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arXiv 2023年

作者： Sala, Luca Valentini, Milena Biffi, Veronica Dolag, Klaus Universitäts-Sternwarte Fakultät für Physik Ludwig-Maximilians-Universität München Scheinerstr. 1 MünchenD-81679 Germany Astronomy Unit Department of Physics University of Trieste via Tiepolo 11 TriesteI-34131 Italy INAF – Osservatorio Astronomico di Trieste via Tiepolo 11 TriesteI-34131 Italy ICSC - Italian Research Center on High Performance Computing Big Data and Quantum Computing Italy Max-Planck-Institut für Astrophysik Karl-Schwarzschild-Str. 1 GarchingD-85741 Germany

Context. Mass and spin of massive black holes (BHs) at the centre of galaxies evolve due to gas accretion and mergers with other BHs. Besides affecting e.g. the evolution of relativistic jets, the BH spin determines the efficiency with which the BH radiates energy. Aims. Using cosmological, hydrodynamical simulations, we investigate the evolution of the BH spin across cosmic time and its role in controlling the joint growth of supermassive BHs and their host galaxies. Methods. We implement a sub-resolution prescription that models the BH spin, accounting for both BH coalescence and misaligned accretion through a geometrically thin, optically thick disc. We investigate how BH spin evolves in two idealised setups, in zoomed-in simulations, and in a cosmological volume. The latter simulation allows us to retrieve statistically robust results as for the evolution and distribution of BH spins as a function of BH properties. Results. We find that BHs with MBH 2 × 107 M☉ grow through gas accretion, occurring mostly in a coherent fashion that favours spin-up. Above MBH 2 × 107 M☉ the gas angular momentum directions of subsequent accretion episodes are often uncorrelated with each other. The probability of counter-rotating accretion and hence spin-down increases with BH mass. In the latter mass regime, BH coalescence plays an important role. The spin magnitude displays a wide variety of histories, depending on the dynamical state of the gas feeding the BH and the relative contribution of mergers and gas accretion. As a result of their combined effect, we observe a broad range of values of the spin magnitude at the high-mass end. Reorientation of the BH spin direction occurs on short timescales ( 10 Myr) only during highly-accreting phases (fEdd 0.1). Our predictions for the distributions of BH spin and spin-dependent radiative efficiency as a function of BH mass are in very good agreement with observations. © 2023, CC BY.

关键词： Numerical methods

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One-shot video-based person re-identification with variance subsampling algorithm

One-shot video-based person re-identification with variance ...

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作者： Zhao, Jing Yang, Wenjing Yang, Mingliang Huang, Wanrong Yang, Qiong Zhang, Hongguang Institute for Quantum Information & State Key Laboratory of High Performance Computing College of Computer National University of Defense Technology ChangshaHunan410073 China Artificial Intelligence Research Center National Innovation Institute of Defense Technology Beijing China

Previous works propose the distance-based sampling for unlabeled datapoints to address the few-shot person re-identification task, however, many selected samples may be assigned with wrong labels due to poor feature quality in these works, which negatively affects the learning procedure. In this article, we propose a novel sampling strategy to improve the quality of assigned pseudo-labels, thus promoting the final performance. To illustrate, we first propose the concept of variance confidence to measure the credibility of pseudo-labels, then we apply a novel variance subsampling algorithm to improve the accuracy of the selected sample labels. Our method combines distance confidence and variance confidence as a two-round sampling criterion. Meanwhile, a variation decay strategy is used in our sampling process in combination with the actual distribution of features. We evaluate our approach on two publicly available datasets, MARS and DukeMTMC-VideoReID, and achieve state-of-the-art one-shot performance. © 2020 John Wiley & Sons, Ltd.

