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arXiv 2024年

作者： Groth, Frederick Valentini, Milena Steinwandel, Ulrich P. Vallés-Pérez, David Dolag, Klaus Universitäts-Sternwarte Fakultät für Physik Ludwig-Maximilians-Universität München Scheinerstr. 1 München81679 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 via Magnanelli 2 Casalecchio di Reno40033 Italy Center for Computational Astrophysics Flatiron Institute 162 Fifth Avenue New YorkNY10010 United States Departament d’Astronomia i Astrofísica Universitat de València C/Doctor Moliner 50 Burjassot ValènciaE-46100 Spain Max-Planck-Institut für Astrophysik Karl-Schwarzschild-Straße 1 Garching85741 Germany

Context. The amount of turbulent pressure in galaxy clusters is still debated, especially as for the impact of the dynamical state and the hydro-method used for simulations. Aims. We study the turbulent pressure fraction in the intra cluster medium of massive galaxy clusters. We aim to understand the impact of the hydrodynamical scheme, analysis method, and dynamical state on the final properties of galaxy clusters from cosmological simulations. Methods. We perform non-radiative simulations of a set of zoom-in regions of seven galaxy clusters with Meshless Finite Mass (MFM) and Smoothed Particle Hydrodynamics (SPH). We use three different analysis methods based on: (i) the deviation from hydrostatic equilibrium, (ii) the solenoidal velocity component obtained by a Helmholtz-Hodge decomposition, and (iii) the small-scale velocity obtained through a multi-scale filtering approach. We split the sample of simulated clusters into active and relaxed clusters. Results. Our simulations predict an increased turbulent pressure fraction for active compared to relaxed clusters. This is especially visible for the velocity-based methods. For these, we also find increased turbulence for the MFM simulations compared to SPH, consistent with findings from more idealized simulations. The predicted non-thermal pressure fraction varies between a few percent for relaxed clusters and ≈ 13% for active ones within the cluster center and increases towards the outskirts. No clear trend with redshift is visible. Conclusions. Our analysis quantitatively assesses the importance played by the hydrodynamical scheme and the analysis method to determine the non-thermal/turbulent pressure fraction. While our setup is relatively simple (non-radiative runs), our simulations show agreement with previous, more idealized simulations, and make a step further toward the understanding of turbulence. Copyright © 2024, The Authors. All rights reserved.

关键词： Cosmology

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Simulating the LOcal Web (SLOW) II. Properties of local galaxy clusters

arXiv

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arXiv 2024年

作者： Hernández-Martínez, Elena Dolag, Klaus Seidel, Benjamin Sorce, Jenny G. Aghanim, Nabila Pilipenko, Sergey Gottlöber, Stefan Lebeau, Théo Valentini, Milena Universitäts-Sternwarte Fakultät für Physik Ludwig-Maximilians-Universität München Scheinerstr.1 München81679 Germany Max Planck Institute for Astrophysics Karl-Schwarzschild-Str. 1 GarchingD-85741 Germany Univ. Lille CNRS Centrale Lille UMR 9189 CRIStAL LilleF-59000 France Université Paris-Saclay CNRS Institut d’Astrophysique Spatiale Orsay91405 France An der Sternwarte 16 PotsdamD-14482 Germany Astronomy Unit Department of Physics University of Trieste Via Tiepolo 11 TriesteI-34131 Italy ICSC - Italian Research Center on High Performance Computing Big Data and Quantum Computing Italy INAF Osservatorio Astronomico di Trieste Via Tiepolo 11 TriesteI-34131 Italy P.N. Lebedev Physical Institute The Russian Academy of Sciences Profsojuznaja 84/32 Moscow117997 Russia

