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Few-photon single ionization of cold rubidium in the over-the-barrier regime

Physical Review A 2023年第3期107卷 033114-033114页

作者： Huanyu Ma Xincheng Wang Linxuan Zhang Zhihan Zou Junyang Yuan Yixuan Ma Rujin Lv Zhenjie Shen Tianmin Yan Matthias Weidemüller Difa Ye Yuhai Jiang Center for Transformative Science and School of Physical Science and Technology ShanghaiTech University Shanghai 201210 China Shanghai Advanced Research Institute Chinese Academy of Sciences Shanghai 201210 China School of Future Technology University of Chinese Academy of Sciences Beijing 100049 China Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Beijing 100088 China Graduate School China Academy of Engineering Physics Beijing 100193 China Physikalisches Institut Universität Heidelberg Im Neuenheimer Feld 226 69120 Heidelberg Germany

Photoionization of rubidium atoms cooled in a magneto-optical trap, characterized by the coexistence of the ground 5S1/2 and excited 5P3/2 states, is investigated experimentally and theoretically with the 400-nm femtosecond laser pulses at intensities of I=(3×109)–(4.5×1012) W/cm2. The recoil-ion momentum distribution (RIMD) of Rb+ exhibits rich ringlike structures and their energies correspond to one-photon ionization of the 5P3/2 state and two-photon and three-photon ionizations of the 5S1/2 state, respectively. With increasing I, the dips near zero momentum (NZM) in the experimental RIMDs become shallow dramatically and their peaked Rb+ momenta ionized from the 5P3/2 state move obviously toward zero while the peaks from the 5S1/2 state do not shift. In addition, the ion-yield ratio of the 5S1/2 state to the 5P3/2 state varies from I to I1.5 as I increases. These features indicate a transition from perturbative ionization to strongly perturbative ionization for the 5P3/2 state. Numerical simulations by solving the time-dependent Schrödinger equation (TDSE) can qualitatively explain the measurements of the RIMD, photoion angular distributions, and ion-yield ratio. However, some discrepancies still exist, especially for the NZM dip, which could stem from the electron-electron correlation that is neglected in the present TDSE simulations since we have adopted the single-active-electron approximation.

关键词： Atomic & molecular processes in external fields Multiphoton or tunneling ionization & excitation Single- and few-photon ionization & excitation

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DPA-2:a large atomic model as a multitask learner

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npj computational Materials 2024年第1期10卷 185-199页

作者： Duo Zhang Xinzijian Liu Xiangyu Zhang Chengqian Zhang Chun Cai Hangrui Bi Yiming Du Xuejian Qin Anyang Peng Jiameng Huang Bowen Li Yifan Shan Jinzhe Zeng Yuzhi Zhang Siyuan Liu Yifan Li Junhan Chang Xinyan Wang Shuo Zhou Jianchuan Liu Xiaoshan Luo Zhenyu Wang Wanrun Jiang Jing Wu Yudi Yang Jiyuan Yang Manyi Yang Fu-Qiang Gong Linshuang Zhang Mengchao Shi Fu-Zhi Dai Darrin M.York Shi Liu Tong Zhu Zhicheng Zhong Jian Lv Jun Cheng Weile Jia Mohan Chen Guolin Ke Weinan E Linfeng Zhang Han Wang AI for Science Institute BeijingP.R.China DP Technology BeijingP.R.China Academy for Advanced Interdisciplinary Studies Peking UniversityBeijingP.R.China State Key Lab of Processors Institute of Computing TechnologyChinese Academy of SciencesBeijingP.R.China University of Chinese Academy of Sciences BeijingP.R.China HEDPS CAPTCollege of EngineeringPeking UniversityBeijingP.R.China Ningbo Institute of Materials Technology and Engineering Chinese Academy of SciencesNingboP.R.China CAS Key Laboratory of Magnetic Materials and Devices and Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology Chinese Academy of SciencesNingboP.R.China School of Electronics Engineering and Computer Science Peking UniversityBeijingP.R.China Shanghai Engineering Research Center of Molecular Therapeutics&New Drug Development School of Chemistry and Molecular EngineeringEast China Normal UniversityShanghaiP.R.China Laboratory for Biomolecular Simulation Research Institute for Quantitative Biomedicine and Department of Chemistry and Chemical BiologyRutgers UniversityPiscatawayNJUSA Department of Chemistry Princeton UniversityPrincetonNJUSA College of Chemistry and Molecular Engineering Peking UniversityBeijingP.R.China Yuanpei College Peking UniversityBeijingP.R.China School of Electrical Engineering and Electronic Information Xihua UniversityChengduP.R.China State Key Laboratory of Superhard Materials College of PhysicsJilin UniversityChangchunP.R.China Key Laboratory of Material Simulation Methods&Software of Ministry of Education College of PhysicsJilin UniversityChangchunP.R.China International Center of Future Science Jilin UniversityChangchunP.R.China Key Laboratory for Quantum Materialsof Zhejiang Province Department of PhysicsSchool of ScienceWestlake UniversityHangzhouP.R.China Atomistic Simulations Italian Institute of TechnologyGenovaItaly State Key Laboratory of Physical Chemistry of Solid Surface iChEMCollege of Chemistry and Chemical EngineeringXiame

