Quantum complexity and localization in random and time-periodic unitary circuits

Fuente: arXiv
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Autores principales: Sahu, Himanshu, Bhattacharya, Aranya, Nath, Pingal Pratyush
Formato: Preprint
Publicado: 2024
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author Sahu, Himanshu
Bhattacharya, Aranya
Nath, Pingal Pratyush
author_facet Sahu, Himanshu
Bhattacharya, Aranya
Nath, Pingal Pratyush
contents We study the growth and saturation of Krylov spread (K-) complexity under random quantum circuits. In Haar-random unitary evolution, we show that, for large system sizes, K-complexity grows linearly before saturating at a late-time value of $D/2$, where $D$ is the Hilbert space dimension, at timescales $\sim D$. Our numerical analysis encompasses two classes of random circuits: brick-wall random unitary circuits and Floquet random circuits. In brick-wall case, K-complexity exhibits dynamics consistent with Haar-random unitary evolution, while the inclusion of measurements significantly slows its growth down. For Floquet random circuits, we show that localized phases lead to reduced late-time saturation values of K-complexity, forbye we utilize these saturation values to probe the transition between thermal and many-body localized phases.
format Preprint
id arxiv_https___arxiv_org_abs_2409_03656
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Quantum complexity and localization in random and time-periodic unitary circuits
Sahu, Himanshu
Bhattacharya, Aranya
Nath, Pingal Pratyush
Quantum Physics
Disordered Systems and Neural Networks
Statistical Mechanics
Strongly Correlated Electrons
High Energy Physics - Theory
We study the growth and saturation of Krylov spread (K-) complexity under random quantum circuits. In Haar-random unitary evolution, we show that, for large system sizes, K-complexity grows linearly before saturating at a late-time value of $D/2$, where $D$ is the Hilbert space dimension, at timescales $\sim D$. Our numerical analysis encompasses two classes of random circuits: brick-wall random unitary circuits and Floquet random circuits. In brick-wall case, K-complexity exhibits dynamics consistent with Haar-random unitary evolution, while the inclusion of measurements significantly slows its growth down. For Floquet random circuits, we show that localized phases lead to reduced late-time saturation values of K-complexity, forbye we utilize these saturation values to probe the transition between thermal and many-body localized phases.
title Quantum complexity and localization in random and time-periodic unitary circuits
topic Quantum Physics
Disordered Systems and Neural Networks
Statistical Mechanics
Strongly Correlated Electrons
High Energy Physics - Theory
url https://arxiv.org/abs/2409.03656