Spread complexity in saddle-dominated scrambling

Fuente: arXiv
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Auteurs principaux: Huh, Kyoung-Bum, Jeong, Hyun-Sik, Pedraza, Juan F.
Format: Preprint
Publié: 2023
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author Huh, Kyoung-Bum
Jeong, Hyun-Sik
Pedraza, Juan F.
author_facet Huh, Kyoung-Bum
Jeong, Hyun-Sik
Pedraza, Juan F.
contents Recently, the concept of spread complexity, Krylov complexity for states, has been introduced as a measure of the complexity and chaoticity of quantum systems. In this paper, we study the spread complexity of the thermofield double state within \emph{integrable} systems that exhibit saddle-dominated scrambling. Specifically, we focus on the Lipkin-Meshkov-Glick model and the inverted harmonic oscillator as representative examples of quantum mechanical systems featuring saddle-dominated scrambling. Applying the Lanczos algorithm, our numerical investigation reveals that the spread complexity in these systems exhibits features reminiscent of \emph{chaotic} systems, displaying a distinctive ramp-peak-slope-plateau pattern. Our results indicate that, although spread complexity serves as a valuable probe, accurately diagnosing true quantum chaos generally necessitates additional physical input. We also explore the relationship between spread complexity, the spectral form factor, and the transition probability within the Krylov space. We provide analytical confirmation of our numerical results, validating the Ehrenfest theorem of complexity and identifying a distinct quadratic behavior in the early-time regime of spread complexity.
format Preprint
id arxiv_https___arxiv_org_abs_2312_12593
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Spread complexity in saddle-dominated scrambling
Huh, Kyoung-Bum
Jeong, Hyun-Sik
Pedraza, Juan F.
High Energy Physics - Theory
Chaotic Dynamics
Quantum Physics
Recently, the concept of spread complexity, Krylov complexity for states, has been introduced as a measure of the complexity and chaoticity of quantum systems. In this paper, we study the spread complexity of the thermofield double state within \emph{integrable} systems that exhibit saddle-dominated scrambling. Specifically, we focus on the Lipkin-Meshkov-Glick model and the inverted harmonic oscillator as representative examples of quantum mechanical systems featuring saddle-dominated scrambling. Applying the Lanczos algorithm, our numerical investigation reveals that the spread complexity in these systems exhibits features reminiscent of \emph{chaotic} systems, displaying a distinctive ramp-peak-slope-plateau pattern. Our results indicate that, although spread complexity serves as a valuable probe, accurately diagnosing true quantum chaos generally necessitates additional physical input. We also explore the relationship between spread complexity, the spectral form factor, and the transition probability within the Krylov space. We provide analytical confirmation of our numerical results, validating the Ehrenfest theorem of complexity and identifying a distinct quadratic behavior in the early-time regime of spread complexity.
title Spread complexity in saddle-dominated scrambling
topic High Energy Physics - Theory
Chaotic Dynamics
Quantum Physics
url https://arxiv.org/abs/2312.12593