Detection of 2D SPT phases under decoherence

Fuente: arXiv
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Autores principales: Manjunath, Naren, Turzillo, Alex, Wang, Chong
Formato: Preprint
Publicado: 2025
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author Manjunath, Naren
Turzillo, Alex
Wang, Chong
author_facet Manjunath, Naren
Turzillo, Alex
Wang, Chong
contents We propose a bulk order parameter for extracting symmetry-protected topological (SPT) invariants of quantum many-body mixed states on a two dimensional lattice using partial symmetries. The procedure builds on the partial symmetry order parameter recently developed by some of the authors to study SPT phases of pure states and adapts them to the decohered setting. For a symmetry $G = E \times A$ where $E$ is a strong symmetry and $A$ is a weak symmetry, we show that the partial symmetry order parameter detects SPT invariants jointly protected by $E$ and $A$. We demonstrate this explicitly using a class of mixed states obtained from CZX-type models with $\mathbb{Z}_2\times\mathbb{Z}_2$ symmetry and subjecting them to noise that weakens one of the $\mathbb{Z}_2$ symmetries. We also comment on the practical detection of SPT invariants in quantum simulators through randomized measurements.
format Preprint
id arxiv_https___arxiv_org_abs_2507_00127
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Detection of 2D SPT phases under decoherence
Manjunath, Naren
Turzillo, Alex
Wang, Chong
Strongly Correlated Electrons
Quantum Physics
We propose a bulk order parameter for extracting symmetry-protected topological (SPT) invariants of quantum many-body mixed states on a two dimensional lattice using partial symmetries. The procedure builds on the partial symmetry order parameter recently developed by some of the authors to study SPT phases of pure states and adapts them to the decohered setting. For a symmetry $G = E \times A$ where $E$ is a strong symmetry and $A$ is a weak symmetry, we show that the partial symmetry order parameter detects SPT invariants jointly protected by $E$ and $A$. We demonstrate this explicitly using a class of mixed states obtained from CZX-type models with $\mathbb{Z}_2\times\mathbb{Z}_2$ symmetry and subjecting them to noise that weakens one of the $\mathbb{Z}_2$ symmetries. We also comment on the practical detection of SPT invariants in quantum simulators through randomized measurements.
title Detection of 2D SPT phases under decoherence
topic Strongly Correlated Electrons
Quantum Physics
url https://arxiv.org/abs/2507.00127