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We consider the reduced density matrix (RDM) \rho_A(t) for a finite subsystem A after a global quantum quench in the infinite transverse-field Ising chain. It has been recently shown that the infinite time limit of \rho_A(t) is described by…

Statistical Mechanics · Physics 2013-06-19 Maurizio Fagotti , Fabian H. L. Essler

The boundary stabilization problem of the Boussinesq KdV-KdV type system is investigated in this paper. An appropriate boundary feedback law consisting of a linear combination of a damping mechanism and a delay term is designed. Then,…

We consider finite-dimensional many-body quantum systems described by time-independent Hamiltonians and Markovian master equations, and present a systematic method for constructing smaller-dimensional, reduced models that exactly reproduce…

Quantum Physics · Physics 2025-07-30 Tommaso Grigoletto , Yukuan Tao , Francesco Ticozzi , Lorenza Viola

This paper studies the data-driven balanced truncation (BT) method for second-order systems based on the measurements in the frequency domain. The basic idea is to approximate Gramians used the numerical quadrature rules, and establish the…

Numerical Analysis · Mathematics 2025-06-05 Xiaolong Wang , Xuerong Yang , Xiaoli Wang , Bo Song

The nonequilibrium Green's functions (NEGF) approach is a versatile theoretical tool, which allows to describe the electronic structure, spectroscopy and dynamics of strongly correlated systems. The applicability of this method is, however,…

Strongly Correlated Electrons · Physics 2018-06-27 Michael Schüler , Martin Eckstein , Philipp Werner

We investigate the influence of a time dependent, homogeneous electric field on scattering properties of non-interacting electrons in an arbitrary static potential. We develop a method to calculate the (Keldysh) Green's function in two…

Disordered Systems and Neural Networks · Physics 2009-10-30 Tobias Brandes

Open quantum systems that feature non-Markovian dynamics are routinely solved using techniques such as the Hierarchical Equations of Motion (HEOM). However, their usage of the entire system density-matrix renders them intractable for…

Quantum Physics · Physics 2025-06-30 Kai Müller , Kimmo Luoma , Christian Schäfer

We investigate model order reduction (MOR) for linear dynamical systems, where a quadratic output is defined as a quantity of interest. The system can be transformed into a linear dynamical system with many linear outputs. MOR is feasible…

Numerical Analysis · Mathematics 2019-08-15 Roland Pulch , Akil Narayan

Localization methods reduce the path integrals in {\cal N} >= 2 supersymmetric Chern-Simons gauge theories on S^3 to multi-matrix integrals. A recent evaluation of such a two-matrix integral for the {\cal N}=6 superconformal U(N) x U(N)…

High Energy Physics - Theory · Physics 2015-03-17 Christopher P. Herzog , Igor R. Klebanov , Silviu S. Pufu , Tiberiu Tesileanu

We review different (reduced) models for thin structures using bending as principal mechanism to undergo large deformations. Each model consists in the minimization of a fourth order energy, potentially subject to a nonconvex constraint.…

Numerical Analysis · Mathematics 2023-05-25 Andrea Bonito , Diane Guignard , Angelique Morvant

The exponential computational cost of describing strongly correlated electrons can be mitigated by adopting a reduced density-matrix (RDM)-based description of the electronic structure. While variational two-electron RDM (v2RDM) methods can…

Chemical Physics · Physics 2026-01-06 Grier M. Jones , Run. R. Li , A. Eugene DePrince , Konstantinos D. Vogiatzis

The problem of mass diffusion in layered systems has relevance to applications in different scientific disciplines, e.g., chemistry, material science, soil science, and biomedical engineering. The mathematical challenge in these type of…

Statistical Mechanics · Physics 2020-10-28 Oded Farago

The Bogoliubov-Born-Green-Kirkwood-Yvon (BBGKY) hierarchy provides a time-reversal-symmetric framework for describing the nonequilibrium evolution of many-body systems. Despite the success of Boltzmann-based numerical approaches,…

Nuclear Theory · Physics 2026-03-25 Xingjian Lu , Shuzhe Shi

The Lipkin-Meshkov-Glick (LMG) model was devised to test the validity of different approximate formalisms to treat many-particle systems. The model was constructed to be exactly solvable and yet non-trivial, in order to capture some of the…

Nuclear Theory · Physics 2021-04-14 R. Romano , X. Roca-Maza , G. Colò , Shihang Shen

When solving partial differential equations numerically, usually a high order spatial discretisation is needed. Model order reduction (MOR) techniques are often used to reduce the order of spatially-discretised systems and hence reduce…

Optimization and Control · Mathematics 2017-09-19 Martin Redmann

A recently proposed linear-scaling scheme for density-functional pseudopotential calculations is described in detail. The method is based on a formulation of density functional theory in which the ground state energy is determined by…

mtrl-th · Physics 2009-10-28 E. Hernandez , C. M. Goringe , M. J. Gillan

The truncation scheme dependence of the exact renormalization group equations is investigated for scalar field theories in three dimensions. The exponents are numerically estimated to the next-to-leading order of the derivative expansion.…

High Energy Physics - Theory · Physics 2009-10-31 Ken-Ichi Aoki , Keiichi Morikawa , Wataru Souma , Jun-Ichi Sumi , Haruhiko Terao

We propose a new partially topological theory in three dimensions which couples Chern-Simons theory to matter. The 3-manifolds needed for this construction admit transverse holomorphic foliation (THF). The theory depends only on the choice…

High Energy Physics - Theory · Physics 2017-08-29 Mina Aganagic , Kevin Costello , Jacob McNamara , Cumrun Vafa

We analyzed the performance of a perturbation theory for nonlinear cosmological dynamics, based on the Lagrangian description of hydrodynamics. In our previous paper, we solved hydrodynamic equations for a self-gravitating fluid with…

Astrophysics · Physics 2009-11-10 Takayuki Tatekawa

Computing the stationary distributions of a continuous-time Markov chain (CTMC) involves solving a set of linear equations. In most cases of interest, the number of equations is infinite or too large, and the equations cannot be solved…

Probability · Mathematics 2020-08-25 Juan Kuntz , Philipp Thomas , Guy-Bart Stan , Mauricio Barahona