关键词： Computer vision

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From few to many maps: A fast map-level emulator for extreme augmentation of CMB systematics datasets

arXiv

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arXiv 2025年

作者： Campeti, P. Delouis, J.-M. Pagano, L. Allys, E. Lattanzi, M. Gerbino, M. INFN Sezione di Ferrara Via Saragat 1 Ferrara44122 Italy ICSC Centro Nazionale "High Performance Computing Big Data and Quantum Computing" Univ. Brest CNRS Ifremer IRD Brest29200 France Dipartimento di Fisica e Scienze della Terra Università degli Studi di Ferrara via Saragat 1 FerraraI-44122 Italy Institut d’Astrophysique Spatiale CNRS Univ. Paris-Sud Université Paris-Saclay Bât. 121 Orsay91405 cedex France Laboratoire de Physique de l’Ecole Normale Supérieure ENS Univ. PSL CNRS Sorbonne Univ. Univ. Paris Cité Paris75005 France

We introduce a novel, fast, and efficient generative model built upon scattering covariances, the most recent iteration of the scattering transforms statistics. This model is designed to augment by several orders of magnitude the number of map simulations in datasets of computationally expensive Cosmic Microwave Background (CMB) instrumental systematics simulations, including their non-Gaussian and inhomogeneous features. Unlike conventional neural network-based algorithms, this generative model requires only a minimal number of training samples, making it highly compatible with the computational constraints of typical CMB simulation campaigns. While our primary focus is on spherical data, the framework is inherently versatile and readily applicable to 1D and 2D planar data, leveraging the localized nature of scattering statistics. We validate the method using realistic simulations of CMB systematics, which are particularly challenging to emulate, and perform extensive statistical tests to confirm its ability to produce new statistically independent approximate realizations. Remarkably, even when trained on as few as 10 simulations, the emulator closely reproduces key summary statistics—including the angular power spectrum, scattering coefficients, and Minkowski functionals—and provides pixel covariance estimates with substantially reduced sample noise compared to those obtained without augmentation. The proposed approach has the potential to shift the paradigm in simulation campaign design. Instead of producing large numbers of low- or medium-accuracy simulations, future pipelines can focus on generating a few high-accuracy simulations that are then efficiently augmented using such generative model. This promises significant benefits not only for current and forthcoming cosmological surveys such as Planck, LiteBIRD, Simons Observatory, CMB-S4, Euclid and Rubin-LSST, but also for diverse fields including oceanography and climate science. We make both the general fra

关键词： Cosmology

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Systematic bias in dark siren statistical methods and its impact on Hubble constant measurement

arXiv

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arXiv 2025年

作者： Alfradique, Viviane Bom, Clécio R. Castro, Tiago Centro Brasileiro de Pesquisas Físicas Rua Dr. Xavier Sigaud 150 RJ Rio de Janeiro22290-180 Brazil Centro Federal de Educação Tecnológica Celso Suckow da Fonseca Rodovia Márcio Covas lote J2 quadra J Itaguaí Brazil INAF Osservatorio Astronomico di Trieste via Tiepolo 11 TriesteI-34131 Italy INFN Sezione di Trieste TriesteI-34100 Italy IFPU Institute for Fundamental Physics of the Universe via Beirut 2 Trieste34151 Italy ICSC - Centro Nazionale di Ricerca in High Performance Computing Big Data e Quantum Computing Via Magnanelli 2 Bologna Italy

The advent of the multimessenger cosmology marked by the detection of GW170817, gravitational waves (GWs) from compact objects at cosmological distances demonstrated Standard Sirens as a relevant cosmological probe. In the absence of an electromagnetic counterpart identification, GWs carry valuable information through the dark siren approach, where the source redshift is estimated using galaxy catalogs of potential hosts within the localization volume. However, the dark siren analysis can be affected by galaxy catalog incompleteness at the limits of gravitational-wave detectability, potentially introducing biases in the constraints on cosmological parameters. Focusing on GWs from binary black holes (BBH) detected by the LIGO, Virgo, and KAGRA (LVK) collaboration, we explore the possible systematic biases in the measurement of the Hubble constant (H0). These biases may arise from (1) the incompleteness of catalogs due to the apparent magnitude thresholds of optical telescope sensitivity, and (2) the use of incorrect weighting schemes (e.g., using star formation or stellar mass as tracers of the host galaxy) for each potential host. We found that an unbiased estimate of H0 can be obtained when the corrected weighting scheme is applied to a complete or volume-limited catalog. The results using stellar mass as a tracer indicate that a percent-level measurement of H0, with a precision of approximately 3%, can be achieved with 100 binary black hole detections by the LVK at O4 and O5 sensitivity. The O5 run provides a slight improvement, reducing the H0 uncertainty by 0.07 km/s/Mpc compared to the O4-like configuration. This precision is achievable by using a complete galaxy catalog that covers the 90% of the localisation probability (A90%) for each GW detection, with A90% 2. The H0 precision increases to approximately 6% when it is assumed that every galaxy has an equal probability of being the host. © 2025, CC BY.

