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We derive a stochastic hierarchy of matrix product states (HOMPS) for non-Markovian dynamics in open quantum system at finite temperature, which is numerically exact and efficient. HOMPS is obtained from the recently developed stochastic…

Quantum Physics · Physics 2022-04-04 Xing Gao , Jiajun Ren , Alexander Eisfeld , Zhigang Shuai

We construct upper bounds on entanglement entropies of many-body quantum states that have fixed energy expectation values with respect to geometrically local Hamiltonians. Our focus is on entanglement entropies of subsystems that make up…

Statistical Mechanics · Physics 2026-04-16 Samuel J. Garratt , Dmitry A. Abanin

We propose an efficient algorithm to numerically solve Anderson impurity problems using matrix product states. By introducing a modified chain mapping we obtain significantly lower entanglement, as compared to all previous attempts, while…

Strongly Correlated Electrons · Physics 2021-07-14 Lucas Kohn , Giuseppe E. Santoro

The study of generic properties of quantum states has led to an abundance of insightful results. A meaningful set of states that can be efficiently prepared in experiments are ground states of gapped local Hamiltonians, which are well…

Quantum Physics · Physics 2022-05-03 Jonas Haferkamp , Christian Bertoni , Ingo Roth , Jens Eisert

We define correlational (von Neumann) entropy for an individual quantum state of a system whose time-independent hamiltonian contains random parameters and is treated as a member of a statistical ensemble. This entropy is representation…

chao-dyn · Physics 2013-01-16 Valentin V. Sokolov , B. Alex Brown , Vladimir Zelevinsky

The local Hamiltonian problem consists of estimating the ground-state energy (given by the minimum eigenvalue) of a local quantum Hamiltonian. First, we show the existence of a good product-state approximation for the ground-state energy of…

Quantum Physics · Physics 2016-02-04 Fernando G. S. L. Brandão , Aram W. Harrow

An original method to exactly solve the non-Markovian Master Equation describing the interaction of a single harmonic oscillator with a quantum environment in the weak coupling limit is reported. By using a superoperatorial approach we…

Quantum Physics · Physics 2009-11-07 F. Intravaia , S. Maniscalco , A. Messina

One of the most important topics in the study of the dynamics of open quantum system is information exchange between system and environment. Based on the features of a back-flow information from an environment to a system, an approach is…

Quantum Physics · Physics 2015-09-23 S. Haseli , S. Salimi , A. S. Khorashad

The ground state energy and the free energy of Quantum Local Hamiltonians are fundamental quantities in quantum many-body physics, however, it is QMA-Hard to estimate them in general. In this paper, we develop new techniques to find…

Quantum Physics · Physics 2023-08-08 Thiago Bergamaschi

We describe a numerical algorithm for approximating the equilibrium-reduced density matrix and the effective (mean force) Hamiltonian for a set of system spins coupled strongly to a set of bath spins when the total system (system+bath) is…

Quantum Physics · Physics 2023-01-25 Tyler Chen , Yu-Chen Cheng

Characterizing nonequilibrium dynamics in quantum many-body systems is a challenging frontier of physics. In this Letter, we systematically construct solvable nonintegrable quantum circuits that exhibit exact hidden Markovian subsystem…

Quantum Physics · Physics 2024-11-22 He-Ran Wang , Xiao-Yang Yang , Zhong Wang

We use the eigenstate thermalization hypothesis to derive a quantum master equation for a system weakly coupled to a chaotic finite-sized bath prepared in a pure state. We show that the emergence of Markovianity is controlled by the…

Quantum Physics · Physics 2025-09-03 Peter O'Donovan , Philipp Strasberg , Kavan Modi , John Goold , Mark T. Mitchison

Stochastic thermodynamics allows us to define heat and work for microscopic systems far from thermodynamic equilibrium, based on observations of their stochastic dynamics. However, a complete account of the energetics necessitates that all…

Statistical Mechanics · Physics 2021-08-31 Jannik Ehrich

Entropy production plays a fundamental role in nonequilibrium thermodynamics to quantify the irreversibility of open systems. Its positivity can be ensured for a wide class of setups, but the entropy production rate can become negative…

Statistical Mechanics · Physics 2019-01-23 Philipp Strasberg , Massimiliano Esposito

We develop a numerical procedure to efficiently model the nonequilibrium steady state of one-dimensional arrays of open quantum systems, based on a matrix-product operator ansatz for the density matrix. The procedure searches for the null…

Quantum Physics · Physics 2015-08-26 Eduardo Mascarenhas , Hugo Flayac , Vincenzo Savona

We consider a computational problem where the goal is to approximate the maximum eigenvalue of a two-local Hamiltonian that describes Heisenberg interactions between qubits located at the vertices of a graph. Previous work has shed light on…

Quantum Physics · Physics 2020-06-11 Anurag Anshu , David Gosset , Karen Morenz

For one-dimensional spin and pseudospin models that allow mapping to a Markov chain, the free energy of the system at a finite temperature can be expressed in terms of bond concentrations. Minimizing the free energy function makes it…

Statistical Mechanics · Physics 2025-12-01 Yu. D. Panov

This study introduces a novel approach to derive a lower bound for the entropy production rate of a subsystem by utilizing the Cauchy-Schwarz inequality. It extends to establishing comprehensive upper and lower bounds for the efficiency of…

Statistical Mechanics · Physics 2024-07-04 Shihao Xia , Shuanglong Han , Ousi Pan , Yuzhuo Pan , Jincan Chen , Shanhe Su

The simulation of quantum systems is a task for which quantum computers are believed to give an exponential speedup as compared to classical ones. While ground states of one-dimensional systems can be efficiently approximated using Matrix…

Quantum Physics · Physics 2009-11-13 Norbert Schuch , Michael M. Wolf , Karl Gerd H. Vollbrecht , J. Ignacio Cirac

We consider overdamped physical systems evolving under a feedback-controlled fluctuating potential and in contact with a thermal bath at temperature $T$. A Markovian description of the dynamics, which keeps only the last value of the…

Statistical Mechanics · Physics 2026-02-12 Natalia Ruiz-Pino , Antonio Prados