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Optically-Sampled Superconducting-Nanostrip Photon-Number Resolving Detector for Non-Classical Quantum State Generation

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arXiv 2024年

作者： Endo, Mamoru Takahashi, Kazuma Nomura, Takefumi Sonoyama, Tatsuki Yabuno, Masahiro Miki, Shigehito Terai, Hirotaka Kashiwazaki, Takahiro Inoue, Asuka Umeki, Takeshi 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 Advanced ICT Research Institute National Institute of Information and Communications Technology 588-2 Iwaoka Nishi Kobe651-2492 Japan NTT Device Technology Labs NTT Corporation 3-1 Morinosato Wakamiya Kanagawa Atsugi243-0198 Japan Department of Electrical and Computer Engineering University of Massachusetts Amherst AmherstMA01003 United States Department of Physics University of Massachusetts Amherst AmherstMA01003 United States College of Information and Computer Science University of Massachusetts Amherst AmherstMA01003 United States

Photon number-resolving detectors (PNRDs) are the ultimate optical sensors. Superconducting-nanostrip photon detectors (SNSPDs), traditionally known as ON-OFF detectors, have recently been found to have photon number resolving capability without multiplexing. This discovery positions them to become true PNRDs. However, their practical use is limited by the need to precisely detect tiny signal differences with low signal-to-noise ratios within sub-nanosecond time frames. We overcome this challenge using optical sampling with a dual-output Mach Zehnder modulator (DO-MZM) and ultra-short pulsed laser. By adjusting the DO-MZM’s bias voltage to nearly balance the outputs, this method enables sensitive detection of picosecond-order signal differences, achieving a temporal resolution of 1.9 ps and facilitating real-time photon number resolution. We applied this method to produce various non-classical quantum states, enhancing their non-classicality through photon number resolution. This advancement marks a significant shift from principle verification to practical application for SNSPD-type PNRDs in diverse quantum optics fields. Copyright © 2024, The Authors. All rights reserved.

关键词： Quantum optics

GRB 220408B: A Three-Episode Burst from a Precessing Jet

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arXiv 2023年

作者： Zhang, Zijian Yin, Yihan Wang, Chenyu Wang, Xiangyu Ivy Yang, Jun Meng, Yan-Zhi Liu, Zi-Ke Chen, Guo-Yin Fu, Xiaoping Gao, Huaizhong Li, Sihao Liu, Yihui Long, Xiangyun Ma, Yong-Chang Pan, Xiaofan Sun, Yuanze Wu, Wei Yang, Zirui Ye, Zhizhen Yu, Xiaoyu Zhao, Shuheng Zheng, Xutao Zhou, Tao Tang, Qing-Wen Yan, Qiurong Zhou, Rong Wang, Zhonghai Feng, Hua Zeng, Ming Zhang, Bin-Bin School of Astronomy and Space Science Nanjing University Nanjing210093 China School of Physics Nanjing University Nanjing210093 China Department of Astronomy Tsinghua University Beijing100084 China Key Laboratory of Modern Astronomy and Astrophysics [Nanjing University Ministry of Education China School of Information Engineering Nanchang University Nanchang330031 China Department of Engineering Physics Tsinghua University Beijing100084 China Department of Health Physics China Institute for Radiation Protection Taiyuan300000 China Key Laboratory of Radiation Physics and Technology of Ministry of Education College of Physics of Sichuan University Chengdu China School of Artificial Intelligence Nanjing University Nanjing210093 China Ministry of Education Beijing100084 China Department of Computer Science and Technology Nanjing University Nanjing210093 China School of Chemistry and Chemical Engineering Nanjing University Nanjing210093 China College of Engineering and Applied Sciences Nanjing University Nanjing210093 China Department of Physics School of Physics and Materials Science Nanchang University Nanchang330031 China Purple Mountain Observatory Chinese Academy of Sciences Nanjing210023 China

Jet precession has previously been proposed to explain the apparently repeating features in the light curves of a few gamma-ray bursts (GRBs). In this Letter, we further apply the precession model to a bright GRB 220408B by examining both its temporal and spectral consistency with the predictions of the model. As one of the recently confirmed GRBs observed by our GRID CubeSat mission, GRB 220408B is noteworthy as it exhibits three apparently similar emission episodes. Furthermore, the similarities are reinforced by their strong temporal correlations and similar features in terms of spectral evolution and spectral lags. Our analysis demonstrates that these features can be well explained by the modulated emission of a Fast-Rise-Exponential-Decay (FRED) shape light curve intrinsically produced by a precessing jet with a precession period of 18.4 ± 0.2 seconds, a nutation period of 11.1 ± 0.2 seconds and viewed off-axis. This study provides a straightforward explanation for the complex yet similar multi-episode GRB light curves. Copyright © 2023, The Authors. All rights reserved.

