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Main Authors: Tan, Chengming, Wei, Zhiyang, Zhang, Ren
Format: Preprint
Published: 2024
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Online Access:https://arxiv.org/abs/2401.10499
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author Tan, Chengming
Wei, Zhiyang
Zhang, Ren
author_facet Tan, Chengming
Wei, Zhiyang
Zhang, Ren
contents In the study of quantum chaos diagnostics, considerable attention has been attributed to the Krylov complexity and spectrum form factor (SFF) for systems at infinite temperature. These investigations have unveiled universal properties of quantum chaotic systems. By extending the analysis to include the finite temperature effects on the Krylov complexity and SFF, we demonstrate that the Lanczos coefficients $b_n$, which are associated with the Wightman inner product, display consistency with the universal hypothesis presented in PRX 9, 041017 (2019). This result contrasts with the behavior of Lanczos coefficients associated with the standard inner product. Our results indicate that the slope $α$ of the $b_n$ is bounded by $πk_BT$, where $k_B$ is the Boltzmann constant and $T$ the temperature. We also investigate the SFF, which characterizes the two-point correlation of the spectrum and encapsulates an indicator of ergodicity denoted by $g$ in chaotic systems. Our analysis demonstrates that as the temperature decreases, the value of $g$ decreases as well. Considering that $α$ also represents the operator growth rate, we establish a quantitative relationship between ergodicity indicator and Lanczos coefficients slope. To support our findings, we provide evidence using the Gaussian orthogonal ensemble and a random spin model. Our work deepens the understanding of the finite temperature effects on Krylov complexity, SFF, and the connection between ergodicity and operator growth.
format Preprint
id arxiv_https___arxiv_org_abs_2401_10499
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publishDate 2024
record_format arxiv
spellingShingle Scaling Relations of Spectrum Form Factor and Krylov Complexity at Finite Temperature
Tan, Chengming
Wei, Zhiyang
Zhang, Ren
Statistical Mechanics
Disordered Systems and Neural Networks
Quantum Gases
Quantum Physics
In the study of quantum chaos diagnostics, considerable attention has been attributed to the Krylov complexity and spectrum form factor (SFF) for systems at infinite temperature. These investigations have unveiled universal properties of quantum chaotic systems. By extending the analysis to include the finite temperature effects on the Krylov complexity and SFF, we demonstrate that the Lanczos coefficients $b_n$, which are associated with the Wightman inner product, display consistency with the universal hypothesis presented in PRX 9, 041017 (2019). This result contrasts with the behavior of Lanczos coefficients associated with the standard inner product. Our results indicate that the slope $α$ of the $b_n$ is bounded by $πk_BT$, where $k_B$ is the Boltzmann constant and $T$ the temperature. We also investigate the SFF, which characterizes the two-point correlation of the spectrum and encapsulates an indicator of ergodicity denoted by $g$ in chaotic systems. Our analysis demonstrates that as the temperature decreases, the value of $g$ decreases as well. Considering that $α$ also represents the operator growth rate, we establish a quantitative relationship between ergodicity indicator and Lanczos coefficients slope. To support our findings, we provide evidence using the Gaussian orthogonal ensemble and a random spin model. Our work deepens the understanding of the finite temperature effects on Krylov complexity, SFF, and the connection between ergodicity and operator growth.
title Scaling Relations of Spectrum Form Factor and Krylov Complexity at Finite Temperature
topic Statistical Mechanics
Disordered Systems and Neural Networks
Quantum Gases
Quantum Physics
url https://arxiv.org/abs/2401.10499