Two-dimensional quantum breakdown model with Krylov subspace many-body localization

Fuente: arXiv
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Main Authors: Liu, Xinyu, Lian, Biao
Format: Preprint
Published: 2023
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author Liu, Xinyu
Lian, Biao
author_facet Liu, Xinyu
Lian, Biao
contents We propose a two-dimensional (2d) quantum breakdown model of hardcore bosons interacting with disordered spins which would be classical without the bosons. It resembles particles incident into supersaturated vapor. The model exhibits a set of subsystem symmetries, and has a strong fragmentation into Krylov subspaces in each symmetry sector. The Hamiltonian in each Krylov subspace maps to a single-particle problem in a Cayley tree-like graph. At zero disorder, the Krylov subspaces exhibit either (possible) integrable features, or quantum chaos with quantum scar states showing irregular energy and degeneracy patterns. At nonzero disorders, they enter a 2d many-body localization (MBL) phase beyond certain disorder strength $W_*$, as indicated by Poisson level spacing statistics and entanglement entropy growing as $\log t$ with time $t$. Our theoretical arguments suggest $W_*$ is finite or zero for boson number $N_b\lesssim L^γ/\log L$ ($1/2\le γ\le 1$) as system size $L\rightarrow\infty$. This gives a more stringent condition for MBL than that in the 1d quantum breakdown models. This model reveals the possibility of MBL in systems of quantum particles interacting with classical degrees of freedom.
format Preprint
id arxiv_https___arxiv_org_abs_2311_10968
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Two-dimensional quantum breakdown model with Krylov subspace many-body localization
Liu, Xinyu
Lian, Biao
Strongly Correlated Electrons
Disordered Systems and Neural Networks
Quantum Gases
Statistical Mechanics
We propose a two-dimensional (2d) quantum breakdown model of hardcore bosons interacting with disordered spins which would be classical without the bosons. It resembles particles incident into supersaturated vapor. The model exhibits a set of subsystem symmetries, and has a strong fragmentation into Krylov subspaces in each symmetry sector. The Hamiltonian in each Krylov subspace maps to a single-particle problem in a Cayley tree-like graph. At zero disorder, the Krylov subspaces exhibit either (possible) integrable features, or quantum chaos with quantum scar states showing irregular energy and degeneracy patterns. At nonzero disorders, they enter a 2d many-body localization (MBL) phase beyond certain disorder strength $W_*$, as indicated by Poisson level spacing statistics and entanglement entropy growing as $\log t$ with time $t$. Our theoretical arguments suggest $W_*$ is finite or zero for boson number $N_b\lesssim L^γ/\log L$ ($1/2\le γ\le 1$) as system size $L\rightarrow\infty$. This gives a more stringent condition for MBL than that in the 1d quantum breakdown models. This model reveals the possibility of MBL in systems of quantum particles interacting with classical degrees of freedom.
title Two-dimensional quantum breakdown model with Krylov subspace many-body localization
topic Strongly Correlated Electrons
Disordered Systems and Neural Networks
Quantum Gases
Statistical Mechanics
url https://arxiv.org/abs/2311.10968