Context. This is the second paper in a series presenting the results from a 500 ℎ−1Mpc large constrained simulation of the local Universe (SLOW). The initial conditions for this cosmological hydro-dynamical simulation are based on peculiar velocities derived from the CosmicFlows-2 catalog. The simulation follows cooling, star formation, and the evolution of super-massive black holes. This allows one to directly predict observable properties of the intracluster medium (ICM) within galaxy clusters, including X-ray luminosity, temperatures, and the Compton-y signal. Aims. Comparing the properties of observed galaxy clusters within the local Universe with the properties of their simulated counterparts enables us to assess the effectiveness of the initial condition constraints in accurately replicating the mildly nonlinear properties of the largest, collapsed objects within the simulation. Methods. Based on the combination of several, publicly available surveys we compiled a sample of galaxy clusters within the local Universe, of which we were able to cross-identify 46 of them with an associated counterpart within the SLOW simulation. We then derived the probability of the cross identification based on mass, X-ray luminosity, temperature, and Compton-y by comparing it to a random selection. Results. Our set of 46 cross-identified local Universe clusters contains the 13 most massive clusters from the Planck SZ catalog as well as 70% of clusters with M500 larger than 2 × 1014 M☉. Compared to previous constrained simulations of the local volume, we found in SLOW a much larger amount of replicated galaxy clusters, where their simulation-based mass prediction falls within the uncertainties of the observational mass estimates. Comparing the median observed and simulated masses of our cross-identified sample allows us to independently deduce a hydrostatic mass bias of (1 − b) ≈ 0.87. Conclusions. The SLOW constrained simulation of the local Universe faithfully reproduces numero

关键词： Cosmology

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Protecting fiber-optic quantum key distribution sources against light-injection attacks

arXiv

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arXiv 2022年

作者： Ponosova, Anastasiya Ruzhitskaya, Daria Chaiwongkhot, Poompong Egorov, Vladimir Makarov, Vadim Huang, Anqi Russian Quantum Center Skolkovo Moscow121205 Russia NTI Center for Quantum Communications National University of Science and Technology MISiS Moscow119049 Russia Institute for Quantum Computing University of Waterloo WaterlooONN2L 3G1 Canada Department of Physics and Astronomy University of Waterloo WaterlooONN2L 3G1 Canada Department of Physics Faculty of Science Mahidol University Bangkok10400 Thailand Bangkok10110 Thailand Leading Research Center for Quantum Internet ITMO University Birzhevaya line 14 St. Petersburg199034 Russia SMARTS-Quanttelecom LLC 6 liniya V.O. 59 St. Petersburg199178 Russia Shanghai Branch National Laboratory for Physical Sciences at Microscale CAS Center for Excellence in Quantum Information University of Science and Technology of China Shanghai201315 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

A well-protected and characterised source in a quantum key distribution system is needed for its security. Unfortunately, the source is vulnerable to light-injection attacks, such as Trojan-horse, laser-seeding, and laser-damage attacks, in which an eavesdropper actively injects bright light to hack the source unit. The hacking laser could be a high-power one that can modify properties of components via the laser-damage attack and also further help the Trojan-horse and other light-injection attacks. Here we propose a countermeasure against the light-injection attacks, consisting of an additional sacrificial component placed at the exit of the source. This component should either withstand high-power incoming light while attenuating it to a safe level that cannot modify the rest of the source, or get destroyed into a permanent high-attenuation state that breaks up the line. We demonstrate experimentally that off-the-shelf fiber-optic isolators and circulators have these desired properties, at least under attack by a continuous-wave high-power laser. Copyright © 2022, The Authors. All rights reserved.

关键词： Laser damage

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Weighing neutrinos with 21cm Intensity Mapping at the SKAO

arXiv

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arXiv 2025年

作者： Autieri, Gabriele Berti, Maria Spinelli, Marta Haridasu, Balakrishna Sandeep Viel, Matteo SISSA- International School for Advanced Studies Via Bonomea 265 Trieste34136 Italy INFN National Institute for Nuclear Physics Via Valerio 2 TriesteI-34127 Italy IFPU Institute for Fundamental Physics of the Universe via Beirut2 Trieste34151 Italy Département de Physique Théorique Center for Astroparticle Physics Université de Genève Quai E. Ansermet 24 Genève 4CH-1211 Switzerland Observatoire de la Côte d’Azur Laboratoire Lagrange Bd de l’Observatoire CS 34229 Nice06304 cedex 4 France Department of Physics and Astronomy University of the Western Cape Robert Sobukwe Road Cape Town7535 South Africa INAF Osservatorio Astronomico di Trieste Via G. B. Tiepolo 11 TriesteI-34131 Italy Italian Research Center on High Performance Computing Big Data and Quantum Computing Italy

We explore the constraining power of future 21cm intensity mapping (IM) observations at the SKAO, focusing primarily on the sum of neutrino masses, Σmν. We forecast observations of the 21cm IM auto-power spectrum as well as the 21cm IM and galaxy surveys cross-correlation power spectrum. We construct different synthetic data sets of observations for the 21cm IM observables in the redshift range 0 ν = 0.06, 0.1, 0.4 eV, in the synthetic data sets. To investigate the constraining power of the forecasted 21cm observations, we build a likelihood code that will be made publicly available upon publication. The results of the analysis, obtained through Markov Chain Monte Carlo techniques, are promising. We find that the 21cm auto-power spectrum alone could provide an upper limit on the sum of neutrino masses of Σmν ν. This result is comparable to the upper limits provided by cosmic microwave background (CMB) observations alone. When combining the 21cm auto-power spectrum synthetic data set with Planck 2018 CMB measurements, we find a tighter upper limit of Σmν ν ν Copyright © 2025, The Authors. All rights reserved.