The rapid advancements in artificial intelligence(AI)are catalyzing transformative changes in atomic modeling,simulation,and ***-driven potential energy models havedemonstrated the capability to conduct large-scale,long-duration simulations with the accuracy of ab initio electronic structure ***,the model generation process remains a bottleneck for large-scale *** propose a shift towards a model-centric ecosystem,wherein a large atomic model(LAM),pretrained across multiple disciplines,can be efficiently fine-tuned and distilled for various downstream tasks,thereby establishing a new framework for molecular *** this study,we introduce the DPA-2 architecture as a prototype for ***-trained on a diverse array of chemical and materials systemsusing a multi-task approach,DPA-2demonstrates superior generalization capabilities across multiple downstream tasks compared to the traditional single-task pre-training and fine-tuning *** approach sets the stage for the development and broad application of LAMs in molecular and materials simulation research.

关键词： DPA establishing thereby

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Search for fractionally charged particles as lightly ionizing particles using public data from an underground direct detection experiment

arXiv

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arXiv 2025年

作者： Zhang Hu, J.W. Geng, X.P. Liu, F.L. Zhang, Z.H. Beijing Normal University at Zhuhai Zhuhai519087 China Beijing Honest Technology Co. Ltd. Beijing100083 China Institute of Applied Physics and Computational Mathematics Beijing100094 China China Institute of Atomic Energy Beijing102413 China Center for Nuclear Study The University of Tokyo Wako-shi351-0198 Japan China Nuclear Power Technology Research Institute Co. Ltd. Shenzhen518000 China

Approximately 60 years after the Milligan oil drop experiment in 1909, fractionally charged particles (FCPs) were reported to have been discovered in air-shower cores, and the search for FCPs continues to the present day in space, terrestrial and underground experiments. In this letter, relativistic FCPs are examined as lightly ionizing particles in underground direct detection on the basis of electron recoil data from XENON-nT. For FCPs from supernova shocks, the best results are obtained via direct detection, excluding the FCP charge of (3.6 × 10−9 − 1.0 × 10−2)·e corresponding to an FCP mass of 1 keV–556 GeV. For FCPs from general sources, the best limit is achieved, which is far ahead of other results in almost the entire parameter space, by excluding the FCP flux of (4.0 × 10−4 − 4.0 × 10−16) cm−2· s−1· sr−1 corresponding to the FCP charge of (1 × 10−6 − 1) · e. Copyright © 2025, The Authors. All rights reserved.

关键词： Supernovae

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Socio-Economic Assessment of the Impact of the Anticipated Sea Level Rise on Peloponnese Coast (Eastern Mediterranean)

SSRN

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SSRN 2023年

作者： Poulos, Serafeim E. Karditsa, Aikaterini Coastal & Marine Research Laboratory Institute of Applied and Computational Mathematics Foundation for Research and Technology-Hellas PO Box 1385 Crete Heraklion70013 Greece Laboratory of Physical Geography Section of Geography & Climatology Faculty of Geology & Geoenvironment National and Kapodistrian University of Athens Panepistimoupolis-Zografou TK Attiki15784 Greece Department of Port Management and Shipping National and Kapodistrian University of Athens Evripos Campus Greece

