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We propose a boundary thermodynamic Bethe ansatz calculation technique to obtain the Loschmidt echo and the statistics of the work done when a global quantum quench is performed on an integrable quantum field theory. We derive an analytic…

Statistical Mechanics · Physics 2015-02-17 Tamas Palmai , Spyros Sotiriadis

The ground state energy and entropy of the dilute mean field Ising model is computed exactly by a single order parameter. An analogous exact solution is obtained in presence of a magnetic field with random locations. Results allow for a…

Disordered Systems and Neural Networks · Physics 2015-05-19 Maurizio Serva

We study the structure of the time evolution of the density matrix in contact with a thermal bath in a standard projection operator sheme. The reduced density matrix of the system in the steady state is obtained by tracing out the degree of…

Statistical Mechanics · Physics 2009-05-04 Takashi Mori , Seiji Miyashita

We study the local relaxation of closed quantum systems through the relative entropy between the reduced density matrix and its long time limit. We show, using analytic arguments combined with numerical checks, that this relative entropy…

Statistical Mechanics · Physics 2025-10-29 Filiberto Ares , Colin Rylands , Pasquale Calabrese

The asymmetric exclusion process on a ring in one-dimension is considered with a single defect particle. The steady state has previously been solved by a matrix product method. Here we use the Bethe ansatz to solve exactly for the long time…

Statistical Mechanics · Physics 2009-10-31 B. Derrida , M. R. Evans

Exact free energy minimization is a convex optimization problem that is usually approximated with stochastic sampling methods. Deterministic approximations have been less successful because many desirable properties have been difficult to…

Computational Physics · Physics 2016-03-17 Jonathan E. Moussa

We extend the ability of unitary quantum circuits by interfacing it with classical autoregressive neural networks. The combined model parametrizes a variational density matrix as a classical mixture of quantum pure states, where the…

Quantum Physics · Physics 2020-01-16 Jin-Guo Liu , Liang Mao , Pan Zhang , Lei Wang

We use statistical mechanics to study model-based Bayesian data clustering. In this approach, each partition of the data into clusters is regarded as a microscopic system state, the negative data log-likelihood gives the energy of each…

Disordered Systems and Neural Networks · Physics 2019-11-19 Alexander Mozeika , Anthony CC Coolen

We calculate various quantities that characterize the dissimilarity of reduced density matrices for a short interval of length $\ell$ in a two-dimensional (2D) large central charge conformal field theory (CFT). These quantities include the…

High Energy Physics - Theory · Physics 2017-12-25 Song He , Feng-Li Lin , Jia-ju Zhang

An expansion method for perturbation of the zero temperature grand canonical density matrix is introduced. The method achieves quadratically convergent recursions that yield the response of the zero temperature density matrix upon variation…

Materials Science · Physics 2009-11-10 Anders M. N. Niklasson , Matt Challacombe

This paper is our progress report on the project "Ising spectroscopy", devoted to systematic study of the mass spectrum of particles in 2D Ising Field Theory in a magnetic field. Here we address the low-temperature regime, and develop…

High Energy Physics - Theory · Physics 2007-05-23 Pedro Fonseca , Alexander Zamolodchikov

Although recent advances in simulating open quantum systems have lead to significant progress, the applicability of numerically exact methods is still restricted to rather small systems. Hence, more approximate methods remain relevant due…

Quantum Physics · Physics 2024-10-08 Yannick Marcel Holtkamp , Emiliano Godinez-Ramirez , Ulrich Kleinekathöfer

Motivated by the qualitative picture of Canonical Typicality, we propose a refined formulation of the Eigenstate Thermalization Hypothesis (ETH) for chaotic quantum systems. The new formulation, which we refer to as subsystem ETH, is in…

Statistical Mechanics · Physics 2018-04-06 Anatoly Dymarsky , Nima Lashkari , Hong Liu

If we prepare an isolated, interacting quantum system in an eigenstate and perturb a local observable at an initial time, its expectation value will relax towards a thermal expectation value, even though the time evolution of the system is…

Quantum Physics · Physics 2024-06-04 Tobias Helbig , Tobias Hofmann , Ronny Thomale , Martin Greiter

The approximate master equation (AME) provides a highly accurate description of dynamical processes on networks, yet its steady states are generally analytically intractable. In this study, we develop an analytical framework to derive the…

Physics and Society · Physics 2026-05-05 Yu Takiguchi , Takehisa Hasegawa

A random tiling of rectangles and triangles displaying a decagonal phase is solved by Bethe Ansatz. Analogously to the solutions of the dodecagonal square triangle and the octagonal rectangle triangle tiling an exact expression for the…

Statistical Mechanics · Physics 2009-10-30 Jan de Gier , Bernard Nienhuis

We consider a one-dimensional mixture of bosons and spinless fermions with contact interactions. In this system, the elementary excitations at low energies are described by four linearly dispersing modes characterized by two excitation…

Quantum Gases · Physics 2026-05-22 Soham Chandak , Aleksandra Petković , Zoran Ristivojevic

The performance of the quantum approximate optimization algorithm is evaluated by using three different measures: the probability of finding the ground state, the energy expectation value, and a ratio closely related to the approximation…

Quantum Physics · Physics 2020-06-08 Madita Willsch , Dennis Willsch , Fengping Jin , Hans De Raedt , Kristel Michielsen

Variational message passing (VMP), belief propagation (BP) and expectation propagation (EP) have found their wide applications in complex statistical signal processing problems. In addition to viewing them as a class of algorithms operating…

Information Theory · Computer Science 2021-01-20 Dan Zhang , Xiaohang Song , Wenjin Wang , Gerhard Fettweis , Xiqi Gao

The algebraic Bethe Ansatz is a prosperous and well-established method for solving one-dimensional quantum models exactly. The solution of the complex eigenvalue problem is thereby reduced to the solution of a set of algebraic equations.…

Strongly Correlated Electrons · Physics 2012-07-23 Valentin Murg , Vladimir E. Korepin , Frank Verstraete