Observation of prethermalization in weakly nonintegrable unitary maps

Fuente: arXiv
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Main Authors: Zhang, Xiaodong, Lando, Gabriel M., Dietz, Barbara, Flach, Sergej
Format: Preprint
Published: 2025
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author Zhang, Xiaodong
Lando, Gabriel M.
Dietz, Barbara
Flach, Sergej
author_facet Zhang, Xiaodong
Lando, Gabriel M.
Dietz, Barbara
Flach, Sergej
contents We investigate prethermalization by studying the statistical properties of the time-dependent largest Lyapunov exponent $Λ(t)$ for unitary-circuit maps upon approaching integrability. We follow the evolution of trajectories for different initial conditions and compute the mean $μ(t)$ and standard deviation $σ(t)$ of $Λ(t)$. Thermalization implies a temporal decay $σ\sim t^{-1/2}$ at a converged finite value of $μ$. We report prethermalization plateaus that persist for long times where both $μ$ and $σ$ appear to have converged to finite values, seemingly implying differing saturated Lyapunov exponent values for different trajectories. The lifetime of such plateaus furnishes a novel time scale characterizing the thermalization dynamics of many-body systems close to integrability. We also find that the plateaus converge to their respective thermal values for long enough times.
format Preprint
id arxiv_https___arxiv_org_abs_2501_07956
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Observation of prethermalization in weakly nonintegrable unitary maps
Zhang, Xiaodong
Lando, Gabriel M.
Dietz, Barbara
Flach, Sergej
Chaotic Dynamics
Statistical Mechanics
We investigate prethermalization by studying the statistical properties of the time-dependent largest Lyapunov exponent $Λ(t)$ for unitary-circuit maps upon approaching integrability. We follow the evolution of trajectories for different initial conditions and compute the mean $μ(t)$ and standard deviation $σ(t)$ of $Λ(t)$. Thermalization implies a temporal decay $σ\sim t^{-1/2}$ at a converged finite value of $μ$. We report prethermalization plateaus that persist for long times where both $μ$ and $σ$ appear to have converged to finite values, seemingly implying differing saturated Lyapunov exponent values for different trajectories. The lifetime of such plateaus furnishes a novel time scale characterizing the thermalization dynamics of many-body systems close to integrability. We also find that the plateaus converge to their respective thermal values for long enough times.
title Observation of prethermalization in weakly nonintegrable unitary maps
topic Chaotic Dynamics
Statistical Mechanics
url https://arxiv.org/abs/2501.07956