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Anomaly detection under coordinate transformations

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Physical Review D 2023年第1期107卷 015009-015009页

作者： Gregor Kasieczka Radha Mastandrea Vinicius Mikuni Benjamin Nachman Mariel Pettee David Shih Institut für Experimentalphysik Universität Hamburg 22761 Hamburg Germany Department of Physics University of California Berkeley California 94720 USA Lawrence Berkeley National Laboratory Physics Division Berkeley California 94720 USA National Energy Research Scientific Computing Center Berkeley Laboratory Berkeley California 94720 USA Berkeley Institute for Data Science University of California Berkeley California 94720 USA New High Energy Theory Center Rutgers University Piscataway New Jersey 08854 USA

There is a growing need for machine-learning-based anomaly detection strategies to broaden the search for beyond-the-Standard-Model physics at the Large Hadron Collider (LHC) and elsewhere. The first step of any anomaly detection approach is to specify observables and then use them to decide on a set of anomalous events. One common choice is to select events that have low probability density. It is a well-known fact that probability densities are not invariant under coordinate transformations, so the sensitivity can depend on the initial choice of coordinates. The broader machine learning community has recently connected coordinate sensitivity with anomaly detection and our goal is to bring awareness of this issue to the growing high-energy physics literature on anomaly detection. In addition to analytical explanations, we provide numerical examples from simple random variables and from the LHC Olympics dataset that show how using probability density as an anomaly score can lead to events being classified as anomalous or not depending on the coordinate frame.

关键词： Particle production Hypothetical particles Hadron colliders Machine learning

Surrogate model for gravitational wave signals from nonspinning, comparable-to large-mass-ratio black hole binaries built on black hole perturbation theory waveforms calibrated to numerical relativity

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Physical Review D 2022年第10期106卷 104025-104025页

作者： Tousif Islam Scott E. Field Scott A. Hughes Gaurav Khanna Vijay Varma Matthew Giesler Mark A. Scheel Lawrence E. Kidder Harald P. Pfeiffer Department of Physics University of Massachusetts Dartmouth Massachusetts 02747 USA Department of Mathematics University of Massachusetts Dartmouth Massachusetts 02747 USA Center for Scientific Computing and Visualization Research University of Massachusetts Dartmouth Massachusetts 02747 USA Kavli Institute of Theoretical Physics University of California Santa Barbara Santa Barbara California 93106 USA Department of Physics and MIT Kavli Institute Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA Department of Physics University of Rhode Island Kingston Rhode Island 02881 USA Max Planck Institute for Gravitational Physics (Albert Einstein Institute) Am Mühlenberg 1 Potsdam 14476 Germany Cornell Center for Astrophysics and Planetary Science Cornell University Ithaca New York 14853 USA Theoretical Astrophysics Walter Burke Institute for Theoretical Physics California Institute of Technology Pasadena California 91125 USA

We present a reduced-order surrogate model of gravitational waveforms from nonspinning binary black hole systems with comparable to large mass-ratio configurations. This surrogate model, BHPTNRSur1dq1e4, is trained on waveform data generated by point-particle black hole perturbation theory (ppBHPT) with mass ratios varying from 2.5 to 10,000. BHPTNRSur1dq1e4 extends an earlier waveform model, EMRISur1dq1e4, by using an updated transition-to-plunge model, covering longer durations up to 30,500m1 (where m1 is the mass of the primary black hole), includes several more spherical harmonic modes up to ℓ=10, and calibrates subdominant modes to numerical relativity (NR) data. In the comparable mass-ratio regime, including mass ratios as low as 2.5, the gravitational waveforms generated through ppBHPT agree surprisingly well with those from NR after this simple calibration step. We also compare our model to recent SXS and RIT NR simulations at mass ratios ranging from 15 to 32, and find the dominant quadrupolar modes agree to better than ≈10−3. We expect our model to be useful to study intermediate-mass-ratio binary systems in current and future gravitational-wave detectors.

关键词： Gravitational waves

Minimum tracking linear response Hubbard and Hund corrected Density Functional Theory in CP2K

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arXiv 2024年

作者： Chai, Ziwei Si, Rutong Chen, Mingyang Teobaldi, Gilberto O'Regan, David D. Liu, Li-Min Beijing Computational Science Research Center Beijing100193 China School of Physics Beihang University Beijing100191 China School of Materials Science and Engineering University of Science and Technology Beijing Beijing100083 China Scientific Computing Department STFC UKRI Rutherford Appleton Laboratory Harwell Campus DidcotOX11 0QX United Kingdom School of Physics SFI AMBER Centre CRANN Institute Trinity College Dublin The University of Dublin Ireland