The 1455 km length of the coastline of the Peloponnese (southern Greece) is characterized by a variety of coastal landforms, mainly as a result of its geodynamic evolution and the prevailing coastal hydrodynamic conditions. In terms of coastal exposure to sea level rise highly vulnerable coasts include all types of depositional formations (beaches, deltas, lagoons), while low/very low vulnerability present rocky coasts with cliffs. The assessment of expected shoreline retreat due to sea level rise (SLR) by 2100 in 15 beach zones, representative of the 192 most touristic beaches in the Peloponnese, corresponds to approximately total loss of 37% (SSP1-2.6), 45% (SSP2-4.5) and 57% (SSP5-8.5). Adaptation to climate change impact could be achieved by applying Article 8 of Protocol 7 of the Barcelona Convention "Protocol on Integrated Coastal Zone Management in the Mediterranean", which asks for the identification of a zone at least 100 m wide from the higher limit of wave runup). In the case of Peloponnese this zone covers an area of 135 km2, consisting mostly of forests and grasslands (43.5%), cultivated land (30%), followed by wetlands (11.7%), artificial constructions (11.6%) and beaches/ dunes (3.1%);its integrated economic value in the range of 980 - 1240 Euro/m2. © 2023, The Authors. All rights reserved.

关键词： Beaches

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Robust ground-state energy estimation under depolarizing noise

arXiv

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arXiv 2023年

作者： Ding, Zhiyan Dong, Yulong Tong, Yu Lin, Lin Department of Mathematics University of California BerkeleyCA94720 United States Institute for Quantum Information and Matter California Institute of Technology PasadenaCA91125 United States Applied Mathematics and Computational Research Division Lawrence Berkeley National Laboratory BerkeleyCA94720 United States Challenge Institute of Quantum Computation University of California BerkeleyCA94720 United States

We present a novel ground-state energy estimation algorithm that is robust under global depolarizing error channels. Building upon the recently developed Quantum Exponential Least Squares (QCELS) algorithm, our new approach incorporates significant advancements to ensure robust estimation while maintaining a polynomial cost in precision. By leveraging the spectral gap of the Hamiltonian effectively, our algorithm overcomes limitations observed in previous methods like quantum phase estimation (QPE) and robust phase estimation (RPE). Going beyond global depolarizing error channels, our work underscores the significance and practical advantages of utilizing randomized compiling techniques to tailor quantum noise towards depolarizing error channels. Our research demonstrates the feasibility of ground-state energy estimation in the presence of depolarizing noise, offering potential advancements in error correction and algorithmic-level error mitigation for quantum algorithms. © 2023, CC BY.

关键词： Error correction

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Single-ancilla ground state preparation via Lindbladians

arXiv

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arXiv 2023年

作者： Ding, Zhiyan Chen, Chi-Fang Lin, Lin Department of Mathematics University of California BerkeleyCA94720 United States Institute for Quantum Information and Matter California Institute of Technology PasadenaCA91125 United States Applied Mathematics and Computational Research Division Lawrence Berkeley National Laboratory BerkeleyCA94720 United States Challenge Institute of Quantum Computation University of California BerkeleyCA94720 United States

We design a quantum algorithm for ground state preparation in the early fault tolerant regime. As a Monte Carlo-style quantum algorithm, our method features a Lindbladian where the target state is stationary. The construction of this Lindbladian is algorithmic and should not be seen as a specific approximation to some weakly coupled system-bath dynamics in nature. Our algorithm can be implemented using just one ancilla qubit and efficiently simulated on a quantum computer. It can prepare the ground state even when the initial state has zero overlap with the ground state, bypassing the most significant limitation of methods like quantum phase estimation. As a variant, we also propose a discrete-time algorithm, demonstrating even better efficiency and providing a near-optimal simulation cost depending on the desired evolution time and precision. Numerical simulation using Ising and Hubbard models demonstrates the efficacy and applicability of our method. © 2023, CC BY.

关键词： Quantum computers

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Dense outputs from quantum simulations

arXiv

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arXiv 2023年

作者： Liu, Jin-Peng Lin, Lin Department of Mathematics University of California Berkeley United States Simons Institute for the Theory of Computing University of California Berkeley United States Center for Theoretical Physics Massachusetts Institute of Technology Cambridge United States Applied Mathematics and Computational Research Division Lawrence Berkeley National Laboratory Berkeley United States Challenge Institute for Quantum Computation University of California Berkeley Berkeley United States

