Quantum Signatures of Chaos from Free Probability

Fuente: arXiv
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Main Authors: Camargo, Hugo A., Fu, Yichao, Jahnke, Viktor, Pal, Kuntal, Kim, Keun-Young
Format: Preprint
Published: 2025
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author Camargo, Hugo A.
Fu, Yichao
Jahnke, Viktor
Pal, Kuntal
Kim, Keun-Young
author_facet Camargo, Hugo A.
Fu, Yichao
Jahnke, Viktor
Pal, Kuntal
Kim, Keun-Young
contents A classical dynamical system can be viewed as a probability space equipped with a measure-preserving time evolution map, admitting a purely algebraic formulation in terms of the algebra of bounded functions on the phase space. Similarly, a quantum dynamical system can be formulated using an algebra of bounded operators in a non-commutative probability space equipped with a time evolution map. Chaos, in either setting, can be characterized by statistical independence between observables at $ t = 0 $ and $ t \to \infty $, leading to the vanishing of cumulants involving these observables. In the quantum case, the notion of independence is replaced by free independence, which only emerges in the thermodynamic limit (asymptotic freeness). In this work, we propose a definition of quantum chaos based on asymptotic freeness and investigate its emergence in quantum many-body systems including the mixed-field Ising model with a random magnetic field, a higher spin version of the same model, and the SYK model. The hallmark of asymptotic freeness is the emergence of the free convolution prediction for the spectrum of operators of the form $ A(0) + B(t) $, implying the vanishing of all free cumulants between $A(0)$ and $B(t)$ in the thermodynamic limit for an infinite-temperature thermal state. We systematically investigate the spectral properties of $ A(0) + B(t) $ in the above-mentioned models, show that fluctuations on top of the free convolution prediction follow universal Wigner-Dyson statistics, and discuss the connection with quantum chaos. Finally, we argue that free probability theory provides a rigorous framework for understanding quantum chaos, offering a unifying perspective that connects many different manifestations of it.
format Preprint
id arxiv_https___arxiv_org_abs_2503_20338
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Quantum Signatures of Chaos from Free Probability
Camargo, Hugo A.
Fu, Yichao
Jahnke, Viktor
Pal, Kuntal
Kim, Keun-Young
High Energy Physics - Theory
Statistical Mechanics
Quantum Physics
A classical dynamical system can be viewed as a probability space equipped with a measure-preserving time evolution map, admitting a purely algebraic formulation in terms of the algebra of bounded functions on the phase space. Similarly, a quantum dynamical system can be formulated using an algebra of bounded operators in a non-commutative probability space equipped with a time evolution map. Chaos, in either setting, can be characterized by statistical independence between observables at $ t = 0 $ and $ t \to \infty $, leading to the vanishing of cumulants involving these observables. In the quantum case, the notion of independence is replaced by free independence, which only emerges in the thermodynamic limit (asymptotic freeness). In this work, we propose a definition of quantum chaos based on asymptotic freeness and investigate its emergence in quantum many-body systems including the mixed-field Ising model with a random magnetic field, a higher spin version of the same model, and the SYK model. The hallmark of asymptotic freeness is the emergence of the free convolution prediction for the spectrum of operators of the form $ A(0) + B(t) $, implying the vanishing of all free cumulants between $A(0)$ and $B(t)$ in the thermodynamic limit for an infinite-temperature thermal state. We systematically investigate the spectral properties of $ A(0) + B(t) $ in the above-mentioned models, show that fluctuations on top of the free convolution prediction follow universal Wigner-Dyson statistics, and discuss the connection with quantum chaos. Finally, we argue that free probability theory provides a rigorous framework for understanding quantum chaos, offering a unifying perspective that connects many different manifestations of it.
title Quantum Signatures of Chaos from Free Probability
topic High Energy Physics - Theory
Statistical Mechanics
Quantum Physics
url https://arxiv.org/abs/2503.20338