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We identify a large class of quantum many-body systems that can be solved exactly: natural frustration-free spin-1/2 nearest-neighbor Hamiltonians on arbitrary lattices. We show that the entire ground state manifold of such models can be…

Quantum Physics · Physics 2015-05-19 N. de Beaudrap , M. Ohliger , T. J. Osborne , J. Eisert

Generally, ``fracton'' topological orders are referred to as gapped phases that support \textit{point-like topological excitations} whose mobility is, to some extent, restricted. In our previous work [Phys. Rev. B 101, 245134 (2020)], a…

Strongly Correlated Electrons · Physics 2021-12-16 Meng-Yuan Li , Peng Ye

We present a general method to obtain the stable lasing solutions for the steady-state ab-initio lasing theory (SALT) for the case of a degenerate symmetric laser in two dimensions (2d). We find that under most regimes (with one…

We present exact ground states in spin models with orbital generacy in one and higher dimensions. A method to obtain the exact ground states of the models when the Hamiltonians are composed of the products of two commutable operators is…

Strongly Correlated Electrons · Physics 2009-10-31 Kazuhito Itoh

Due to an extremely rugged structure of the free energy landscape, the determination of spin-glass ground states is among the hardest known optimization problems, found to be NP-hard in the most general case. Owing to the specific structure…

Disordered Systems and Neural Networks · Physics 2011-11-10 Martin Weigel

A remarkable connection has been established for antiferromagnetic 2-spin systems, including the Ising and hard-core models, showing that the computational complexity of approximating the partition function for graphs with maximum degree D…

Computational Complexity · Computer Science 2014-11-05 Andreas Galanis , Daniel Stefankovic , Eric Vigoda

We present an exact algorithm for finding all the ground states of the two-dimensional Edwards-Anderson $\pm J$ spin glass and characterize its performance. We investigate how the ground states change with increasing system size and and…

Statistical Mechanics · Physics 2009-11-07 J. W. Landry , S. N. Coppersmith

While Nesterov's Accelerated Gradient Descent (AGD) efficiently solves constrained problems when the constraint set $X \subseteq \mathbb{R}^n$ is simple and easy to project onto, it remains an open question whether function-constrained…

Optimization and Control · Mathematics 2025-12-02 Zhe Zhang , Guanghui Lan

2D Gaussian Splatting (2DGS) has recently emerged as a promising method for novel view synthesis and surface reconstruction, offering better view-consistency and geometric accuracy than volumetric 3DGS. However, 2DGS suffers from severe…

Graphics · Computer Science 2025-11-04 Mae Younes , Adnane Boukhayma

Dipolar interactions are crucial in the modeling of many complex magnetic systems, such as the pyrochlores and artificial spin systems. Remarkably, many classical dipolar coupled spin systems exhibit a continuous ground-state degeneracy,…

Statistical Mechanics · Physics 2019-07-24 Dominik Schildknecht , Michael Schütt , Laura J. Heyderman , Peter M. Derlet

We apply optimization algorithms to the problem of finding ground states for crystalline surfaces and flux lines arrays in presence of disorder. The algorithms provide ground states in polynomial time, which provides for a more precise…

Condensed Matter · Physics 2009-10-28 Chen Zeng , A. Alan Middleton , Y. Shapir

In this paper we study the performance of the Projected Gradient Descent(PGD) algorithm for $\ell_{p}$-constrained least squares problems that arise in the framework of Compressed Sensing. Relying on the Restricted Isometry Property, we…

Numerical Analysis · Mathematics 2013-03-05 Sohail Bahmani , Bhiksha Raj

We consider the projected gradient algorithm for the nonconvex best subset selection problem that minimizes a given empirical loss function under an $\ell_0$-norm constraint. Through decomposing the feasible set of the given sparsity…

Optimization and Control · Mathematics 2026-02-13 Jan Harold Alcantara , Ching-pei Lee

Computing the ground state of Ising spin-glass models with p-spin interactions is, in general, an NP-hard problem. In this work we show that unlike in the case of the standard Ising spin glass with two-spin interactions, computing ground…

Disordered Systems and Neural Networks · Physics 2015-03-17 Creighton K. Thomas , Helmut G. Katzgraber

The projected entangled pair states (PEPS) methods have been proved to be powerful tools to solve the strongly correlated quantum many-body problems in two-dimension. However, due to the high computational scaling with the virtual bond…

Quantum Physics · Physics 2017-05-31 Wen-Yuan Liu , Shao-Jun Dong , Yong-Jian Han , Guang-Can Guo , Lixin He

Large numbers of ground states of two-dimensional Ising spin glasses with periodic boundary conditions in both directions are calculated for sizes up to 40^2. A combination of a genetic algorithm and Cluster-Exact Approximation is used. For…

Disordered Systems and Neural Networks · Physics 2009-10-31 Alexander K. Hartmann

Expander graphs play a central role in graph theory and algorithms. With a number of powerful algorithmic tools developed around them, such as the Cut-Matching game, expander pruning, expander decomposition, and algorithms for decremental…

Data Structures and Algorithms · Computer Science 2022-12-12 Julia Chuzhoy

We present a new proof for the 1D area law for frustration-free systems with a constant gap, which exponentially improves the entropy bound in Hastings' 1D area law, and which is tight to within a polynomial factor. For particles of…

Quantum Physics · Physics 2012-06-12 Itai Arad , Zeph Landau , Umesh Vazirani

Exact static nondegenerate stripe and checkerboard ground states are obtained in a two-dimensional generalized periodic Anderson model, for a broad concentration range below quarter filling. The random droplet states, also present in the…

Strongly Correlated Electrons · Physics 2025-03-25 Zsolt Gulacsi , Miklos Gulacsi

In this paper, we consider lasso problems with zero-sum constraint, commonly required for the analysis of compositional data in high-dimensional spaces. A novel algorithm is proposed to solve these problems, combining a tailored active-set…

Optimization and Control · Mathematics 2022-09-26 Andrea Cristofari