We present the implementation of the Hubbard (U) and Hund (J) corrected Density Functional Theory (DFT+U+J) functionality in the Quickstep program, which is part of the CP2K suite. The tensorial and Löwdin subspace representations are implemented and compared. Full analytical DFT+U+J forces are implemented and benchmarked for the tensorial and Löwdin representations. We also present the implementation of the recently proposed minimum-tracking linear-response method that enables the U and J parameters to be calculated on first principles basis without reference to the Kohn-Sham eigensystem. These implementations are benchmarked against recent results for different materials properties including DFT+U band gap opening in NiO, the relative stability of various polaron distributions in TiO2, the dependence of the calculated TiO2 band gap on +J corrections, and, finally, the role of the +U and +J corrections for the computed properties of a series of the hexahydrated transition metals. Our implementation provides results consistent with those already reported in the literature from comparable methods. We conclude the contribution with tests on the influence of the Löwdin orthonormalization on the occupancies, calculated parameters, and derived properties. © 2024, CC BY.

关键词： Titanium dioxide

The directional isotropy of LIGO-Virgo binaries

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arXiv 2023年

作者： Isi, Maximiliano Farr, Will M. Varma, Vijay Center for Computational Astrophysics Flatiron Institute 162 5th Ave New YorkNY10010 United States Department of Physics and Astronomy Stony Brook University Stony BrookNY11794 United States Am Mühlenberg 1 Potsdam14476 Germany Department of Mathematics Center for Scientific Computing and Data Science Research University of Massachusetts DartmouthMA02747 United States

We demonstrate how to constrain the degree of absolute alignment of the total angular momenta of LIGO-Virgo binary black holes, looking for a special direction in space that would break isotropy. We also allow for inhomogeneities in the distribution of black holes over the sky. Making use of dipolar models for the spatial distribution and orientation of the sources, we analyze 57 signals with false-alarm rates ≤ 1/yr from the third LIGO-Virgo observing run. Accounting for selection biases, we find the population of LIGO-Virgo black holes to be fully consistent with both homogeneity and isotropy. We additionally find the data to constrain some directions of alignment more than others, and produce posteriors for the directions of total angular momentum of all binaries in our set. All code and data are made publicly available in https://***/maxisi/gwisotropy/. © 2023, CC BY.

关键词： Black holes

Online-compatible unsupervised nonresonant anomaly detection

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Physical Review D 2022年第5期105卷 055006-055006页

作者： Vinicius Mikuni Benjamin Nachman David Shih National Energy Research Scientific Computing Center Berkeley Lab Berkeley California 94720 USA Physics Division Lawrence Berkeley National Laboratory Berkeley California 94720 USA Berkeley Institute for Data Science University of California Berkeley California 94720 USA NHETC Department of Physics & Astronomy Rutgers University Piscataway New Jersey 08854 USA

There is a growing need for anomaly detection methods that can broaden the search for new particles in a model-agnostic manner. Most proposals for new methods focus exclusively on signal sensitivity. However, it is not enough to select anomalous events—there must also be a strategy to provide context to the selected events. We propose the first complete strategy for unsupervised detection of nonresonant anomalies that includes both signal sensitivity and a data-driven method for background estimation. Our technique is built out of two simultaneously trained autoencoders that are forced to be decorrelated from each other. This method can be deployed off-line for nonresonant anomaly detection and is also the first complete on-line-compatible anomaly detection strategy. We show that our method achieves excellent performance on a variety of signals prepared for the ADC2021 data challenge.

关键词： Particle production Hypothetical particles Artificial neural networks Hadron colliders Machine learning

An asymptotically compatible coupling formulation for nonlocal interface problems with jumps

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arXiv 2022年

作者： Glusa, Christian D'Elia, Marta Capodaglio, Giacomo Gunzburger, Max Bochev, Pavel B. Center for Computing Research Sandia National Laboratories AlbuquerqueNM United States Data Science and Computing Group Sandia National Laboratories LivermoreCA United States Computational Physics and Methods Group Los Alamos National Laboratory Los AlamosNM United States Department of Scientific Computing Florida State University TallahasseeFL United States

We introduce a mathematically rigorous formulation for a nonlocal interface problem with jumps and propose an asymptotically compatible finite element discretization for the weak form of the interface problem. After proving the well-posedness of the weak form, we demonstrate that solutions to the nonlocal interface problem converge to the corresponding local counterpart when the nonlocal data are appropriately prescribed. Several numerical tests in one and two dimensions show the applicability of our technique, its numerical convergence to exact nonlocal solutions, its convergence to the local limit when the horizons vanish, and its robustness with respect to the patch test. Copyright © 2022, The Authors. All rights reserved.