关键词： Markov processes

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Perceptual Quality Assessment of Virtual Reality Videos in the Wild

arXiv

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arXiv 2022年

作者： Wen, Wen Li, Mu Yao, Yiru Sui, Xiangjie Zhang, Yabin Lan, Long Fang, Yuming Ma, Kede Department of Computer Science City University of Hong Kong Kowloon Hong Kong School of Computer Science and Technology Harbin Institute of Technology Guangdong Shenzhen518055 China School of Information Management Jiangxi University of Finance and Economics Jiangxi Nanchang330032 China Multimedia Lab Bytedance Inc 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

Investigating how people perceive virtual reality (VR) videos in the wild (i.e., those captured by everyday users) is a crucial and challenging task in VR-related applications due to complex *** video databases only consider synthetic distortions, assume fixed viewing conditions, and are limited in size. To overcome these shortcomings, we construct the VR Video Quality in the Wild (VRVQW) database, containing 502 user-generated videos with diverse content and distortion characteristics. Based on VRVQW, we conduct a formal psychophysical experiment to record the scanpaths and perceived quality scores from 139 participants under two different viewing conditions. We provide a thorough statistical analysis of the recordeddata, observing significantimpact of viewing conditions on both human scanpaths and perceived quality. Moreover, we develop an objective quality assessment model for VR videos based on pseudocylindrical representation and convolution. Results on the proposed VRVQW show that our method is superior to existing video quality assessment *** have made the database and code available at https://***/ limuhit/VR-Video-Quality-in-the-Wild. Index Terms-Virtual reality, panoramic videos, video quality assessment, psychophysics. Copyright © 2022, The Authors. All rights reserved.

关键词： Virtual reality

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Analysis of Video Quality Datasets via Design of Minimalistic Video Quality Models

arXiv

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arXiv 2023年

作者： Sun, Wei Wen, Wen Min, Xiongkuo Lan, Long Zhai, Guangtao Ma, Kede The Institute of Image Communication and Information Processing Shanghai Jiao Tong University Shanghai200240 China The Department of Computer Science City University of Hong Kong Kowloon Hong Kong The Institute for Quantum Information State Key Laboratory of High Performance Computing College of Computer Science and Technology National University of Defense Technology Changsha410073 China The Institute of Image Communication and Information Processing The MoE Key Lab of Artificial Intelligence AI Institute Shanghai Jiao Tong University Shanghai200240 China The Department of Computer Science The Shenzhen Research Institute City University of Hong Kong Kowloon Hong Kong

Blind video quality assessment (BVQA) plays an indispensable role in monitoring and improving the end-users’ viewing experience in various real-world video-enabled media applications. As an experimental field, the improvements of BVQA models have been measured primarily on a few human-rated VQA datasets. Thus, it is crucial to gain a better understanding of existing VQA datasets in order to properly evaluate the current progress in BVQA. Towards this goal, we conduct a first-of-its-kind computational analysis of VQA datasets via designing minimalistic BVQA models. By minimalistic, we restrict our family of BVQA models to build only upon basic blocks: a video preprocessor (for aggressive spatiotemporal downsampling), a spatial quality analyzer, an optional temporal quality analyzer, and a quality regressor, all with the simplest possible instantiations. By comparing the quality prediction performance of different model variants on eight VQA datasets with realistic distortions, we find that nearly all datasets suffer from the easy dataset problem of varying severity, some of which even admit blind image quality assessment (BIQA) solutions. We additionally justify our claims by comparing our model generalization capabilities on these VQA datasets, and by ablating a dizzying set of BVQA design choices related to the basic building blocks. Our results cast doubt on the current progress in BVQA, and meanwhile shed light on good practices of constructing next-generation VQA datasets and models. Code is available at https://***/sunwei925/***. Copyright © 2023, The Authors. All rights reserved.

