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arXiv 2024年

作者： Zhao, Junjie Zhang, Chengxi Qin, Min Yang, Peng Guangdong Provincial Key Laboratory of Brain-Inspired Intelligent Computation Department of Computer Science and Engineering Southern University of Science and Technology Shenzhen518055 China Shenzhen Yujin Hedge Fund Company Limited Shenzhen518033 China Department of Modern Physics University of Science and Technology of China Hefei230026 China

The goal of alpha factor mining is to discover indicative signals of investment opportunities from the historical financial market data of assets, which can be used to predict asset returns and gain excess profits. Deep learning based alpha factor mining methods have shown to be powerful, which, however, lack of the interpretability, making them unacceptable in the risk-sensitive real markets. Alpha factors in formulaic forms are more interpretable and therefore favored by market participants, while the search space is complex and powerful explorative methods are urged. Recently, a promising framework is proposed for generating formulaic alpha factors using deep reinforcement learning, and quickly gained research focuses from both academia and industries. This paper first argues that the originally employed policy training method, i.e., Proximal Policy Optimization (PPO), faces several important issues in the context of alpha factors mining, making it ineffective to explore the search space of the formula. Herein, a novel reinforcement learning based on the well-known REINFORCE algorithm is proposed. Given that the underlying state transition function adheres to the Dirac distribution, the Markov Decision Process within this framework exhibit minimal environmental variability, making REINFORCE algorithm more appropriate than PPO. A new dedicated baseline is designed to theoretically reduce the commonly suffered high variance of REINFORCE. Moreover, the information ratio is introduced as a reward shaping mechanism to encourage the generation of steady alpha factors that can better adapt to changes in market volatility. Experimental evaluations on various real assets data show that the proposed algorithm can increase the correlation with asset returns by 3.83%, and a stronger ability to obtain excess returns compared to the latest alpha factors mining methods, which meets the theoretical results well. © 2024, CC BY.

关键词： Deep reinforcement learning

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In-Situ Single-Photon Detection of Er Sites in Si

In-Situ Single-Photon Detection of Er Sites in Si

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Conference on Lasers and Electro-Optics (CLEO)

作者： Ian R. Berkman Alexey Lyasota Gabriele G. de Boo John G. Bartholomew Brett C. Johnson Jeffrey C. McCallum Bin-Bin Xu Shouyi Xie Rose L. Ahlefeldt Matthew J. Sellars Chunming Yin Sven Rogge Centre of Excellence for Quantum Computation and Communication Technology School of Physics University of New South Wales Sydney New South Wales Australia Centre for Engineered Quantum Systems School of Physics The University of Sydney Sydney New South Wales Australia The University of Sydney Nano Institute The University of Sydney Sydney New South Wales Australia Centre of Excellence for Quantum Computation and Communication Technology School of Physics University of Melbourne Victoria Australia Centre of Excellence for Quantum Computation and Communication Technology School of Engineering RMIT University Victoria Australia Centre of Excellence for Quantum Computation and Communication Technology Research School of Physics Australian National University Canberra Australian Capital Territory Australia Hefei National Laboratory for Physical Sciences at the Microscale CAS Key Laboratory of Microscale Magnetic Resonance and School of Physical Sciences University of Science and Technology of China Hefei China

Using sample-on-SSPD and photoluminescence excitation spectroscopy, we demonstrate Er sites in Si with inhomogeneous broadening below 100 MHz, a 350 kHz upper bound on the homogeneous linewidth, and electron T 1 lowe... 详细信息

ISBN: (数字)9781957171050

ISBN: (纸本)9781665466660

关键词： Spectroscopy Upper bound Photoluminescence Lasers and electrooptics Nonhomogeneous media Silicon Laser excitation

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Berry Curvature and Bulk-Boundary Correspondence from Transport Measurement for Photonic Chern Bands

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Physical Review Letters 2023年第13期131卷 133601-133601页

