Adiabatic gauge potential as a tool for detecting chaos in classical systems

The interplay between chaos and thermalization in weakly nonintegrable systems is a rich and complex subject. Interest in this area is further motivated by a desire to develop a unified picture of chaos for both quantum and classical systems. In this work, we study the adiabatic gauge potential (AGP...

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Main Authors: Nachiket Karve, Nathan Rose, David Campbell
Format: Article
Language:English
Published: American Physical Society 2025-07-01
Series:Physical Review Research
Online Access:http://doi.org/10.1103/1z5x-j644
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author Nachiket Karve
Nathan Rose
David Campbell
author_facet Nachiket Karve
Nathan Rose
David Campbell
author_sort Nachiket Karve
collection DOAJ
description The interplay between chaos and thermalization in weakly nonintegrable systems is a rich and complex subject. Interest in this area is further motivated by a desire to develop a unified picture of chaos for both quantum and classical systems. In this work, we study the adiabatic gauge potential (AGP), an object typically studied in quantum mechanics that describes deformations of a quantum state under adiabatic variation of the Hamiltonian, in classical Fermi-Pasta-Ulam-Tsingou (FPUT) and Toda models. We show how the time variance of the AGP over a trajectory probes the longtime correlations of a generic observable and can be used to distinguish among nearly integrable, weakly chaotic, and strongly chaotic regimes. We draw connections between the evolution of the AGP and diffusion and derive a fluctuation-dissipation relation that connects its variance to longtime correlations of the observable. Within this framework, we demonstrate that strongly and weakly chaotic regimes correspond to normal and anomalous diffusion, respectively. The latter gives rise to a marked increase in the variance as the time interval is increased, and this behavior serves as the basis for our probe of the onset times of chaos, which is interpreted as a “mixing” time. Numerical results are presented for FPUT and Toda systems that highlight integrable, weakly chaotic, and strongly chaotic regimes. Further, a hierarchy of t_{Lyapunov}<t_{chaos}<t_{thermalization} is found in these models. We conclude by commenting on the wide applicability of our method to a broader class of systems.
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spelling doaj-art-77ed374753dc49f7979206e73dff6d542025-08-20T03:15:47ZengAmerican Physical SocietyPhysical Review Research2643-15642025-07-017303300610.1103/1z5x-j644Adiabatic gauge potential as a tool for detecting chaos in classical systemsNachiket KarveNathan RoseDavid CampbellThe interplay between chaos and thermalization in weakly nonintegrable systems is a rich and complex subject. Interest in this area is further motivated by a desire to develop a unified picture of chaos for both quantum and classical systems. In this work, we study the adiabatic gauge potential (AGP), an object typically studied in quantum mechanics that describes deformations of a quantum state under adiabatic variation of the Hamiltonian, in classical Fermi-Pasta-Ulam-Tsingou (FPUT) and Toda models. We show how the time variance of the AGP over a trajectory probes the longtime correlations of a generic observable and can be used to distinguish among nearly integrable, weakly chaotic, and strongly chaotic regimes. We draw connections between the evolution of the AGP and diffusion and derive a fluctuation-dissipation relation that connects its variance to longtime correlations of the observable. Within this framework, we demonstrate that strongly and weakly chaotic regimes correspond to normal and anomalous diffusion, respectively. The latter gives rise to a marked increase in the variance as the time interval is increased, and this behavior serves as the basis for our probe of the onset times of chaos, which is interpreted as a “mixing” time. Numerical results are presented for FPUT and Toda systems that highlight integrable, weakly chaotic, and strongly chaotic regimes. Further, a hierarchy of t_{Lyapunov}<t_{chaos}<t_{thermalization} is found in these models. We conclude by commenting on the wide applicability of our method to a broader class of systems.http://doi.org/10.1103/1z5x-j644
spellingShingle Nachiket Karve
Nathan Rose
David Campbell
Adiabatic gauge potential as a tool for detecting chaos in classical systems
Physical Review Research
title Adiabatic gauge potential as a tool for detecting chaos in classical systems
title_full Adiabatic gauge potential as a tool for detecting chaos in classical systems
title_fullStr Adiabatic gauge potential as a tool for detecting chaos in classical systems
title_full_unstemmed Adiabatic gauge potential as a tool for detecting chaos in classical systems
title_short Adiabatic gauge potential as a tool for detecting chaos in classical systems
title_sort adiabatic gauge potential as a tool for detecting chaos in classical systems
url http://doi.org/10.1103/1z5x-j644
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AT nathanrose adiabaticgaugepotentialasatoolfordetectingchaosinclassicalsystems
AT davidcampbell adiabaticgaugepotentialasatoolfordetectingchaosinclassicalsystems