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We study the nonequilibrium steady-state of a fully-coupled network of $N$ quantum harmonic oscillators, interacting with two thermal reservoirs. Given the long-range nature of the couplings, we consider two setups: one in which the number…

Statistical Mechanics · Physics 2022-09-27 Francesco Andreucci , Stefano Lepri , Stefano Ruffo , Andrea Trombettoni

Quantum systems of interest are typically coupled to several quantum channels (more generally environments). In this paper, we develop an exact stochastic Schr\"{o}dinger equation for an open quantum system coupled to a hybrid environment…

Quantum Physics · Physics 2017-05-11 Xinyu Zhao , Wufu Shi , J. Q. You , Ting Yu

Parity-time ($PT$)-symmetric Hamiltonians exhibit non-unitary dynamical evolution while maintaining real spectra, and offer unique approaches to quantum sensing and entanglement generation. Here we present a method for simulating the…

Quantum Physics · Physics 2026-01-15 Maryam Abbasi , Koray Aydogan , Anthony W. Schlimgen , Kade Head-Marsden

Tracing out the environmental degrees of freedom is a necessary procedure when simulating open quantum systems. While being an essential step in deriving a tractable master equation it represents a loss of information. In situations where…

Quantum Physics · Physics 2022-11-02 Dominic Gribben , Aidan Strathearn , Gerald E. Fux , Peter Kirton , Brendon W. Lovett

A canonical framework for chiral two--level systems coupled to a bath of harmonic oscillators is developed to extract, from a stochastic dynamics, the thermodynamic equilibrium values of both the population difference and coherences. The…

Statistical Mechanics · Physics 2013-08-26 H. C. Peñate-Rodriguez , A. Dorta-Urra , P. Bargueno , G. Rojas-Lorenzo , S. Miret-Artes

We introduce a hybrid classical-quantum algorithm to compute dynamical correlation functions and excitation spectra in many-body quantum systems, with a focus on molecular systems. The method combines classical preparation of a perturbed…

Quantum Physics · Physics 2025-10-30 Alessandro Santini , Stefano Barison , Filippo Vicentini

Obtaining the total wavefunction evolution of interacting quantum systems provides access to important properties, such as entanglement, shedding light on fundamental aspects, e.g. quantum energetics and thermodynamics, and guiding towards…

Quantum Physics · Physics 2022-02-02 Maria Maffei , Patrice A. Camati , Alexia Auffèves

We recently derived a spin-mapping approach for treating the nonadiabatic dynamics of a two-level system in a classical environment [J. Chem. Phys. 151, 044119 (2019)] based on the well-known quantum equivalence between a two-level system…

Chemical Physics · Physics 2020-03-03 Johan E. Runeson , Jeremy O. Richardson

Most non-relativistic interacting quantum many-body systems, such as atomic and molecular ensembles or materials, are naturally described in terms of continuous-space Hamiltonians. The simulation of their ground-state properties on digital…

Quantum Physics · Physics 2024-09-11 Friederike Metz , Gabriel Pescia , Giuseppe Carleo

Collision models provide a simple and versatile setting to capture the dynamics of open quantum systems. The standard approach to thermalisition in this setting involves an environment of independent and identically-prepared thermal qubits,…

Quantum Physics · Physics 2026-02-10 Ronan McElvogue , Andrew K. Mitchell , Gabriel T. Landi , Steve Campbell

We consider multiple non-interacting quantum mechanical two-level systems coupled to a common bosonic bath and study its quantum phase transition with Monte Carlo simulations using a continuous imaginary time cluster algorithm. The common…

Statistical Mechanics · Physics 2014-12-10 André Winter , Heiko Rieger

The dynamics of a wide range of technologically important quantum systems are dominated by their interaction with just a few environmental modes. Such highly structured environments give rise to long-lived bath correlations that induce…

Studies of the dynamics of a quantum system coupled to baths are typically performed by utilizing the Nakajima-Zwanzig memory kernel (${\mathcal{K}}$) or the influence functions ($\mathbf{{I}}$), especially when the dynamics exhibit memory…

Quantum Physics · Physics 2024-06-05 Felix Ivander , Lachlan P. Lindoy , Joonho Lee

We consider the physical model of a classical mechanical system (called "small system") undergoing repeated interactions with a chain of identical small pieces (called "environment"). This physical setup constitutes an advantageous way of…

Mathematical Physics · Physics 2011-11-04 Julien Deschamps

Classical simulation of quantum systems plays an important role in the study of many-body phenomena and in the benchmarking and verification of quantum technologies. Exact simulation is often limited to small systems because the dimension…

Quantum Physics · Physics 2024-06-04 Dominik S. Wild , Sabina Drăgoi , Corbin McElhanney , Jonathan Wurtz , Sheng-Tao Wang

The effective dynamics of a system interacting with a bath or environment is presented in two ways, (1) the (LGKS) replacement of the von Neuman equation for the density matrix and (2) the Feynman-Vernon path-integral derivation, by…

Quantum Physics · Physics 2023-12-29 Jose A. Magpantay

Path integral-based simulation methodologies play a crucial role for the investigation of nuclear quantum effects by means of computer simulations. However, these techniques are significantly more demanding than corresponding classical…

Statistical Mechanics · Physics 2018-01-17 Karsten Kreis , Kurt Kremer , Raffaello Potestio , Mark E. Tuckerman

Simulating the irreversible quantum dynamics of exciton and electron transfer problems poses a nontrivial challenge. Because the irreversibility of the system dynamics is a result of quantum thermal activation and dissipation caused by the…

Chemical Physics · Physics 2021-03-30 Seiji Ueno , Yoshitaka Tanimura

The dynamics of hybrid systems -- i.e. ones in which classical and quantum degrees of freedom co-exist and interact -- feature both diffusion in the classical sector and decoherence in the quantum state. In this article, we will consider…

Quantum Physics · Physics 2025-10-10 Emanuele Panella

We model a quantum system coupled to an environment of damped harmonic oscillators by following the approach of Caldeira-Leggett and adopting the Caldirola-Kanai Lagrangian for the bath oscillators. In deriving the master equation of the…

Quantum Physics · Physics 2023-03-17 Lester Buxton , Marc-Thomas Russo , Jim Al-Khalili , Andrea Rocco