Average Equilibration Time for Gaussian Unitary Ensemble Hamiltonians

Fuente: arXiv
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Main Authors: Schwarzhans, Emanuel, Candeloro, Alessandro, Binder, Felix C., Lock, Maximilian P. E., Bakhshinezhad, Pharnam
Format: Preprint
Published: 2026
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_version_ 1866915899895709696
author Schwarzhans, Emanuel
Candeloro, Alessandro
Binder, Felix C.
Lock, Maximilian P. E.
Bakhshinezhad, Pharnam
author_facet Schwarzhans, Emanuel
Candeloro, Alessandro
Binder, Felix C.
Lock, Maximilian P. E.
Bakhshinezhad, Pharnam
contents Understanding equilibration times in closed quantum systems is essential for characterising their approach to equilibrium. Chaotic many-body systems are paradigmatic in this context: they are expected to thermalise according to the eigenstate thermalisation hypothesis and exhibit spectral properties well described by random matrix theory (RMT). While RMT successfully captures spectral correlations, its ability to provide quantitative predictions for equilibration timescales has remained largely unexplored. Here, we study equilibration within RMT using the framework of equilibration as dephasing, focusing on closed systems whose Hamiltonians are drawn from the Gaussian unitary ensemble (GUE). We derive an analytical expression that approximates the average equilibration time of the GUE and show that it is independent of both the initial state and the choice of observable, a consequence of the rotational invariance of the GUE. Numerical simulations confirm our analytical expression and demonstrate that our approximation is in close agreement with the true average equilibration time of the GUE. We find that the equilibration time decreases with system size and vanishes in the thermodynamic limit. This unphysical result indicates that the true equilibration timescale of realistic chaotic many-body systems must be dominated by physical features not captured by random matrix ensembles -- the GUE in particular.
format Preprint
id arxiv_https___arxiv_org_abs_2603_28587
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Average Equilibration Time for Gaussian Unitary Ensemble Hamiltonians
Schwarzhans, Emanuel
Candeloro, Alessandro
Binder, Felix C.
Lock, Maximilian P. E.
Bakhshinezhad, Pharnam
Quantum Physics
Understanding equilibration times in closed quantum systems is essential for characterising their approach to equilibrium. Chaotic many-body systems are paradigmatic in this context: they are expected to thermalise according to the eigenstate thermalisation hypothesis and exhibit spectral properties well described by random matrix theory (RMT). While RMT successfully captures spectral correlations, its ability to provide quantitative predictions for equilibration timescales has remained largely unexplored. Here, we study equilibration within RMT using the framework of equilibration as dephasing, focusing on closed systems whose Hamiltonians are drawn from the Gaussian unitary ensemble (GUE). We derive an analytical expression that approximates the average equilibration time of the GUE and show that it is independent of both the initial state and the choice of observable, a consequence of the rotational invariance of the GUE. Numerical simulations confirm our analytical expression and demonstrate that our approximation is in close agreement with the true average equilibration time of the GUE. We find that the equilibration time decreases with system size and vanishes in the thermodynamic limit. This unphysical result indicates that the true equilibration timescale of realistic chaotic many-body systems must be dominated by physical features not captured by random matrix ensembles -- the GUE in particular.
title Average Equilibration Time for Gaussian Unitary Ensemble Hamiltonians
topic Quantum Physics
url https://arxiv.org/abs/2603.28587