关键词： Deep neural networks

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Direct Observation of Magnon-Phonon Strong Coupling in Two-Dimensional Antiferromagnet at high Magnetic Fields

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Physical Review Letters 2021年第9期127卷 097401-097401页

作者： Sheng Liu Andrés Granados del Águila Dhiman Bhowmick Chee Kwan Gan T. Thu Ha Do M. A. Prosnikov David Sedmidubský Zdenek Sofer Peter C. M. Christianen Pinaki Sengupta Qihua Xiong Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University Singapore 637371 Institute of High Performance Computing 1 Fusionopolis Way 16-16 Connexis Singapore 138632 High Field Magnet Laboratory HFML-EMFL Radboud University 6525 ED Nijmegen Netherlands Department of Inorganic Chemistry University of Chemistry and Technology Prague Technická 5 166 28 Prague 6 Czech Republic State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics Tsinghua University Beijing 100084 China Beijing Academy of Quantum Information Sciences Beijing 100193 China

We report the direct observation of strong coupling between magnons and phonons in a two-dimensional antiferromagnetic semiconductor FePS3, via magneto-Raman spectroscopy at magnetic fields up to 30 Tesla. A Raman-active magnon at 121 cm−1 is identified through Zeeman splitting in an applied magnetic field. At a field-driven resonance with a nearby phonon mode, a hybridized magnon-phonon quasiparticle is formed due to strong coupling between the two modes. We develop a microscopic model of the strong coupling in the two-dimensional magnetic lattice, which enables us to elucidate the nature of the emergent quasiparticle. Our polarized Raman results directly show that the magnons transfer their spin angular momentum to the phonons and generate phonon spin through the strong coupling.

关键词： Magnons Raman spectroscopy

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STRATLEARN-Z: IMPROVED PHOTO-Z ESTIMATION FROM SPECTROSCOPIC DATA SUBJECT TO SELECTION EFFECTS

arXiv

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arXiv 2024年

作者： Moretti, Chiara Autenrieth, Maximilian Serra, Riccardo Trotta, Roberto van Dyk, David A. Mesinger, Andrei SISSA - International School for Advanced Studies Via Bonomea 265 Trieste34136 Italy Centro Nazionale "High Performance Computer Big Data and Quantum Computing" INAF – Osservatorio Astronomico di Trieste Via Tiepolo 11 TriesteI-34143 Italy INFN sezione di Trieste Italy Statistic Section Department of Mathematics Imperial College London 180 Queen’s Gate LondonSW7 2AZ United Kingdom Department of Physics Imperial College London Blackett Laboratory Prince Consort Rd LondonSW7 2AZ United Kingdom Piazza dei Cavalieri 7 PI Pisa56125 Italy

A precise measurement of photometric redshifts (photo-z) is crucial for the success of modern photometric galaxy surveys. Machine learning (ML) methods show great promise in this context, but suffer from covariate shift in training sets due to selection bias where interesting sources, e.g., high redshift objects, are underrepresented, and the corresponding ML models exhibit poor generalisation properties. We present an application of the StratLearn method to the estimation of photo-z (StratLearn-z), validating against simulations where we enforce the presence of covariate shift to different degrees. StratLearn is a statistically principled approach which relies on splitting the combined source and target datasets into strata, based on estimated propensity scores. The latter is the probability for an object in the dataset to be in the source set, given its observed covariates. After stratification, two conditional density estimators are fit separately within each stratum, and then combined via a weighted average. We benchmark our results against the GPz algorithm, quantifying the performance of the two algorithms with a set of metrics. Our results show that the StratLearn-z metrics are only marginally affected by the presence of covariate shift, while GPz shows a significant degradation of performance, specifically concerning the photo-z prediction for fainter objects for which there is little training data. In particular, for the strongest covariate shift scenario considered, StratLearn-z yields a reduced fraction of catastrophic errors, a factor of 2 improvement for the RMSE as well as one order of magnitude improvement on the bias. We also assess the quality of the predicted conditional redshift estimates using the probability integral transform (PIT). The PIT distribution obtained from StratLearn-z features far fewer outliers and is symmetric, i.e., the predictions appear to be well-centered around the true redshift value, despite showing a rather conservative es

关键词： Risk assessment

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Perovskite-type YRh3B with multiple types of nodal point and nodal line states

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Physical Review B 2021年第24期103卷 245126-245126页