关键词： Cosmology

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Bayesian evidence estimation from posterior samples with normalizing flows

arXiv

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arXiv 2024年

作者： Srinivasan, Rahul Crisostomi, Marco Trotta, Roberto Barausse, Enrico Breschi, Matteo SISSA Via Bonomea 265 Trieste34136 Italy INFN Sezione di Trieste Trieste34149 Italy IFPU - Institute for Fundamental Physics of the Universe Via Beirut 2 Trieste34014 Italy TAPIR Division of Physics Mathematics and Astronomy California Institute of Technology PasadenaCA91125 United States Dipartimento di Fisica Università di Pisa Largo Bruno Pontecorvo 3 Pisa56127 Italy Department of Physics Imperial College London Blackett Lab Prince Consort Rd LondonSW7 2AZ United Kingdom Italian Research Center on High Performance Computing Big Data and Quantum Computing 13 Via Magnanelli 2 40033 Italy

We propose a novel method (floZ), based on normalizing flows, to estimate the Bayesian evidence (and its numerical uncertainty) from a pre-existing set of samples drawn from the unnormalized posterior distribution. We validate it on distributions whose evidence is known analytically, up to 15 parameter space dimensions, and compare with two state-of-the-art techniques for estimating the evidence: nested sampling (which computes the evidence as its main target) and a k-nearest-neighbors technique that produces evidence estimates from posterior samples. Provided representative samples from the target posterior are available, our method is more robust to posterior distributions with sharp features, especially in higher dimensions. For a simple multivariate Gaussian, we demonstrate its accuracy for up to 200 dimensions with 105 posterior samples. floZ has wide applicability, e.g., to estimate evidence from variational inference, Markov Chain Monte Carlo samples, or any other method that delivers samples and their likelihood from the unnormalized posterior density. As a physical application, we use floZ to compute the Bayes factor for the presence of the first overtone in the ringdown signal of the gravitational wave data of GW150914, finding good agreement with nested sampling. Copyright © 2024, The Authors. All rights reserved.

关键词： Markov chains

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Impact of vegetation albedo on the habitability of Earth-like exoplanets

arXiv

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arXiv 2024年

作者： Bisesi, Erica Murante, Giuseppe Provenzale, Antonello Biasiotti, Lorenzo von Hardenberg, Jost Ivanovski, Stavro Maris, Michele Monai, Sergio Silva, Laura Simonetti, Paolo Vladilo, Giovanni INAF − Astronomical Observatory of Trieste Via G. Tiepolo 11 Trieste34143 Italy CNR − Institute of Geosciences and Earth Resources via G. Moruzzi 1 Pisa56124 Italy Institute for Fundamental Physics of the Universe Via Beirut 2 Trieste34151 Italy ICSC − National Research Center in High Performance Computing Big Data e Quantum Computing Via Magnanelli 2 BO Casalecchio di Reno40033 Italy University of Trieste Piazzale Europa 1 Trieste34127 Italy Polytechnic University of Turin − DIATI Corso Duca degli Abruzzi 24 Turin10129 Italy CNR − Institute of Atmospheric Science and Climate Corso Fiume 4 Turin10133 Italy

