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Generating Approximate Ground States of Molecules Using Quantum Machine Learning

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arXiv 2022年

作者： Ceroni, Jack Stetina, Torin F. Kieferová, Mária Marrero, Carlos Ortiz Arrazola, Juan Miguel Wiebe, Nathan Xanadu TorontoONM5G 2C8 Canada Department of Mathematics University of Toronto TorontoONM5S 3E1 Canada Simons Institute for the Theory of Computing BerkeleyCA94704 United States Berkeley Quantum Information and Computation Center University of California BerkeleyCA94720 United States Centre for Quantum Computation and Communication Technology Centre for Quantum Software and Information University of Technology SydneyNSW2007 Australia AI & Data Analytics Division Pacific Northwest National Laboratory RichlandWA99354 United States Department of Electrical & Computer Engineering North Carolina State University RaleighNC27607 United States Department of Computer Science University of Toronto ONM5S 1A1 Canada High Performance Computing Group Pacific Northwest National Laboratory RichlandWA99354 United States

The potential energy surface (PES) of molecules with respect to their nuclear positions is a primary tool in understanding chemical reactions from first principles. However, obtaining this information is complicated by the fact that sampling a large number of ground states over a high-dimensional PES can require a vast number of state preparations. In this work, we propose using a generative quantum machine learning model to prepare quantum states at arbitrary points on the PES. The model is trained using quantum data consisting of ground-state wavefunctions associated with different classical nuclear coordinates. Our approach uses a classical neural network to convert the nuclear coordinates of a molecule into quantum parameters of a variational quantum circuit. The model is trained using a fidelity loss function to optimize the neural network parameters. We show that gradient evaluation is efficient and numerically demonstrate our method’s ability to prepare wavefunctions on the PES of hydrogen chains, water, and beryllium hydride. In all cases, we find that a small number of training points are needed to achieve very high overlap with the groundstates in practice. From a theoretical perspective, we further prove limitations on these protocols by showing that if we were able to learn across an avoided crossing using a small number of samples, then we would be able to violate Grover’s lower bound. Additionally, we prove lower bounds on the amount of quantum data needed to learn a locally optimal neural network function using arguments from quantum Fisher information. This work further identifies that quantum chemistry can be an important use case for quantum machine learning. © 2022, CC BY.

关键词： Molecules

Diabatic Quantum Annealing for the Frustrated Ring Model

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arXiv 2022年

作者： Côté, Jeremy Sauvage, Frédéric Larocca, Martín Jonsson, Matías Cincio, Lukasz Albash, Tameem Theoretical Division Los Alamos National Laboratory Los AlamosNM87545 United States Institut Quantique Département de Physique Université de Sherbrooke SherbrookeQCJ1K 2R1 Canada Center for Nonlinear Studies Los Alamos National Laboratory Los AlamosNM87545 United States Department of Physics Carnegie Mellon University PittsburghPA15217 United States Department of Electrical and Computer Engineering University of New Mexico AlbuquerqueNM87131 United States Department of Physics and Astronomy Center for Quantum Information and Control University of New Mexico AlbuquerqueNM87131 United States

Quantum annealing is a continuous-time heuristic quantum algorithm for solving or approximately solving classical optimization problems. The algorithm uses a schedule to interpolate between a driver Hamiltonian with an easy-to-prepare ground state and a problem Hamiltonian whose ground state encodes solutions to an optimization problem. The standard implementation relies on the evolution being adiabatic: keeping the system in the instantaneous ground state with high probability and requiring a time scale inversely related to the minimum energy gap between the instantaneous ground and excited states. However, adiabatic evolution can lead to evolution times that scale exponentially with the system size, even for computationally simple problems. Here, we study whether non-adiabatic evolutions with optimized annealing schedules can bypass this exponential slowdown for one such class of problems called the frustrated ring model. For sufficiently optimized annealing schedules and system sizes of up to 39 qubits, we provide numerical evidence that we can avoid the exponential slowdown. Our work highlights the potential of highly-controllable quantum annealing to circumvent bottlenecks associated with the standard implementation of quantum annealing. Copyright © 2022, The Authors. All rights reserved.