作者： Chao Chen Run-Ze Liu Jizhou Wu Zu-En Su Xing Ding Jian Qin Lin Wang Wei-Wei Zhang Yu He Xi-Lin Wang Chao-Yang Lu Li Li Barry C. Sanders Xiong-Jun Liu Jian-Wei Pan Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics University of Science and Technology of China Hefei Anhui 230026 China CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics University of Science and Technology of China Shanghai 201315 China National Laboratory of Solid State Microstructures School of Physics Nanjing University Nanjing 210093 China Department of Physics Southern University of Science and Technology Shenzhen 518055 China The Physics Department and the Solid State Institute Technion–Israel Institute of Technology Haifa 3200003 Israel Department of Physics University of Konstanz D-78457 Konstanz Germany School of Computer Science Northwestern Polytechnical University Xi’an 710129 China Shenzhen Institute for Quantum Science and Engineering Southern University of Science and Technology Shenzhen 518055 China Institute for Quantum Science and Technology University of Calgary Alberta T2N 1N4 Canada International Center for Quantum Materials School of Physics Peking University Beijing 100871 China CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of Sciences Beijing 100190 China International Quantum Academy Shenzhen 518048 China

Berry curvature is a fundamental element to characterize topological quantum physics, while a full measurement of Berry curvature in momentum space was not reported for topological states. Here we achieve two-dimensional Berry curvature reconstruction in a photonic quantum anomalous Hall system via Hall transport measurement of a momentum-resolved wave packet. Integrating measured Berry curvature over the two-dimensional Brillouin zone, we obtain Chern numbers corresponding to −1 and 0. Further, we identify bulk-boundary correspondence by measuring topology-linked chiral edge states at the boundary. The full topological characterization of photonic Chern bands from Berry curvature, Chern number, and edge transport measurements enables our photonic system to serve as a versatile platform for further in-depth study of novel topological physics.

关键词： Quantum simulation Quantum walks Topological effects in photonic systems Topological phase transition Topological phases of matter

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Experimental demonstration of input-output indefiniteness in a single quantum device

arXiv

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arXiv 2022年

作者： Guo, Yu Liu, Zixuan Tang, Hao Hu, Xiao-Min Liu, Bi-Heng Huang, Yun-Feng Li, Chuan-Feng Guo, Guang-Can Chiribella, Giulio CAS Key Laboratory of Quantum Information University of Science and Technology of China Hefei230026 China CAS Center for Excellence in Quantum Information and Quantum Physics University of Science and Technology of China Hefei230026 China Hefei National Laboratory University of Science and Technology of China Hefei230088 China QICI Quantum Information and Computation Initiative Department of Computer Science The University of Hong Kong Pokfulam Road Hong Kong HKU-Oxford Joint Laboratory for Quantum Information and Computation Hong Kong Department of Computer Science University of Oxford Wolfson Building Parks Road Oxford United Kingdom Perimeter Institute for Theoretical Physics 31 Caroline Street North WaterlooON Canada

Quantum theory allows information to flow through a single device in a coherent superposition of two opposite directions, resulting into situations where the input-output direction is indefinite. Here we introduce a theoretical method to witness input-output indefiniteness in a single quantum device, and we experimentally demonstrate it by constructing a photonic setup that exhibits input-output indefiniteness with a statistical significance exceeding 69 standard deviations. Our results provide a way to characterize input-output indefiniteness as a resource for quantum information and photonic quantum technologies and enable table-top simulations of hypothetical scenarios exhibiting quantum indefiniteness in the direction of time. Copyright © 2022, The Authors. All rights reserved.

关键词： Quantum optics

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Logarithmic correction to black hole entropy from the nonlocality of quantum gravity

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Physical Review D 2022年第4期105卷 044013-044013页

作者： Yong Xiao Yu Tian Key Laboratory of High-precision Computation and Application of Quantum Field Theory of Hebei Province College of Physical Science and Technology Hebei University Baoding 071002 China School of Physics University of Chinese Academy of Sciences Beijing 100049 China Institute of Theoretical Physics Chinese Academy of Sciences Beijing 100190 China

It has been known for many years that the leading correction to the black hole entropy is a logarithmic term, which is universal and closely related to conformal anomaly. A fully consistent analysis of this issue has to take quantum backreactions to the black hole geometry into account. However, it was always unclear how to naturally derive the modified black hole metric, especially from an effective action, because the problem refers to the elusive nonlocality of quantum gravity. In this paper, we show that this problem can be resolved within an effective field theory (EFT) framework of quantum gravity. Our work suggests that the EFT approach provides a powerful and self-consistent tool for studying the quantum gravitational corrections to black hole geometries and thermodynamics.