Vegetation can modify the planetary surface albedo via the Charney mechanism, as plants are usually darker than the bare surface of the continents. We updated ESTM (Earth-like Surface Temperature Model) to incorporate the presence, distribution and evolution of two dynamically competing vegetation types that resemble grasslands and trees (the latter in the double stages of life: adults and seedlings). The newly developed model was applied to estimate how the climate-vegetation system reaches equilibrium across different rocky planetary configurations, and to assess its impact on temperature and habitability. With respect to a world with bare granite continents, the effect of vegetation-albedo feedback is to increase the average surface temperature. Since grasses and trees exhibit different albedos, they affect temperature to different degrees. The ultimate impact on climate depends on the outcome of the competition between these vegetation types. The change in albedo due to vegetation extends the habitable zone and enhances the overall planetary habitability beyond its traditional outer edge. This effect is especially relevant for planets that have a larger extension of continents than Earth. For Earth, the semi-major axis d = 1.04 UA represents the turning point where vegetation enhances habitability from h = 0.0 to h = 0.485 (in the grass-dominance case), to h = 0.584 (in the case of coexistence between grasses and trees), and to h = 0.612 (in the tree-dominance case). This illustrates the transition from a snowball state to a planet with intermediate habitability at the outer edge of the circumstellar habitability zone. Copyright © 2024, The Authors. All rights reserved.

关键词： Vegetation

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MotionTrack: Learning Motion Predictor for Multiple Object Tracking

arXiv

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arXiv 2023年

作者： Xiao, Changcheng Cao, Qiong Zhong, Yujie Lan, Long Zhang, Xiang Luo, Zhigang Tao, Dacheng School of Computer Science National University of Defense Technology Hunan Changsha410073 China JD Explore Academy Beijing102628 China Meituan Inc. Beijing100000 China Laboratory of Digitizing Software for Frontier Equipment National University of Defense Technology Hunan Changsha410073 China Institute for Quantum State Key Laboratory of High Performance Computing National University of Defense Technology Hunan Changsha410073 China

Significant progress has been achieved in multi-object tracking (MOT) through the evolution of detection and re-identification (ReID) techniques. Despite these advancements, accurately tracking objects in scenarios with homogeneous appearance and heterogeneous motion remains a challenge. This challenge arises from two main factors: the insufficient discriminability of ReID features and the predominant utilization of linear motion models in MOT. In this context, we introduce a novel motion-based tracker, MotionTrack, centered around a learnable motion predictor that relies solely on object trajectory information. This predictor comprehensively integrates two levels of granularity in motion features to enhance the modeling of temporal dynamics and facilitate precise future motion prediction for individual objects. Specifically, the proposed approach adopts a self-attention mechanism to capture token-level information and a Dynamic MLP layer to model channel-level features. MotionTrack is a simple, online tracking approach. Our experimental results demonstrate that MotionTrack yields state-of-the-art performance on datasets such as Dancetrack and SportsMOT, characterized by highly complex object motion. Copyright © 2023, The Authors. All rights reserved.

关键词： Motion estimation

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quantum memory assisted entangled state verification with local measurements

arXiv

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arXiv 2023年

作者： Chen, Siyuan Xie, Wei Xu, Ping Wang, Kun Hefei National Research Center for Physical Sciences Microscale School of Physical Sciences University of Science and Technology of China Hefei230026 China College of Physics Jilin University Changchun130012 China School of Computer Science and Technology University of Science and Technology of China Hefei230027 China Institute for Quantum Information State Key Laboratory of High Performance Computing College of Computer Science and Technology National University of Defense Technology Changsha410073 China

We consider the quantum memory assisted quantum state verification task, where an adversary prepare independent multipartite entangled states and send to the local verifiers, who then store several copies in the quantum memory and measure them collectively to make decision. We establish an exact analytic formula for optimizing two-copy state verification, where the verifiers store two copies, and give a globally optimal two-copy strategy for multi-qubit graph states involving only Bell measurements. When the verifiers can store arbitrarily many copies, we present a dimension expansion technique that designs efficient verification strategies for this case, showcasing its application to efficiently verifying GHZ-like states. These strategies become increasingly advantageous with growing memory resources, ultimately approaching the theoretical limit of efficiency. Our findings demonstrate that quantum memories enhance state verification efficiency, sheding light on error-resistant strategies and practical applications of large-scale quantum memory-assisted verification. © 2023, CC BY.