关键词： Gamma rays

Testing External Polymer Insulation Materials for Resistance to Electrical Tracing and Degradation Using the Inclined Plane Method

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Testing External Polymer Insulation Materials for Resistance...

International Conference on Contemporary Computing and Informatics (IC3I)

作者： Ankur Kumar Gupta Diwakar Padalia Arun Gangwar Sandeep Sharma Sachin K Kamble Sonali Prashant Bhoite School of Computer Science and Applications IIMT University Meerut India Department of Physics School of Basic& Applied Sciences K. R. Mangalam University Gurugram India Department of Electrical Engineering Invertis University Bareilly India School of Electronic and Electrical Engineering Dev Bhoomi Uttarakhand University Uttarakhand India Design Dept Terna Engineering College Navi Mumbai India Vishwakarma Institute of Information Technology Pune India

An important step in creating outdoor insulators is to assess the polymeric housing materials' resistance to weathering and electrical tracking. The terms “erosion” and “tracking” refer to the weight loss of the housing material and the production of a surface carbonaceous trail, respectively. With the help of the common tracking and erosion tests, composites can only be ranked relative to one another in terms of their tracking and erosion resistance, which makes it impossible to quantify these properties in absolute terms. Failure due to the track was a major issue during the early stages of the usage of organic insulating materials. The introduction of tracking-resistant composites with significant inorganic filler content has increased the importance of erosion.

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N-way parametric frequency beamsplitter for quantum photonics

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Physical Review Research 2025年第2期7卷 023108-023108页

作者： Richard Oliver Miri Blau Chaitali Joshi Xingchen Ji Ricardo Gutiérrez-Jáuregui Ana Asenjo-Garcia Michal Lipson Alexander L. Gaeta Department of Applied Physics and Applied Mathematics Columbia University 500 West 120th Street New York New York 10027 USA Present address: Google Quantum AI Santa Barbara CA 93111 USA. Department of Electrical Engineering Columbia University 500 West 120th Street New York New York 10027 USA Present address: John Hopcroft Center for Computer Science School of Electronic Information and Electrical Engineering Shanghai Jiao Tong University Shanghai 200240 China. Department of Physics Columbia University 538 West 120th Street New York New York 10027 USA Departamento de Física Cuántica y Fotónica Instituto de Física Universidad Nacional Autónoma de México Ciudad de México 04510 Mexico

Optical networks are the leading platform for the transfer of information due to their low loss and ability to scale to many information channels using optical frequency modes. To fully leverage the quantum properties of light in this platform, it is desired to manipulate higher-dimensional superpositions by orchestrating linear, beamsplitter-type interactions between several channels simultaneously. We propose a method of achieving simultaneous, all-to-all coupling between N optical frequency modes via N-way Bragg-scattering four-wave mixing. By exploiting the frequency degree of freedom, additional modes can be multiplexed in an interaction medium of fixed volume and loss while avoiding the introduction of excess noise. We generalize the theory of the frequency-encoded two-mode interaction to N modes under this four-wave-mixing approach, finding that arbitrary unitary transformations are possible through successive four-wave-mixing pump configurations. We experimentally verify the quantum nature of this scheme by demonstrating three-way multiphoton interference. Two input photons are shared among three frequency modes and display interference differing from that of two classical (coherent-state) inputs. These results show the potential of our approach for the scalability of photonic quantum information processing to general N-mode systems in the frequency domain.

关键词： Four wave mixing

Depression and Anxiety on Twitter During the COVID-19 Stay-At-Home Period in 7 Major U.S. Cities

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AJPM Focus 2023年第1期2卷 100062-100062页

作者： Levanti, Danielle Monastero, Rebecca N. Zamani, Mohammadzaman Eichstaedt, Johannes C. Giorgi, Salvatore Schwartz, H. Andrew Meliker, Jaymie R. Undergraduate Studies Cornell University Ithaca NY United States Renaissance School of Medicine Stony Brook University Stony Brook NY United States Department of Computer Science College of Engineering and Applied Sciences Stony Brook University Stony Brook NY United States Department of Psychology School of Humanities and Sciences Stanford University Palo Alto CA United States Department of Computer and Information Science University of Pennsylvania Philadelphia PA United States Program in Public Health Department of Family Population & Preventive Medicine Renaissance School of Medicine Stony Brook University Stony Brook NY United States