作者： Feng Zhou Chaoxi Cui Jianhua Wang Minquan Kuang Tie Yang Zhi-Ming Yu Xiaotian Wang Gang Zhang Zhenxiang Cheng School of Physical Science and Technology Southwest University Chongqing 400715 China Key Lab of Advanced Optoelectronic Quantum Architecture and Measurement (MOE) Beijing Key Lab of Nanophotonics & Ultrafine Optoelectronic Systems and School of Physics Beijing Institute of Technology Beijing 100081 China Institute of High Performance Computing Agency for Science Technology and Research (A*STAR) 138632 Singapore Institute for Superconducting and Electronic Materials (ISEM) University of Wollongong Wollongong 2500 Australia

Experimentally synthesized perovskite-type YRh3B with a Pm3¯m type structure was proposed as a topological material (TM) via first-principles calculations and the low-energy k·p effective Hamiltonian, which has a quadratic contact triple point (QCTP) at point Γ and six pairs of open nodal lines (NLs) of the hybrid type. Clear surface states observed in the surface spectrum confirmed the topological states. When spin-orbit coupling was considered, the QCTP at Γ transferred to the quadratic-type Dirac nodal point (NP). Under 1% tetragonal strained lattice constants, YRh3B hosted richer topological states, including a quadratic-type twofold degenerate NP, six pairs of open NLs of the hybrid type, and two closed NLs of type I and hybrid type. Moreover, it was proved that the NLs of YRh3B at its strained lattice constants contain all types of band-crossing points (BCPs) (i.e., type I, type II, and critical type). Such rich types of NP and NL states in one compound make it potentially applicable for multifunctional electronic devices as well as an appropriate platform to study entanglement among topological states.

关键词： Density functional theory First-principles calculations Tight-binding model k dot p method

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CompressedMediQ: Hybrid quantum Machine Learning Pipeline for high-Dimensional Neuroimaging Data

CompressedMediQ: Hybrid Quantum Machine Learning Pipeline fo...

引用

Acoustics, Speech, and Signal Processing Workshops (ICASSPW), IEEE International Conference on

作者： Kuan-Cheng Chen Yi-Tien Li Tai-Yu Li Chen-Yu Liu Po-Heng Henry Lee Cheng-Yu Chen Department of Electrical and Electronic Engineering Imperial College London London UK Centre for Quantum Engineering Science and Technology (QuEST) Imperial College London London UK Translational Imaging Research Center Taipei Medical University Hospital Taipei Taiwan Research Center for Neuroscience Taipei Medical University Taipei Taiwan Ph.D. Program in Medical Neuroscience College of Medical Science and Technology Taipei Medical University Taipei Taiwan National Center for High-Performance Computing NARlabs Hsinchu Taiwan Graduate Institute of Applied Physics National Taiwan University Taipei Taiwan Department of Medical Imaging Taipei Medical University Hospital Taipei Taiwan Department of Radiology National Defense Medical Center Taipei Taiwan Department of Radiology School of Medicine College of Medicine Taipei Taiwan

ISBN: (数字)9798331519315

ISBN: (纸本)9798331519322

This paper introduces CompressedMediQ, a novel hybrid quantum-classical machine learning pipeline specifically developed to address the computational challenges associated with high-dimensional multi-class neuroimaging data analysis. Standard neuroimaging datasets, such as large-scale MRI data from the Alzheimer’s Disease Neuroimaging Initiative and Neuroimaging in Frontotemporal Dementia, present significant hurdles due to their vast size and complexity. CompressedMediQ integrates classical HPC nodes for advanced MRI pre-processing and Convolutional Neural Network (CNN)-PCA-based feature extraction and reduction, addressing the limited-qubit availability for quantum data encoding in the NISQ era. This is followed by quantum Support Vector Machine (QSVM) classification. By utilizing quantum kernel methods, the pipeline optimizes feature mapping and classification, enhancing data separability and outperforming traditional neuroimaging analysis techniques. Experimental results highlight the pipeline’s superior accuracy in dementia staging, validating the practical use of quantum machine learning in clinical diagnostics. Despite the limitations of NISQ devices, this proof-of-concept demonstrates the transformative potential of quantum-enhanced learning, paving the way for scalable and precise diagnostic tools in healthcare and signal processing.

关键词： Neuroimaging Support vector machines quantum computing Accuracy Magnetic resonance imaging Pipelines Machine learning Medical services Signal processing Standards

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