Singular Value Decomposition and Its Blind Spot for Quantum Chaos in Non-Hermitian Sachdev-Ye-Kitaev Models

Fuente: arXiv
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Main Authors: Baggioli, Matteo, Huh, Kyoung-Bum, Jeong, Hyun-Sik, Jiang, Xuhao, Kim, Keun-Young, Pedraza, Juan F.
Format: Preprint
Published: 2025
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author Baggioli, Matteo
Huh, Kyoung-Bum
Jeong, Hyun-Sik
Jiang, Xuhao
Kim, Keun-Young
Pedraza, Juan F.
author_facet Baggioli, Matteo
Huh, Kyoung-Bum
Jeong, Hyun-Sik
Jiang, Xuhao
Kim, Keun-Young
Pedraza, Juan F.
contents The study of chaos and complexity in non-Hermitian quantum systems poses significant challenges due to the emergence of complex eigenvalues in their spectra. Recently, the singular value decomposition (SVD) method was proposed to address these challenges. In this work, we identify two critical shortcomings of the SVD approach when analyzing Krylov complexity and spectral statistics in non-Hermitian settings. First, we show that SVD fails to reproduce conventional eigenvalue statistics in the Hermitian limit for systems with non-positive definite spectra, as exemplified by a variant of the Sachdev-Ye-Kitaev (SYK) model. Second, and more fundamentally, Krylov complexity and spectral statistics derived via SVD cannot distinguish chaotic from integrable non-Hermitian dynamics, leading to results that conflict with complex spacing ratio analysis. Our findings reveal that SVD is inadequate for probing quantum chaos in non-Hermitian systems, and we advocate employing more robust methods, such as the bi-Lanczos algorithm, for future research in this direction.
format Preprint
id arxiv_https___arxiv_org_abs_2503_11274
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Singular Value Decomposition and Its Blind Spot for Quantum Chaos in Non-Hermitian Sachdev-Ye-Kitaev Models
Baggioli, Matteo
Huh, Kyoung-Bum
Jeong, Hyun-Sik
Jiang, Xuhao
Kim, Keun-Young
Pedraza, Juan F.
High Energy Physics - Theory
Statistical Mechanics
Chaotic Dynamics
Quantum Physics
The study of chaos and complexity in non-Hermitian quantum systems poses significant challenges due to the emergence of complex eigenvalues in their spectra. Recently, the singular value decomposition (SVD) method was proposed to address these challenges. In this work, we identify two critical shortcomings of the SVD approach when analyzing Krylov complexity and spectral statistics in non-Hermitian settings. First, we show that SVD fails to reproduce conventional eigenvalue statistics in the Hermitian limit for systems with non-positive definite spectra, as exemplified by a variant of the Sachdev-Ye-Kitaev (SYK) model. Second, and more fundamentally, Krylov complexity and spectral statistics derived via SVD cannot distinguish chaotic from integrable non-Hermitian dynamics, leading to results that conflict with complex spacing ratio analysis. Our findings reveal that SVD is inadequate for probing quantum chaos in non-Hermitian systems, and we advocate employing more robust methods, such as the bi-Lanczos algorithm, for future research in this direction.
title Singular Value Decomposition and Its Blind Spot for Quantum Chaos in Non-Hermitian Sachdev-Ye-Kitaev Models
topic High Energy Physics - Theory
Statistical Mechanics
Chaotic Dynamics
Quantum Physics
url https://arxiv.org/abs/2503.11274