Introduction: Although surveys are a well-established instrument to capture the population prevalence of mental health at a moment in time, public Twitter is a continuously available data source that can provide a broader window into population mental health. We characterized the relationship between COVID-19 case counts, stay-at-home orders because of COVID-19, and anxiety and depression in 7 major U.S. cities utilizing Twitter data. Methods: We collected 18 million Tweets from January to September 2019 (baseline) and 2020 from 7 U.S. cities with large populations and varied COVID-19 response protocols: Atlanta, Chicago, Houston, Los Angeles, Miami, New York, and Phoenix. We applied machine learning‒based language prediction models for depression and anxiety validated in previous work with Twitter data. As an alternative public big data source, we explored Google Trends data using search query frequencies. A qualitative evaluation of trends is presented. Results: Twitter depression and anxiety scores were consistently elevated above their 2019 baselines across all the 7 locations. Twitter depression scores increased during the early phase of the pandemic, with a peak in early summer and a subsequent decline in late summer. The pattern of depression trends was aligned with national COVID-19 case trends rather than with trends in individual states. Anxiety was consistently and steadily elevated throughout the pandemic. Google search trends data showed noisy and inconsistent results. Conclusions: Our study shows the feasibility of using Twitter to capture trends of depression and anxiety during the COVID-19 public health crisis and suggests that social media data can supplement survey data to monitor long-term mental health trends. © 2022 The Author(s)

关键词： coronavirus mental health Social media stay-at-home order

Work fluctuations due to partial thermalizations in two-level systems

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arXiv 2021年

作者： Quadeer, Maria Korzekwa, Kamil Tomamichel, Marco Centre for Quantum Software and Information School of Computer Science University of Technology Sydney NSW2007 Australia Faculty of Physics Astronomy and Applied Computer Science Jagiellonian University Kraków30-348 Poland Department of Electrical and Computer Engineering Centre for Quantum Technologies National University of Singapore Singapore119077 Singapore

We study work extraction processes mediated by finite-time interactions with an ambient bath—partial thermalizations—as continuous time Markov processes for two-level systems. Such a stochastic process results in fluctuations in the amount of work that can be extracted and is characterized by the rate at which the system parameters are driven in addition to the rate of thermalization with the bath. We analyze the distribution of work for the case where the energy gap of a two-level system is driven at a constant rate. We derive analytic expressions for average work and lower bound for the variance of work showing that such processes cannot be fluctuation-free in general. We also observe that an upper bound for the Monte Carlo estimate of the variance of work can be obtained using Jarzynski’s fluctuation-dissipation relation for systems initially in equilibrium. Finally, we analyse work extraction cycles by modifying the Carnot cycle, incorporating processes involving partial thermalizations and obtain efficiency at maximum power for such finite-time work extraction cycles under different sets of constraints. Copyright © 2021, The Authors. All rights reserved.

关键词： Carnot cycle

Performance of NEMA characteristics of Modular J-PET

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Performance of NEMA characteristics of Modular J-PET

IEEE Symposium on Nuclear science (NSS/MIC)

作者： F. Tayefi Ardebili S. Niedźwiecki J. Baran E. Beyene D. Borys K. Brzezinski N. Chug A. Coussat C. Curceanu E. Czerwinski M. Dadgar K. Dulski K. Eliyan J. Gajewski A. Gajos B. Hiesmayr A. Jedruszczak K. Kacprzak M. Kajetanowicz T. Kaplanoglu L. Kapłon K. Klimaszewski G. Korcyl T. Kozik W. Krzemien D. Kumar G. Lapkiewicz W. Migdal S. Moyo W. Mryka S. Parzych E. Pérez del Río L. Raczyński S. Sharma S. Shivani R. Shopa M. Skurzok P. Tanty K. Tayefi Ardebili W. Wislicki E. Stępień P. Moskal Faculty of Physics Astronomy and Applied Computer Science Jagiellonian University Krakow Poland Center for Theranostics Jagiellonian University Krakow Poland Total-Body Jagiellonian-PET Laboratory Jagiellonian University Krakow Poland Faculty of Physics University of Vienna Vienna Austria Department of Systems Biology and Engineering Silesian University of Technology Gliwice Poland Laboratori Nazionali di Frascati INFN Frascati Italy Department of Electronics and Information Systems Ghent University Ghent Belgium Department of Complex Systems National Centre for Nuclear Research Otwock-Swierk Poland Institute of Nuclear Physics PAN IFJPAN Krakow Poland

The Modular J-PET scanner, developed by the J-PET collaboration, is a new prototype PET scanner developed based on axially arranged plastic scintillators as a large axial field of view (50cm) affordable tomograph. In this study, the performance characteristics of the scanner were evaluated according to NEMA NU2-2018 standards using Monte Carlo simulation. In order to ensure the selection of true coincidence events, certain criteria were established. Specifically, each photon emitting from a single annihilation must deposit at least 200 keV within 4 ns of a coincidence time window. The preliminary results showed that the sensitivity profile peak was 4 cps/kBq at the center of the detector, While the scatter fraction was estimated to be 39% using the single slice rebinning algorithm. Spatial resolution was estimated around 4.5 mm in the radial and tangential direction and 18 mm in the axial direction.