关键词： Alternative gravity theories Quantum aspects of black holes Quantum gravity Effective field theory

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Single atom doping for quantum device development in diamond and silicon

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Journal of Vacuum science and technology B: Microelectronics and Nanometer Structures 2008年第6期26卷 2596-2600页

作者： Weis, C.D. Schuh, A. Batra, A. Persaud, A. Rangelow, I.W. Bokor, J. Lo, C.C. Cabrini, S. Sideras-Haddad, E. Fuchs, G.D. Hanson, R. Awschalom, D.D. Schenkel, T. Lawrence Berkeley National Laboratory 1 Cyclotron Road Berkeley CA 94114 United States Technical University Ilmenau D-98684 Ilmenau Germany Department of Electrical Engineering and Computer Science University of California Berkeley CA 94720 United States Molecular Foundry Lawrence Berkeley National Laboratory Berkeley CA 94720 United States School of Physics University of the Witwatersrand Wits 2050 Johannesburg South Africa Center for Spintronics and Quantum Computation University of California Santa Barbara CA 93106 United States Kavli Institute of Nanoscience Delft University of Technology P.O. Box 5046 2600 GA Delft Netherlands

The ability to inject dopant atoms with high spatial resolution, flexibility in dopant species, and high single ion detection fidelity opens opportunities for the study of dopant fluctuation effects and the development of devices in which function is based on the manipulation of quantum states in single atoms, such as proposed quantum computers. The authors describe a single atom injector, in which the imaging and alignment capabilities of a scanning force microscope (SFM) are integrated with ion beams from a series of ion sources and with sensitive detection of current transients induced by incident ions. Ion beams are collimated by a small hole in the SFM tip and current changes induced by single ion impacts in transistor channels enable reliable detection of single ion hits. They discuss resolution limiting factors in ion placement and processing and paths to single atom (and color center) array formation for systematic testing of quantum computer architectures in silicon and diamond. © 2008 American Vacuum Society.

关键词： Ion beams

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SpecDis: Value added distance catalogue for 4 million stars from DESI Year-1 data

arXiv

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arXiv 2025年

作者： Li, Songting Wang, Wenting Koposov, Sergey E. Li, Ting S. Wu, Youjia Valluri, Monica Najita, Joan Prieto, Carlos Allende Byström, Amanda Manser, Christopher J. Han, Jiaxin Palau, Carles G. Yang, Hao Cooper, Andrew P. Kizhuprakkat, Namitha Riley, Alexander H. Aguilar, Jessica Nicole Ahlen, Steven Bianchi, David Brooks, David Claybaugh, Todd de la Macorra, Axel Della Costa, John Dey, Arjun Doel, Peter Forero-Romero, Jaime E. Gaztañaga, Enrique Gontcho, Satya Gontcho A. Gutierrez, Gaston Honscheid, Klaus Ishak, Mustapha Juneau, Stephanie Kehoe, Robert Kisner, Theodore Landriau, Martin Guillou, Laurent Le Levi, Michael Manera, Marc Meisner, Aaron Miquel, Ramon Moustakas, John Palanque-Delabrouille, Nathalie Percival, Will Poppett, Claire Prada, Francisco Pérez-Ràfols, Ignasi Rossi, Graziano Sanchez, Eusebio Schlegel, David Schubnell, Michael Seo, Hee-Jong Silber, Joseph Harry Sprayberry, David Tarlé, Gregory Weaver, Benjamin Alan Zhou, Rongpu Zou, Hu Department of Astronomy Shanghai Jiao Tong University Shanghai200240 China Shanghai Key Laboratory for Particle Physics and Cosmology Shanghai200240 China State Key Laboratory of Dark Matter Physics School of Physics and Astronomy Shanghai Jiao Tong University Shanghai200240 China Institute for Astronomy University of Edinburgh Royal Observatory Blackford Hill EdinburghEH9 3HJ United Kingdom Institute of Astronomy University of Cambridge Madingley Road CambridgeCB3 0HA United Kingdom Department of Astronomy and Astrophysics University of Toronto 50 St. George Street TorontoONM5S 3H4 Canada Department of Physics University of Michigan 415 Church Street Ann ArborMI48105 United States Leinweber Center for Theoretical Physics University of Michigan 415 Church Street Ann ArborMI48105 United States NSF’s NOIRLab 950 N. Cherry Avenue TucsonAZ85719 United States Instituto de Astrofsica de Canarias C/ Va Lactea s/n Tenerife La LagunaE-38205 Spain Universidad de La Laguna Dpto. Astrofsica Tenerife La LagunaE-38206 Spain Imperial College London South Kensington Campus LondonSW7 2AZ United Kingdom Tsung-Dao Lee Institute Shanghai Jiao Tong University Shanghai201210 China Institute of Astronomy Department of Physics National Tsing Hua University 101 Kuang-Fu Rd. Sec. 2 Hsinchu30013 Taiwan Center for Informatics and Computation in Astronomy NTHU 101 Kuang-Fu Rd. Sec. 2 Hsinchu30013 Taiwan Institute for Computational Cosmology Department of Physics Durham University South Road DurhamDH1 3LE United Kingdom Lawrence Berkeley National Laboratory 1 Cyclotron Road BerkeleyCA94720 United States Physics Dept. Boston University 590 Commonwealth Avenue BostonMA02215 United States Dipartimento di Fisica "Aldo Pontremoli" Università degli Studi di Milano Via Celoria 16 MilanoI-20133 Italy INAF-Osservatorio Astronomico di Brera Via Brera 28 Milano20122 Italy Department of Physics & Astronomy University College London Gower Street London

