonlinear optics, light-matter interactions, and advanced optoelectronic applications.

关键词： Nonlinear optics

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