关键词： Ground state

Bio-inspired polarization event camera

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arXiv 2021年

作者： Haessig, Germain Joubert, Damien Haque, Justin Chen, Yingkai Milde, Moritz B. Delbruck, Tobi Gruev, Viktor AIT Austrian Institute of Technology Center for Vision Automation & Control High-performance Vision Systems Vienna Austria Institute of Neuroinformatics University of Zurich ETH Zurich Switzerland International Centre for Neuromorphic Systems The MARCS Institute Western Sydney University Sydney Australia Department of Electrical and Computer Engineering University of Illinois at Urbana-Champaign UrbanaIL United States

The stomatopod (mantis shrimp) visual system0 has recently provided a blueprint for the design of paradigm-shifting polarization and multispectral imaging sensors0, enabling solutions to challenging medical0 and remote sensing problems0. However, these bioinspired sensors lack the high dynamic range (HDR) and asynchronous polarization vision capabilities of the stomatopod visual system, limiting temporal resolution to ∼12 ms and dynamic range to ∼72 dB. Here we present a novel stomatopod-inspired polarization camera which mimics the sustained and transient biological visual pathways to save power and sample data beyond the maximum Nyquist frame rate. This bio-inspired sensor simultaneously captures both synchronous intensity frames and asynchronous polarization brightness change information with sub-millisecond latencies over a million-fold range of illumination. Our PDAVIS camera is comprised of 346x260 pixels, organized in 2-by-2 macropixels, which filter the incoming light with four linear polarization filters offset by 45°. Polarization information is reconstructed using both low cost and latency event-based algorithms and more accurate but slower deep neural networks. Our sensor is used to image HDR polarization scenes which vary at high speeds and to observe dynamical properties of single collagen fibers in bovine tendon under rapid cyclical loads. © 2021, CC BY.

关键词： Cameras

Glassy Behavior and Anomalous Transport in Chimney Ladder Crystals Induced by Soft Optical Phonons

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arXiv 2025年

作者： Mandyam, Srinivas V. Dong, Weicen Yan, Xiaoxian Zhao, Binru Lin, Junfa Xia, Tianlong Zhao, Zhiying Chen, Xi Ma, Jie Xing, Hui Grosche, F. Malte Baggioli, Matteo Department of Physics Harvard University CambridgeMA02135 United States Wilczek Quantum Center School of Physics and Astronomy Shanghai Jiao Tong University Shanghai200240 China Shanghai Research Center for Quantum Sciences Shanghai201315 China Key Laboratory of Artificial Structures and Quantum Control School of Physics and Astronomy Shanghai Jiao Tong University Shanghai200240 China Shanghai Center for Complex Physics School of Physics and Astronomy Shanghai Jiao Tong University Shanghai China School of Physics Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices Renmin University of China Beijing100872 China Renmin University of China Beijing100872 China Laboratory for Neutron Scattering Renmin University of China Beijing100872 China State Key Laboratory of Structural Chemistry Fujian Institute of Research The Structure of Matter Chinese Academy of Sciences Fujian Fuzhou350002 China Department of Electrical and Computer Engineering University of California RiversideCA92521 United States Collaborative Innovation Center of Advanced Microstructures Jiangsu Nanjing210093 China Cavendish Laboratory University of Cambridge JJ Thomson Avenue CambridgeCB30HE United Kingdom

Nowotny chimney ladder (NCL) crystals present physical properties in between the contrasting paradigms of ideal crystal and amorphous solid, making them promising candidates for thermoelectric applications due to their inherently low thermal conductivity. Here, we report an extensive experimental characterization of the thermodynamic and thermoelectric transport properties of a large class of NCL materials, focusing on the intermetallic compound Ru2Sn3−δ. We show that the heat capacity of these NCL compounds exhibits a boson-peak-like glassy anomaly between 8 K and 14 K. By combining experimental measurements with density functional theory (DFT), we attribute its microscopic origin to extremely soft optical phonons that universally appear as a consequence of the chimney ladder sublattice structure. Additionally, the measured thermal conductivity and the thermoelectric response present distinct anomalous glass-like features that strongly correlate with the dynamics of the abundant soft optical phonons revealed by DFT. Our work demonstrates that soft modes in ordered crystals can induce glassy behavior, outlining a pathway to design metallic materials with low thermal conductivity and unique thermoelectric properties without the need for disorder or strong electronic correlations. © 2025, CC BY.

