Krylov Delocalization/Localization across Ergodicity Breaking

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Hauptverfasser: Menzler, Heiko Georg, Jha, Rishabh
Format: Preprint
Veröffentlicht: 2024
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author Menzler, Heiko Georg
Jha, Rishabh
author_facet Menzler, Heiko Georg
Jha, Rishabh
contents Krylov complexity has recently gained attention where the growth of operator complexity in time is measured in terms of the off-diagonal operator Lanczos coefficients. The operator Lanczos algorithm reduces the problem of complexity growth to a single-particle semi-infinite tight-binding chain (known as the Krylov chain). Employing the phenomenon of Anderson localization, we propose the phenomenology of inverse localization length on the Krylov chain that undergoes delocalization/localization transition on the Krylov chain while the physical system undergoes ergodicity breaking. On the Krylov chain we find delocalization in an ergodic regime, as we show for the SYK model, and localization in case of a weakly ergodicity-broken regime. Considering the dynamics beyond scrambling, we find a collapse across different operators in the ergodic regime. We test for two settings: (1) the coupled SYK model, and (2) the quantum East model. Our findings open avenues for mapping ergodicity/weak ergodicity-breaking transitions to delocalization/localization phenomenology on the Krylov chain.
format Preprint
id arxiv_https___arxiv_org_abs_2403_14384
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Krylov Delocalization/Localization across Ergodicity Breaking
Menzler, Heiko Georg
Jha, Rishabh
Quantum Physics
Disordered Systems and Neural Networks
Strongly Correlated Electrons
High Energy Physics - Theory
Krylov complexity has recently gained attention where the growth of operator complexity in time is measured in terms of the off-diagonal operator Lanczos coefficients. The operator Lanczos algorithm reduces the problem of complexity growth to a single-particle semi-infinite tight-binding chain (known as the Krylov chain). Employing the phenomenon of Anderson localization, we propose the phenomenology of inverse localization length on the Krylov chain that undergoes delocalization/localization transition on the Krylov chain while the physical system undergoes ergodicity breaking. On the Krylov chain we find delocalization in an ergodic regime, as we show for the SYK model, and localization in case of a weakly ergodicity-broken regime. Considering the dynamics beyond scrambling, we find a collapse across different operators in the ergodic regime. We test for two settings: (1) the coupled SYK model, and (2) the quantum East model. Our findings open avenues for mapping ergodicity/weak ergodicity-breaking transitions to delocalization/localization phenomenology on the Krylov chain.
title Krylov Delocalization/Localization across Ergodicity Breaking
topic Quantum Physics
Disordered Systems and Neural Networks
Strongly Correlated Electrons
High Energy Physics - Theory
url https://arxiv.org/abs/2403.14384