关键词： Finite element method

Space-time collocation method: Loop quantum hamiltonian constraints

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arXiv 2020年

作者： Yonika, A. Heryudono, A. Khanna, G. Department of Physics Center for Scientific Computing and Visualization Research University of Massachusetts Dartmouth 285 Old Westport Road North DartmouthMA02747 United States Department of Mathematics Center for Scientific Computing and Visualization Research University of Massachusetts Dartmouth 285 Old Westport Road North DartmouthMA02747 United States

A space-time collocation method (STCM) using asymptotically-constant basis functions is proposed and applied to the quantum Hamiltonian constraint for a loop-quantized treatment of the Schwarzschild interior. Canonically, these descriptions take the form of a partial-difference equation (PDE). The space-time collocation approach presents a computationally efficient, convergent, and easily parallelizable method for solving this class of equations, which is the main novelty of this study. Results of the numerical simulations will demonstrate the benefit from a parallel computing approach;and show general exibility of the framework to handle arbitrarily-sized domains. Computed solutions will be compared, when applicable, to a solution computed in the conventional method via iteratively stepping through a predefined grid of discrete values, computing the solution via a recursive relationship. Copyright © 2020, The Authors. All rights reserved.

关键词： Gravitation

Hardware-Efficient Randomized Compiling

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arXiv 2024年

作者： Fruitwala, Neelay Hashim, Akel Rajagopala, Abhi D. Xu, Yilun Hines, Jordan Naik, Ravi K. Siddiqi, Irfan Klymko, Katherine Huang, Gang Nowrouzi, Kasra Accelerator Technology and Applied Physics Division Lawrence Berkeley National Lab BerkeleyCA94720 United States Department of Physics University of California at Berkeley BerkeleyCA94720 United States Applied Math and Computational Research Division Lawrence Berkeley National Lab BerkeleyCA94720 United States Materials Sciences Division Lawrence Berkeley National Lab BerkeleyCA94720 United States National Energy Research Scientific Computing Center Lawrence Berkeley National Lab BerkeleyCA94720 United States

Randomized compiling (RC) is an efficient method for tailoring arbitrary Markovian errors into stochastic Pauli channels. However, the standard procedure for implementing the protocol in software comes with a large experimental overhead — namely, it scales linearly in the number of desired randomizations, each of which must be generated and measured independently. In this work, we introduce a hardware-efficient algorithm for performing RC on a cycle-by-cycle basis on the lowest level of our FPGA-based control hardware during the execution of a circuit. Importantly, this algorithm performs a different randomization per shot with zero runtime overhead beyond measuring a circuit without RC. We implement our algorithm using the QubiC control hardware, where we demonstrate significant reduction in the overall runtime of circuits implemented with RC, as well as a significantly lower variance in measured observables. Copyright © 2024, The Authors. All rights reserved.

关键词： Field programmable gate arrays (FPGA)

Hardware-Assisted Parameterized Circuit Execution

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arXiv 2024年

作者： Rajagopala, Abhi D. Hashim, Akel Fruitwala, Neelay Huang, Gang Xu, Yilun Hines, Jordan Siddiqi, Irfan Klymko, Katherine Nowrouzi, Kasra Applied Math and Computational Research Division Lawrence Berkeley National Lab BerkeleyCA94720 United States Quantum Nanoelectronics Laboratory Department of Physics University of California at Berkeley BerkeleyCA94720 United States Accelerator Technology and Applied Physics Division Lawrence Berkeley National Lab BerkeleyCA94720 United States Department of Physics University of California at Berkeley BerkeleyCA94720 United States Materials Sciences Division Lawrence Berkeley National Lab BerkeleyCA94720 United States National Energy Research Scientific Computing Center Lawrence Berkeley National Lab BerkeleyCA94720 United States

Standard compilers for quantum circuits decompose arbitrary single-qubit gates into a sequence of physical Xπ/2 pulses and virtual-Z phase gates. Consequently, many circuit classes implement different logic operations but have an equivalent structure of physical pulses that only differ by changes in virtual phases. When many structurally-equivalent circuits need to be measured, generating sequences for each circuit is unnecessary and cumbersome, since compiling and loading sequences onto classical control hardware is a primary bottleneck in quantum circuit execution. In this work, we develop a hardware-assisted protocol for executing parameterized circuits on our FPGA-based control hardware, QubiC. This protocol relies on a hardware-software co-design technique in which software identifies structural equivalency in circuits and "peels" off the relevant parameterized angles to reduce the overall waveform compilation time. The hardware architecture then performs real-time "stitching" of the parameters in the circuit to measure circuits that implement a different overall logical operation. This work demonstrates significant speed ups in the total execution time for several different classes of quantum circuits. Copyright © 2024, The Authors. All rights reserved.

关键词： Quantum computers