We present the SpecDis value added stellar distance catalogue accompanying DESI DR1. SpecDis trains a feed-forward Neural Network (NN) on a large sample of stars with Gaia parallaxes, but without applying selections on parallax error or signal-to-noise (S/N) of the stellar spectra. We incorporate parallax error into the loss function for training. This approach ensures the training sample not suffering from biases. Moreover, SpecDis predicts the reciprocal of the square root of luminosity, which is linearly proportional to parallax and helps to avoid excluding negative parallaxes. To enhance the precision of distance predictions, we employ Principal Component Analysis (PCA) to reduce the noise and dimensionality of stellar spectra. Validated by independent external samples of member stars with precise distances from globular clusters, dwarf galaxies, and stellar streams, combined with BHB stars, we demonstrate that our distance measurements show no significant bias up to 100 kpc, and are much more precise than Gaia parallax beyond 7 kpc. The median distance uncertainties are 23%, 19%, 11% and 7% for S/Neff, indicating stars with low Fe and high α, which form early, may have experienced more encounters and tidal effects to disrupt binaries. Our final catalogue provides distances and distance uncertainties for >4 million stars, offering a valuable resource for Galactic astronomy. Copyright © 2025, The Authors. All rights reserved.

关键词： Galaxies

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A slug length calculation for a contraction with mean flow between two half cylinders 51

A slug length calculation for a contraction with mean flow b...

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51st International Congress and Exposition on Noise Control Engineering, Internoise 2022

作者： Na, Wei Yang, Dong Surendran, Aswathy Boij, Susann Morgans, Aimee Yao, Huadong Department of Mechanics and Maritime Sciences Chalmers University of Technology GothenburgSE-41296 Sweden Department of Mechanics and Aerospace Engineering Southern University of Science and Technology ShenZhenPR-518055 China Department of Engineering Physics and Computation Technical University of Munich MunichGE-85747 Germany KTH Royal Institute of Technology Marcus Wallenberg laboratory for Sound and Vibration Research Deptartment of Engineering Mechanics StockholmSE-10044 Sweden Department of Mechanical Engineering Imperial College London LondonSW72AZ United Kingdom

ISBN: (纸本)9781906913427

A slug length is widely used to describe additional mass inertia at low frequencies in duct acoustics. It is often used in acoustic energy analysis, e.g. as one of the inputs for semi-analytical or empirical models to obtain the acoustic reflection and transmission coefficients. However, the calculation of slug length is usually empirical and limited to certain conditions, such as simple geometric configurations, low frequencies, no mean flow, etc. In this paper, the slug length at a contraction with mean flow between two half cylinders is calculated by different methods: solving the Laplace's equation numerically, solving the Helmholtz equation, and using the Cummings - Fant equation based on the numerical results of frequency-domain linearized Navier-Stokes equations. Both the frequency-dependance and the mean flow effect are discussed. The calculated slug length can also be used as a crucial input, for example, in the Dowling and Hughes slit model and modified Cummings slit model to predict the acoustic scattering at tube rows in the presence of a cross mean flow[7]. © 2022 Internoise 2022 - 51st International Congress and Exposition on Noise Control Engineering. All rights reserved.

关键词： Cylinders (shapes)

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What is the Valence of Mn in Ga1−xMnxN?

