Open quantum systems beyond equilibrium: Lindblad equation and path integral molecular dynamics

Fuente: arXiv
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Main Authors: Reible, Benedikt M., Ahmadkhani, Somayeh, Site, Luigi Delle
Format: Preprint
Published: 2026
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author Reible, Benedikt M.
Ahmadkhani, Somayeh
Site, Luigi Delle
author_facet Reible, Benedikt M.
Ahmadkhani, Somayeh
Site, Luigi Delle
contents The Lindblad equation determines the time evolution of the density operator of open quantum systems. While valid for any system size, its use is, in practice, restricted to prototype/surrogate models with the aim of tackling specific aspects of the overall quantum complexity of a multi-atomic system. Path integral molecular dynamics (PIMD) instead provides static and dynamical quantum statistical averages of physical observables for systems in equilibrium composed of up to thousands of atoms over timescales up to nanoseconds, under the condition that short-time quantum coherence is not relevant for the properties of interest. PIMD relies on the well-established technique of molecular dynamics (MD) with its associated classical trajectories. However, it cannot describe a direct time evolution of a system and its convergence to a stationary state in situations out of equilibrium. In this work, we analyze the link between the Lindblad equation and PIMD; specifically, we will discuss how PIMD can actually be used to calculate the time evolution of ensemble-averaged physical observables and their convergence to a stationary state for situations out of equilibrium, bypassing the need of explicitly solving the Lindblad equation. Yet, at the same time, the Lindblad equation and PIMD are linked to one another through a formal relation of equivalence, which provides an argument for the consistency of PIMD results, namely the positivity of the density operator at any time. A numerical study of a prototype system, which is of interest in chemical physics, will be used to showcase the method.
format Preprint
id arxiv_https___arxiv_org_abs_2603_10839
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Open quantum systems beyond equilibrium: Lindblad equation and path integral molecular dynamics
Reible, Benedikt M.
Ahmadkhani, Somayeh
Site, Luigi Delle
Quantum Physics
Statistical Mechanics
Computational Physics
The Lindblad equation determines the time evolution of the density operator of open quantum systems. While valid for any system size, its use is, in practice, restricted to prototype/surrogate models with the aim of tackling specific aspects of the overall quantum complexity of a multi-atomic system. Path integral molecular dynamics (PIMD) instead provides static and dynamical quantum statistical averages of physical observables for systems in equilibrium composed of up to thousands of atoms over timescales up to nanoseconds, under the condition that short-time quantum coherence is not relevant for the properties of interest. PIMD relies on the well-established technique of molecular dynamics (MD) with its associated classical trajectories. However, it cannot describe a direct time evolution of a system and its convergence to a stationary state in situations out of equilibrium. In this work, we analyze the link between the Lindblad equation and PIMD; specifically, we will discuss how PIMD can actually be used to calculate the time evolution of ensemble-averaged physical observables and their convergence to a stationary state for situations out of equilibrium, bypassing the need of explicitly solving the Lindblad equation. Yet, at the same time, the Lindblad equation and PIMD are linked to one another through a formal relation of equivalence, which provides an argument for the consistency of PIMD results, namely the positivity of the density operator at any time. A numerical study of a prototype system, which is of interest in chemical physics, will be used to showcase the method.
title Open quantum systems beyond equilibrium: Lindblad equation and path integral molecular dynamics
topic Quantum Physics
Statistical Mechanics
Computational Physics
url https://arxiv.org/abs/2603.10839