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Leveraging matrix sparsity has proven a fruitful strategy for accelerating quantum chemical calculations. Here we present the hierarchical SOS-MP2 algorithm, which uses hierarchical matrix ($\mathcal{H}^{2}$) compression of the electron…

Chemical Physics · Physics 2025-06-23 Hongji Gao , Xiangmin Jiao , Benjamin G. Levine

We consider a lowest-order finite element discretization of the nonlinear system of Maxwell's and Landau-Lifshitz-Gilbert equations (MLLG). Two algorithms are proposed to numerically solve this problem, both of which only require the…

Numerical Analysis · Mathematics 2017-01-30 L'ubomir Banas , Marcus Page , Dirk Praetorius

During time evolution of many-body systems entanglement grows rapidly, limiting exact simulations to small-scale systems or small timescales. Quantum information tends however to flow towards larger scales without returning to local scales,…

Post-training quantization of Large Language Models (LLMs) is challenging. In this work, we introduce Low-rank Quantization Error Reduction (LQER), which combines quantization and low-rank approximation to recover the model capability. LQER…

Machine Learning · Computer Science 2024-05-31 Cheng Zhang , Jianyi Cheng , George A. Constantinides , Yiren Zhao

We propose a low-rank method for solving the Helmholtz equation. Our approach is based on the WaveHoltz method, which computes Helmholtz solutions by applying a time-domain filter to the solution of a related wave equation. The wave…

Numerical Analysis · Mathematics 2025-10-13 Andreas Granath , Daniel Appelö , Siyang Wang

We implement an efficient energy-minimization algorithm for finite-difference micromagnetics that proofs especially useful for the computation of hysteresis loops. Compared to results obtained by time integration of the…

Computational Physics · Physics 2014-10-27 Claas Abert , Gregor Wautischer , Florian Bruckner , Armin Satz , Dieter Suess

We introduce a quantum algorithm to perform the Laplace transform on quantum computers. Already, the quantum Fourier transform (QFT) is the cornerstone of many quantum algorithms, but the Laplace transform or its discrete version has not…

We demonstrate that the control protocols of quantum information devices can be simulated by assuming a low-rank ansatz for the density matrix. The rationale underlying this assumption is that quantum information protocols, by design,…

Quantum Physics · Physics 2026-01-27 Leo Goutte , Vincenzo Savona

The main purpose of this paper is the analytical study of self-shrinker solutions of the one-dimensional Landau-Lifshitz-Gilbert equation (LLG), a model describing the dynamics for the spin in ferromagnetic materials. We show that there is…

Analysis of PDEs · Mathematics 2020-05-22 Susana Gutiérrez , André de Laire

We consider the numerical approximation of a nonlinear system of partial differential equations modeling magnetostriction in the small-strain regime consisting of the Landau--Lifshitz--Gilbert equation for the magnetization and the…

Numerical Analysis · Mathematics 2026-04-01 Martin Kružík , Hywel Normington , Michele Ruggeri

Based on lowest-order finite elements in space, we consider the numerical integration of the Landau-Lifschitz-Gilbert equation (LLG). The dynamics of LLG is driven by the so-called effective field which usually consists of the exchange…

Numerical Analysis · Mathematics 2018-05-04 Dirk Praetorius , Michele Ruggeri , Bernhard Stiftner

Current quantization methods for LLMs predominantly rely on block-wise structures to maintain efficiency, often at the cost of representational flexibility. In this work, we demonstrate that element-wise quantization can be made as…

Machine Learning · Computer Science 2026-02-02 Pingzhi Tang , Ruijie Zhou , Fanxu Meng , Wenjie Pei , Muhan Zhang

We propose a method to improve the computational and memory efficiency of numerical solvers for the nonequilibrium Dyson equation in the Keldysh formalism. It is based on the empirical observation that the nonequilibrium Green's functions…

Strongly Correlated Electrons · Physics 2023-07-31 Jason Kaye , Denis Golež

Kohn-Sham spin-density functional theory provides an efficient and accurate model to study electron-electron interaction effects in quantum dots, but its application to large systems is a challenge. An efficient algorithm for the…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Hong Jiang , Harold U. Baranger , Weitao Yang

We resume the recent successes of the grid-based tensor numerical methods and discuss their prospects in real-space electronic structure calculations. These methods, based on the low-rank representation of the multidimensional functions and…

Numerical Analysis · Mathematics 2016-01-20 Venera Khoromskaia , Boris N. Khoromskij

Various applications ranging from spintronic devices, giant magnetoresistance sensors, and magnetic storage devices, include magnetic parts on very different length scales. Since the consideration of the Landau-Lifshitz-Gilbert equation…

In algorithms for solving optimization problems constrained to a smooth manifold, retractions are a well-established tool to ensure that the iterates stay on the manifold. More recently, it has been demonstrated that retractions are a…

Numerical Analysis · Mathematics 2024-03-11 Axel Séguin , Gianluca Ceruti , Daniel Kressner

The Landau-Lifshitz equation describes the dynamics of magnetization in ferromagnetic materials. Due to the essential nonlinearity and nonconvex constraint, it is typically solved numerically. In this paper, we developed a finite volume…

Numerical Analysis · Mathematics 2026-05-18 Yunjie Gong , Jingrun Chen , Rui Du , Panchi Li

Modeling quantum many-body systems is enormously challenging due to the exponential scaling of Hilbert dimension with system size. Finding efficient compressions of the wavefunction is key to building scalable models. Here, we introduce…

Computational Physics · Physics 2020-03-16 Christopher Roth

The autoencoder is an unsupervised learning paradigm that aims to create a compact latent representation of data by minimizing the reconstruction loss. However, it tends to overlook the fact that most data (images) are embedded in a…

Machine Learning · Computer Science 2023-10-26 Alokendu Mazumder , Tirthajit Baruah , Bhartendu Kumar , Rishab Sharma , Vishwajeet Pattanaik , Punit Rathore