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Magnetic anisotropy of the van der Waals ferromagnet Cr2Ge2Te6 studied by angular-dependent x-ray magnetic circular dichroism

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Physical Review Research 2022年第1期4卷 013139-013139页

作者： M. Suzuki B. Gao G. Shibata S. Sakamoto Y. Nonaka K. Ikeda Z. Chi Y.-X. Wan T. Takeda Y. Takeda T. Koide A. Tanaka M. Kobayashi S.-W. Cheong A. Fujimori Department of Physics The University of Tokyo Bunkyo-ku Tokyo 113-0033 Japan Rutgers Center for Emergent Materials and Department of Physics and Astronomy Rutgers University Piscataway New Jersey 08854 USA Department of Applied Physics Tokyo University of Science Katsushika-ku Tokyo 125-8585 Japan Department of Electrical Engineering and Information Systems The University of Tokyo Bunkyo-ku Tokyo 113-8656 Japan Materials Sciences Research Center Japan Atomic Energy Agency (JAEA) Sayo Hyogo 679-5148 Japan Photon Factory Institute of Materials Structure Science High Energy Accelerator Research Organization Tsukuba Ibaraki 305-0801 Japan Quantum Matter Program Graduate School of Advanced Science and Engineering Hiroshima University Higashi-hiroshima 739-8530 Japan Center for Spintronics Research Network The University of Tokyo Bunkyo-ku Tokyo 113-0033 Japan Department of Applied Physics Waseda University Shinjuku-ku Tokyo 169-8555 Japan

The van der Waals ferromagnet Cr2Ge2Te6 (CGT) has a two-dimensional crystal structure where each layer is stacked through van der Waals force. We have investigated the nature of the ferromagnetism and the weak perpendicular magnetic anisotropy (PMA) of CGT by means of x-ray absorption spectroscopy and x-ray magnetic circular dichroism (XMCD) studies of CGT single crystals. The XMCD spectra at the Cr L2,3 edge for different magnetic field directions were analyzed on the basis of the cluster-model multiplet calculation. The Cr valence is confirmed to be 3+ and the orbital magnetic moment is found to be nearly quenched, as expected for the high-spin t2g3 configuration of the Cr3+ ion. A large (∼0.2 eV) trigonal crystal-field splitting of the t2g level caused by the distortion of the CrTe6 octahedron has been revealed, while the single-ion anisotropy (SIA) of the Cr atom is found to have a sign opposite to the observed PMA and too weak compared to the reported anisotropy energy. The present result suggests that anisotropic exchange coupling between the Cr atoms through the ligand Te 5p orbitals having strong spin-orbit coupling has to be invoked to explain the weak PMA of CGT, as in the case of the strong PMA of CrI3.

关键词： Electronic structure Magnetic anisotropy 2-dimensional systems Magnetic semiconductors Cluster models X-ray magnetic circular dichroism

Autonomous bootstrapping of quantum dot devices

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arXiv 2024年

作者： Zubchenko, Anton Middlebrooks, Danielle Rasmussen, Torbjørn Lausen, Lara Kuemmeth, Ferdinand Chatterjee, Anasua Zwolak, Justyna P. Center for Quantum Devices Niels Bohr Institute University of Copenhagen Copenhagen2100 Denmark QuTech and Kavli Institute of Nanoscience Delft University of Technology Delft Netherlands National Institute of Standards and Technology GaithersburgMD20899 United States Institute of Experimental and Applied Physics University of Regensburg Regensburg93040 Germany QDevil Quantum Machines Ballerup2750 Denmark Joint Center for Quantum Information and Computer Science University of Maryland College ParkMD20742 United States Department of Physics University of Maryland College ParkMD20742 United States

Semiconductor quantum dots (QDs) are a promising platform for multiple different qubit implementations, all of which are voltage controlled by programmable gate electrodes. However, as the QD arrays grow in size and complexity, tuning procedures that can fully autonomously handle the increasing number of control parameters are becoming essential for enabling scalability. We propose a bootstrapping algorithm for initializing a depletion-mode QD device in preparation for subsequent phases of tuning. During bootstrapping, the QD device functionality is validated, all gates are characterized, and the QD charge sensor is made operational. We demonstrate the bootstrapping protocol in conjunction with a coarse-tuning module, showing that the combined algorithm can efficiently and reliably take a cooled-down QD device to a desired global-state configuration in under 8 min with a success rate of 96 %. Finally, by following heuristic approaches to QD device initialization and combining the efficient ray-based measurement with the rapid radio-frequency reflectometry measurements, the proposed algorithm establishes a reference in terms of performance, reliability, and efficiency against which alternative algorithms can be benchmarked. Copyright © 2024, The Authors. All rights reserved.

关键词： Semiconductor quantum dots