关键词： quantum entanglement

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Universal conservation laws of the wave-particleentanglement triad:theory and experiment

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Light(Science & Applications) 2025年第3期14卷 861-868页

作者： Ziheng Ding Yaohao Deng Shao-Ming Fei Si-Qi Zhou Xiaojiong Chen Ziwen Rui Zhihao Ma Yunlong Xiao Jianwei Wang School of Mathematical Sciences MOE-LSCShanghai Jiao Tong UniversityShanghai 200240China State Key Laboratory for Mesoscopic Physics School of PhysicsPeking UniversityBejing 100871China Bejing Academy of Quantum Information Sciences Beijing 100871China School of Mathematical Sciences Capital Normal UniversityBeijing 100048China Max Planck Institute for Mathematics in the Sciences Leipzig 04103Germany Department of Physics and Astronomy Stony Brook UniversityNew YorkNY11794-3800USA Shanghai Seres Information Technology Co. LtdShanghai 200040China shenzhen Institute for Quantum Science and Engineering Southern University of Science and TechnologyShenzhen 518055China A*STAR Quantum Innovation Centre(Q.InC) Agency for ScienceTechnology and Research(A*STAR)2Fusionopolis WayInnovis\#08-03Singapore138634Republic of Singapore institute of High Performance Computing(IHPC) Agency for ScienceTechnology and Research(A*STAR)1 Fusionopolis WayConnexis\#16-16Singapore 138632Republic of Singapore

When observed,a quantum system exhibits either wave-like or particle-like properties,depending on how it is ***,this duality is affected by the entanglement of the system with its quantum memory,raising a fundamental question:how are wave-particle duality and entanglement related?Here,we broaden the scope of wave-particle duality to include entanglement,introduce universal conservation laws for the wave-particle-entanglement triad,and perform demonstrations on silicon-integrated nanophotonic quantum *** experiments not only mark the first confirmation of universal conservation laws but also highlight the potential of integrated photonics for exploring complex quantum phenomena in high-dimensional systems.

关键词： high dimensional systems universal conservation laws entanglement nanophotonic quantum chips quantum systems wave particle duality quantum system

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Resilience of quantum Key Distribution Source Against Laser-Damage Attack by a Variety of Lasers

Resilience of Quantum Key Distribution Source Against Laser-...

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Conference on Lasers and Electro-Optics Europe (CLEO EUROPE)

作者： Daria Ruzhitskaya Irina Zhluktova Anastasiya Ponosova Daniil Trefilov Poompong Chaiwongkhot Anqi Huang Vladimir Kamynin Vadim Makarov Russian Quantum Center Skolkovo Moscow Russia NTI Center for Quantum Communications National University of Science and Technology MISiS Moscow Russia Prokhorov General Physics Institute of Russian Academy of Sciences Moscow Russia MIREA - Russian Technological University Moscow Russia Vigo Quantum Communication Center University of Vigo Vigo Spain Department of Physics Faculty of Science Mahidol University Bangkok Thailand State Key Laboratory of High Performance Computing Institute for Quantum Information College of Computer Science and Technology National University of Defense Technology Changsha China Shanghai Branch National Laboratory for Physical Sciences at Microscale CAS Center for Excellence in Quantum Information University of Science and Technology of China Shanghai People's Republic of China

ISBN: (纸本)9798350345995

quantum key distribution (QKD) systems provide quantum-safe key exchange. Therefore, complete security analysis of implementations of QKD protocols is in the focus of interest of a worldwide information-security community. For today, a number of QKD loopholes are closed by countermeasures, which are also considered in emerging QKD security evaluation and certification [1]–[3]. However, new threats to practical QKD implementations are still found, such as the laser-damage attack, which is a powerful hacking strategy. In investigations, CW laser radiation is most often used, but in contrast to it, the interaction of pulsed laser radiation with optical materials may lead to a wide range of effects, like nonlinear effects, dielectric breakdown, etc.

关键词： Fiber optic components high power lasers Nonlinear effects Optical materials quantum key distribution quantum key distribution networks

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