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We describe a further development of the stochastic state selection method, a new Monte Carlo method we have proposed recently to make numerical calculations in large quantum spin systems. Making recursive use of the stochastic state…

Strongly Correlated Electrons · Physics 2009-11-11 Tomo Munehisa , Yasuko Munehisa

Lanczos-based methods have become standard tools for tasks involving matrix functions. Progress on these algorithms has been driven by several largely disjoint communities, resulting many innovative and important advancements which would…

Numerical Analysis · Mathematics 2024-10-16 Tyler Chen

We propose a new method to understand quantum entanglement using the thermo field dynamics (TFD) described by a double Hilbert space. The entanglement states show a quantum-mechanically complicated behavior. Our new method using TFD makes…

Statistical Mechanics · Physics 2013-05-22 Yoichiro Hashizume , Masuo Suzuki

This paper investigates numerical methods for approximating the ground state of Bose--Einstein condensates (BECs) by introducing two relaxed formulations of the Gross--Pitaevskii energy functional. These formulations achieve first- and…

Numerical Analysis · Mathematics 2025-07-30 Jing Guo , Yongyong Cai , Dong Wang

Land surface temperature (LST) is a critical parameter for characterizing surface energy balance and hydrothermal processes. While Landsat provides invaluable LST observations at medium spatial resolution for over 40 years, its native…

Atmospheric and Oceanic Physics · Physics 2026-04-01 Huanfeng Shen , Chan Li , Menghui Jiang , Penghai Wu , Guanhao Zhang , Tian Xie

The two-dimensional (2D) Hubbard model has long attracted interest for its rich phase diagram and its relevance to high-$T_c$ superconductivity. However, reliable finite-temperature studies remain challenging due to the exponential…

Strongly Correlated Electrons · Physics 2025-10-30 Changkai Zhang , Jan von Delft

In the case of a two-leg Hubbard ladder we present a procedure which allows the exact deduction of the ground state for the four particle problem in arbitrary large lattice system, in a tractable manner, which involves only a reduced…

Strongly Correlated Electrons · Physics 2009-11-11 Endre Kovacs , Zsolt Gulacsi

We present a finite-size scaling analysis of the droplet condensation-evaporation transition of a lattice gas (in two and three dimensions) and a Lennard-Jones gas (in three dimensions) at fixed density. Parallel multicanonical simulations…

Soft Condensed Matter · Physics 2015-08-04 Johannes Zierenberg , Wolfhard Janke

Within the framework of exact diagonalization (ED), we compute the ground state of Anderson impurity problem using the variational approach based on the configuration interaction (CI) expansion. We demonstrate that an accurate ground state…

Strongly Correlated Electrons · Physics 2013-07-19 Chungwei Lin , Alexander A. Demkov

We analyze the Lanczos method for matrix function approximation (Lanczos-FA), an iterative algorithm for computing $f(\mathbf{A}) \mathbf{b}$ when $\mathbf{A}$ is a Hermitian matrix and $\mathbf{b}$ is a given vector. Assuming that $f :…

Numerical Analysis · Mathematics 2022-05-19 Tyler Chen , Anne Greenbaum , Cameron Musco , Christopher Musco

We propose a two-sided Lanczos method for the nonlinear eigenvalue problem (NEP). This two-sided approach provides approximations to both the right and left eigenvectors of the eigenvalues of interest. The method implicitly works with…

Numerical Analysis · Mathematics 2016-07-13 Sarah W. Gaaf , Elias Jarlebring

We present an algorithm that uses block encoding on a quantum computer to exactly construct a Krylov space, which can be used as the basis for the Lanczos method to estimate extremal eigenvalues of Hamiltonians. While the classical Lanczos…

Quantum Physics · Physics 2023-05-24 William Kirby , Mario Motta , Antonio Mezzacapo

We study mixed state entanglement measures in a higher dimensional $T\bar{T}$ deformed field theory at finite temperature. The holographic dual is described by AdS$_{d+1}$ black brane geometry with a finite cutoff. We compute the…

High Energy Physics - Theory · Physics 2025-04-28 Sanjay Pant , Himanshu Parihar

An exact analytical diagonalization is used to solve the two dimensional Extended Hubbard Model for system with finite size. We have considered an Extended Hubbard Model (EHM) including on-site and off-site interactions with interaction…

Statistical Mechanics · Physics 2015-06-03 S. Harir , M. Bennai , Y. Boughaleb

A new iterative method for solving large scale symmetric nonlinear eigenvalue problems is presented. We firstly derive an infinite dimensional symmetric linearization of the nonlinear eigenvalue problem, then we apply the indefinite Lanczos…

Numerical Analysis · Mathematics 2019-10-11 Giampaolo Mele

In this paper, we propose a regularized Newton method for computing ground states of Bose-Einstein condensates (BECs), which can be formulated as an energy minimization problem with a spherical constraint. The energy functional and…

Numerical Analysis · Mathematics 2017-11-21 Xinming Wu , Zaiwen Wen , Weizhu Bao

We investigate the creation of highly entangled ground states in a system of three exchange-coupled qubits arranged in a ring geometry. Suitable magnetic field configurations yielding approximate GHZ and exact W ground states are…

Quantum Physics · Physics 2008-03-19 Beat Röthlisberger , Jörg Lehmann , D. S. Saraga , Philipp Traber , Daniel Loss

Excited-state effects lead to hard-to-quantify systematic uncertainties in lattice quantum chromodynamics (LQCD) spectroscopy calculations when computationally accessible imaginary times are smaller than inverse excitation gaps, as often…

High Energy Physics - Lattice · Physics 2026-02-02 William Detmold , Anthony V. Grebe , Daniel C. Hackett , Marc Illa , Robert J. Perry , Phiala E. Shanahan , Michael L. Wagman

We report an implementation of the recursion method that addresses quantum many-body dynamics in the nonperturbative regime. The method essentially amounts to constructing a Lanczos basis in the space of operators and solving coupled…

Strongly Correlated Electrons · Physics 2024-04-11 Filipp Uskov , Oleg Lychkovskiy

Tensor network methods as presented in our open source Matrix Product States software have opened up the possibility to study many-body quantum physics in one and quasi-one-dimensional systems in an easily accessible package similar to…

Quantum Gases · Physics 2018-10-29 Daniel Jaschke , Lincoln D. Carr