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Physical Review Letters 2015年第19期115卷 197203-197203页

作者： Ryky Nelson Tom Berlijn Juana Moreno Mark Jarrell Wei Ku (顧威) Department of Physics and Astronomy Louisiana State University Baton Rouge Louisiana 70803 USA Center for Computation and Technology Louisiana State University Baton Rouge Louisiana 70803 USA Center for Nanophase Materials Sciences and Computer Science and Mathematics Division Oak Ridge National Laboratory Oak Ridge Tennessee 37831 USA Condensed Matter Physics and Materials Science Department Brookhaven National Laboratory Upton New York 11973 USA Physics Department State University of New York Stony Brook New York 11790 USA

We investigate the current debate on the Mn valence in Ga1−xMnxN, a diluted magnetic semiconductor (DMS) with a potentially high Curie temperature. From a first-principles Wannier-function analysis, we unambiguously find the Mn valence to be close to 2+ (d5), but in a mixed spin configuration with average magnetic moments of 4μB. By integrating out high-energy degrees of freedom differently, we further derive for the first time from first-principles two low-energy pictures that reflect the intrinsic dual nature of the doped holes in the DMS: (1) an effective d4 picture ideal for local physics, and (2) an effective d5 picture suitable for extended properties. In the latter, our results further reveal a few novel physical effects, and pave the way for future realistic studies of magnetism. Our study not only resolves one of the outstanding key controversies of the field, but also exemplifies the general need for multiple effective descriptions to account for the rich low-energy physics in many-body systems in general.

关键词： MANGANESE VALENCE (Chemistry) SEMICONDUCTORS MAGNETIC moments CURIE temperature

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Observation of thickness-tuned universality class in superconducting β-W thin films

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science Bulletin 2021年第18期66卷 1830-1838,M0003页

作者： Ce Huang Enze Zhang Yong Zhang Jinglei Zhang Faxian Xiu Haiwen Liu Xiaoyi Xie Linfeng Ai Yunkun Yang Minhao Zhao Junjie Qi Lun Li Shanshan Liu Zihan Li Runze Zhan Ya-Qing Bie Xufeng Kou Shaozhi Deng X.C.Xie State Key Laboratory of Surface Physics and Department of Physics Fudan UniversityShanghai 200433China Zhangjiang Fudan International Innovation Center Fudan UniversityShanghai 201210China School of Information Science and Technology ShanghaiTech UniversityShanghai 201210China Anhui Province Key Laboratory of Condensed Matter Physics at ExtremeConditions High Magnetic Field LaboratoryChinese Academy of SciencesHefei 230031China Collaborative Innovation Center of Advanced Microstructures Nanjing 210093China Shanghai Research Center for Quantum Sciences Shanghai 201315China Center for Advanced Quantum Studies Department of PhysicsBeijing Normal UniversityBeijing 100875China Beijing Academy of Quantum Information Sciences Beijing 100193China State Key Laboratory of Optoelectronic Materials and Technologies Guangdong Province Key Laboratory of Display Material and TechnologySchool of Electronics and Information TechnologySun Yat-sen UniversityGuangzhou 510275China International Center for Quantum Materials School of PhysicsPeking UniversityBeijing 100871China CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of SciencesBeijing 100190China

The interplay between quenched disorder and critical behavior in quantum phase transitions is conceptually fascinating and of fundamental importance for understanding phase transitions. However, it is still unclear whether or not the quenched disorder influences the universality class of quantum phase transitions. More crucially, the absence of superconducting-metal transitions under in-plane magnetic fields in 2D superconductors imposes constraints on the universality of quantum criticality. Here, we observe the thickness-tuned universality class of superconductor-metal transition by changing the disorder strength in b - W films with varying thickness. The finite-size scaling uncovers the switch of universality class: quantum Griffiths singularity to multiple quantum criticality at a critical thickness of tc⊥1~ 8 nm and then from multiple quantum criticality to single criticality at tc⊥2~ 16 nm. Moreover, the superconducting-metal transition is observed for the first time under in-plane magnetic fields and the universality class is changed at tc‖~ 8 nm. The observation of thickness-tuned universality class under both out-of-plane and in-plane magnetic fields provides broad information for the disorder effect on superconducting-metal transitions and quantum criticality.

关键词： Quenched disorder Quantum criticality Universality class quantum Griffiths singularity

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