关键词： Glass

Fundamental issues regarding uncertainties in artificial neural networks

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arXiv 2020年

作者： Thacker, N.A. Twining, C.J. Tar, P.D. Notley, S. Ramesh, V. Division of Informatics Imaging & Data Sciences University of Manchester United Kingdom Department of Computer Science University of Manchester United Kingdom Department of Automatic Control and Systems Engineering University of Sheffield United Kingdom Center for Cognition and Computation Goethe-Universität Frankfurt am Main Germany

Artificial Neural Networks (ANNs) implement a specific form of multi-variate extrapolation and will generate an output for any input pattern, even when there is no similar training pattern. Extrapolations are not necessarily to be trusted, and in order to support safety critical systems, we require such systems to give an indication of the training sample related uncertainty associated with their output. Some readers may think that this is a well known issue which is already covered by the basic principles of pattern recognition. We will explain below how this is not the case and how the conventional (Likelihood estimate of) conditional probability of classification does not correctly assess this uncertainty. We provide a discussion of the standard interpretations of this problem and show how a quantitative approach based upon long standing methods can be practically applied. The methods are illustrated on the task of early diagnosis of dementing diseases using Magnetic Resonance Imaging. Copyright © 2020, The Authors. All rights reserved.

关键词： Extrapolation

Master equations and quantum trajectories for squeezed wave packets

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arXiv 2021年

作者： Gross, Jonathan A. Baragiola, Ben Stace, T.M. Combes, Joshua Center for Quantum Information and Control University of New Mexico AlbuquerqueNM87131-0001 United States Institut Quantique Université de Sherbrooke SherbrookeQCJ1K 2R1 Canada Centre for Quantum Computation & Communication Technology School of Science RMIT University MelbourneVIC3000 Australia ARC Centre for Engineered Quantum System Department of Physics University of Queensland BrisbaneQLD4072 Australia Department of Electrical Computer and Energy Engineering University of Colorado Boulder BoulderCO80309 United States

The interaction between matter and squeezed light has mostly been treated within the approximation that the field correlation time is small. Methods for treating squeezed light with more general correlations currently involve explicitly modeling the systems producing the light. We develop a general purpose input-output theory for a particular form of narrowband squeezed light-a squeezed wave-packet mode-that only cares about the statistics of the squeezed field and the shape of the wave packet. This formalism allows us to derive the input-output relations and the master equation. We also consider detecting the scattered field using photon counting and homodyne measurements which necessitates the derivation of the stochastic master equation. The non Markovian nature of the field manifests itself in the master equation as a coupled hierarchy of equations. We illustrate these with consequences for the decay and resonance fluorescence of two-level atoms in the presence of such fields. Copyright © 2021, The Authors. All rights reserved.

关键词： Wave packets

How to Use the Internet Stock Message Board to Estimate the Dynamics of Stock Market 1

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2nd International Conference on Advanced Data and Information engineering, DaEng 2015

作者： Lee, Yun-Jung Cheon, Junseok Woo, Gyun Creative Human Resource Development Program for IT Convergence Pusan Nat’l University Busan609-735 Korea Republic of Department of Electrical and Computer Engineering Pusan Nat’l University Busan609-735 Korea Republic of Smart Control Center of LG Electronics Department of Electrical and Computer Engineering Pusan Nat’l University Busan609-735 Korea Republic of

