Spread complexity and localization in $\mathcal{PT}$-symmetric systems

Fuente: arXiv
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Autores principales: Bhattacharya, Aranya, Das, Rathindra Nath, Dey, Bidyut, Erdmenger, Johanna
Formato: Preprint
Publicado: 2024
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author Bhattacharya, Aranya
Das, Rathindra Nath
Dey, Bidyut
Erdmenger, Johanna
author_facet Bhattacharya, Aranya
Das, Rathindra Nath
Dey, Bidyut
Erdmenger, Johanna
contents We present a framework for investigating wave function spreading in $\mathcal{PT}$-symmetric quantum systems using spread complexity and spread entropy. We consider a tight-binding chain with complex on-site potentials at the boundary sites. In the $\mathcal{PT}$-unbroken phase, the wave function is delocalized. We find that in the $\mathcal{PT}$-broken phase, it becomes localized on one edge of the tight-binding lattice. This localization is a realization of the non-Hermitian skin effect. Localization in the $\mathcal{PT}$-broken phase is observed both in the lattice chain basis and the Krylov basis. Spread entropy, entropic complexity, and a further measure that we term the Krylov inverse participation ratio probe the dynamics of wave function spreading and quantify the strength of localization probed in the Krylov basis. The number of Krylov basis vectors required to store the information of the state reduces with the strength of localization. Our results demonstrate how measures in Krylov space can be used to characterize the non-hermitian skin effect and its localization phase transition.
format Preprint
id arxiv_https___arxiv_org_abs_2406_03524
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Spread complexity and localization in $\mathcal{PT}$-symmetric systems
Bhattacharya, Aranya
Das, Rathindra Nath
Dey, Bidyut
Erdmenger, Johanna
High Energy Physics - Theory
Statistical Mechanics
Quantum Physics
We present a framework for investigating wave function spreading in $\mathcal{PT}$-symmetric quantum systems using spread complexity and spread entropy. We consider a tight-binding chain with complex on-site potentials at the boundary sites. In the $\mathcal{PT}$-unbroken phase, the wave function is delocalized. We find that in the $\mathcal{PT}$-broken phase, it becomes localized on one edge of the tight-binding lattice. This localization is a realization of the non-Hermitian skin effect. Localization in the $\mathcal{PT}$-broken phase is observed both in the lattice chain basis and the Krylov basis. Spread entropy, entropic complexity, and a further measure that we term the Krylov inverse participation ratio probe the dynamics of wave function spreading and quantify the strength of localization probed in the Krylov basis. The number of Krylov basis vectors required to store the information of the state reduces with the strength of localization. Our results demonstrate how measures in Krylov space can be used to characterize the non-hermitian skin effect and its localization phase transition.
title Spread complexity and localization in $\mathcal{PT}$-symmetric systems
topic High Energy Physics - Theory
Statistical Mechanics
Quantum Physics
url https://arxiv.org/abs/2406.03524