The quantum dense output problem is the process of evaluating time-accumulated observables from time-dependent quantum dynamics using quantum computers. This problem arises frequently in applications such as quantum control and spectroscopic computation. We present a range of algorithms designed to operate on both early and fully fault-tolerant quantum platforms. These methodologies draw upon techniques like amplitude estimation, Hamiltonian simulation, quantum linear Ordinary Differential Equation (ODE) solvers, and quantum Carleman linearization. We provide a comprehensive complexity analysis with respect to the evolution time T and error tolerance ǫ. Our results demonstrate that the linearization approach can nearly achieve optimal complexity O(T/ǫ) for a certain type of low-rank dense outputs. Moreover, we provide a linearization of the dense output problem that yields an exact and finite-dimensional closure which encompasses the original states. This formulation is related to the Koopman Invariant Subspace theory and may be of independent interest in nonlinear control and scientific machine learning. Copyright © 2023, The Authors. All rights reserved.

关键词： Linearization

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Suppressing electron disorder-induced heating of ultracold neutral plasma via optical lattice

arXiv

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arXiv 2023年

作者： Wang, HaiBo Yao, Zonglin Zhou, Fuyang Wu, Yong Wang, Jianguo Chen, Xiangjun Hefei National Research Center for Physical Sciences The Microscale Department of Modern Physics University of Science and Technology of China Anhui Hefei230026 China Hefei National Laboratory University of Science and Technology of China Anhui Hefei230088 China Institute of Applied Physics and Computational Mathematics Beijing100088 China

Disorder-induced heating (DIH) prevents ultracold neutral plasma into electron strong coupling regime. Here we propose a scheme to suppress electronic DIH via optical lattice. We simulate the evolution dynamics of ultracold neutral plasma constrained by three-dimensional optical lattice using classical molecular dynamics method. The results show that for experimentally achievable condition, electronic DIH is suppressed by a factor of 1.3, and the Coulomb coupling strength can reach to 0.8 which is approaching the strong coupling regime. Suppressing electronic DIH via optical lattice may pave a way for the research of electronic strongly coupled plasma. Copyright © 2023, The Authors. All rights reserved.

关键词： Optical lattices

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Dense Outputs from Quantum Simulations

SSRN

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SSRN 2023年

The quantum dense output problem is the process of evaluating time-accumulated observables from time-dependent quantum dynamics using quantum computers. This problem arises frequently in applications such as quantum control and spectroscopic computation. We present a range of algorithms designed to operate on both early and fully fault-tolerant quantum platforms. These methodologies draw upon techniques like amplitude estimation, Hamiltonian simulation, quantum linear Ordinary Differential Equation (ODE) solvers, and quantum Carleman linearization. We provide a comprehensive complexity analysis with respect to the evolution time $T$ and error tolerance $\epsilon$. Our results demonstrate that the linearization approach can nearly achieve optimal complexity $\mathcal{O}(T/\epsilon)$ for a certain type of low-rank dense outputs. Moreover, we provide a linearization of the dense output problem that yields an exact and finite-dimensional closure which encompasses the original states. This formulation is related to the Koopman Invariant Subspace theory and may be of independent interest in nonlinear control and scientific machine learning. © 2023, The Authors. All rights reserved.

关键词： Linearization

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Cauchy robust principal component analysis with applications to high-deimensional data sets

arXiv

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arXiv 2022年

作者： Fayomi, Ayisha Pantazis, Yannis Tsagris, Michail Wood, Andrew T.A. Department of Statistics King Abdulaziz University Jeddah Saudi Arabia Institute of Applied & Computational Mathematics Foundation for Research & Technology - Hellas Heraklion Greece Department of Economics University of Crete Gallos Campus Rethymnon Greece Research School of Finance Actuarial Studies & Statistics Australian National University Canberra Australia

Principal component analysis (PCA) is a standard dimensionality reduction technique used in various research and applied fields. From an algorithmic point of view, classical PCA can be formulated in terms of operations on a multivariate Gaussian likelihood. As a consequence of the implied Gaussian formulation, the principal components are not robust to outliers. In this paper, we propose a modified formulation, based on the use of a multivariate Cauchy likelihood instead of the Gaussian likelihood, which has the effect of robustifying the principal components. We present an algorithm to compute these robustified principal components. We additionally derive the relevant influence function of the first component and examine its theoretical properties. Simulation experiments on high-dimensional datasets demonstrate that the estimated principal components based on the Cauchy likelihood outperform or are on par with existing robust PCA techniques. © 2022, CC BY.

关键词： Principal component analysis

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