ISBN: (数字)9789811317996

ISBN: (纸本)9789811317972

In this paper, we analyze the correlation between the stock prices and the human interactions in Internet stock message board. To uncover this correlation, we analyzed the articles concerning with 380 target companies, members of S&P500. And we found that the strength of correlation between the article volume and the stock prices is relevant to the stock returns. Based on this statistics analysis, we proposed a method for recommending stock portfolio and tested the method using a simulated investment. According to the test result, the stock returns of our portfolio is about 1.41% per a month, which is about 0.42% point and 0.15% point higher than those of the S&P500 index and of the Markowitz’s efficient portfolio respectively. This result implies that the collective human behavior on Internet stock message board can be much helpful to understand the stock market and that the correlation between the stock prices and the collective human behavior can be used to invest in stocks. © Springer Nature Singapore Pte Ltd. 2019.

关键词： Financial markets

Interplay between defects and the non-Hermitian skin effect

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arXiv 2025年

作者： Huang, Yin Zhang, Wenna Zhou, Yu Shen, Yuecheng Veronis, Georgios Luo, Wenchen School of Physics Central South University Changsha410083 China Department of Physics Jiangsu University of Science and Technology Jiangsu212003 China State Key Laboratory of Precision Spectroscopy East China Normal University Shanghai200241 China School of Electrical Engineering and Computer Science Louisiana State University Baton RougeLA70803 United States Center for Computation and Technology Louisiana State University Baton RougeLA70803 United States

The non-Hermitian skin effect (NHSE) is an intriguing phenomenon in which an extensive number of bulk eigenstates localize at the boundaries of a non-Hermitian system with non-reciprocal hoppings. Here we study the interplay of this effect and a defect in non-reciprocal one-dimensional lattices. We show that the interplay of the NHSE and defects is size-dependent. We demonstrate a novel class of hybrid skin-defect states in finite-size systems resulting from the coupling between the skin and defect states. Next, we consider a single defect in a topologically nontrivial lattice with time-reversal symmetry based on the non-reciprocal Su-Schrieffer-Heeger configuration. We unveil how topologically nontrivial defect states and non-Hermiticity interplay by competing with each other, exhibiting a transition from topologically nontrivial defect states to skin states. In addition, we show that decreasing the defect strength can result in a transition from trivial defect states to skin states. Our work promotes the understanding of the interplay between defects and the NHSE, and especially the importance of the energy spectra of the system with the defect under periodic boundary conditions. © 2025, CC BY.

关键词：

Customized quantum annealing schedules

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arXiv 2021年

作者： Khezri, Mostafa Dai, Xi Yang, Rui Albash, Tameem Lupascu, Adrian Lidar, Daniel A. Department of Electrical Engineering University of Southern California Los AngelesCA90089 United States Center for Quantum Information Science & Technology University of Southern California Los AngelesCA90089 United States Department of Physics and Astronomy University of Waterloo WaterlooON Canada Institute for Quantum Computing University of Waterloo WaterlooON Canada Department of Electrical and Computer Engineering University of New Mexico AlbuquerqueNM87131 United States Center for Quantum Information and Control CQuIC University of New Mexico AlbuquerqueNM87131 United States Department of Chemistry University of Southern California Los AngelesCA90089 United States Department of Physics University of Southern California Los AngelesCA90089 United States

In a typical quantum annealing protocol, the system starts with a transverse field Hamiltonian which is gradually turned off and replaced by a longitudinal Ising Hamiltonian. The ground state of the Ising Hamiltonian encodes the solution to the computational problem of interest, and the state overlap with this ground state gives the success probability of the annealing protocol. The form of the annealing schedule can have a significant impact on the ground state overlap at the end of the anneal, so precise control over these annealing schedules can be a powerful tool for increasing success probabilities of annealing protocols. Here we show how superconducting circuits, in particular capacitively shunted flux qubits (CSFQs), can be used to construct quantum annealing systems by providing tools for mapping circuit flux biases to Pauli coefficients. We use this mapping to find customized annealing schedules: appropriate circuit control biases that yield a desired annealing schedule, while accounting for the physical limitations of the circuitry. We then provide examples and proposals that utilize this capability to improve quantum annealing performance. Copyright © 2021, The Authors. All rights reserved.

关键词： Annealing