Quantum East Model: Localization, Nonthermal Eigenstates, and Slow Dynamics

We study in detail the properties of the quantum East model, an interacting quantum spin chain inspired by simple kinetically constrained models of classical glasses. Through a combination of analytics, exact diagonalization, and tensor-network methods, we show the existence of a transition, from a...

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Autores principales:	Nicola Pancotti, Giacomo Giudice, J. Ignacio Cirac, Juan P. Garrahan, Mari Carmen Bañuls
Formato:	article
Lenguaje:	EN
Publicado:	American Physical Society 2020
Materias:	Physics QC1-999
Acceso en línea:	https://doaj.org/article/fbd5e48aa24546718c8eb9ca4da22f65
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spelling	oai:doaj.org-article:fbd5e48aa24546718c8eb9ca4da22f652021-12-02T13:02:41ZQuantum East Model: Localization, Nonthermal Eigenstates, and Slow Dynamics10.1103/PhysRevX.10.0210512160-3308https://doaj.org/article/fbd5e48aa24546718c8eb9ca4da22f652020-06-01T00:00:00Zhttp://doi.org/10.1103/PhysRevX.10.021051http://doi.org/10.1103/PhysRevX.10.021051https://doaj.org/toc/2160-3308We study in detail the properties of the quantum East model, an interacting quantum spin chain inspired by simple kinetically constrained models of classical glasses. Through a combination of analytics, exact diagonalization, and tensor-network methods, we show the existence of a transition, from a fast to a slow thermalization regime, which manifests itself throughout the spectrum. On the slow side, by exploiting the localization of the ground state and the form of the Hamiltonian, we explicitly construct a large (exponential in size) number of nonthermal states that become exact finite-energy-density eigenstates in the large size limit, as expected for a true phase transition. A “superspin” generalization allows us to find a further large class of area-law states proved to display very slow relaxation. These states retain memory of their initial conditions for extremely long times. Our numerical analysis reveals that the localization properties are not limited to the ground state and that many eigenstates have large overlap with product states and can be approximated well by matrix product states at arbitrary energy densities. The mechanism that induces localization to the ground state, and hence the nonthermal behavior of the system, can be extended to a wide range of models including a number of simple spin chains. We discuss implications of our results for slow thermalization and nonergodicity more generally in disorder-free systems with constraints, and we give numerical evidence that these results may be extended to two-dimensional systems.Nicola PancottiGiacomo GiudiceJ. Ignacio CiracJuan P. GarrahanMari Carmen BañulsAmerican Physical SocietyarticlePhysicsQC1-999ENPhysical Review X, Vol 10, Iss 2, p 021051 (2020)
institution	DOAJ
collection	DOAJ
language	EN
topic	Physics QC1-999
spellingShingle	Physics QC1-999 Nicola Pancotti Giacomo Giudice J. Ignacio Cirac Juan P. Garrahan Mari Carmen Bañuls Quantum East Model: Localization, Nonthermal Eigenstates, and Slow Dynamics
description	We study in detail the properties of the quantum East model, an interacting quantum spin chain inspired by simple kinetically constrained models of classical glasses. Through a combination of analytics, exact diagonalization, and tensor-network methods, we show the existence of a transition, from a fast to a slow thermalization regime, which manifests itself throughout the spectrum. On the slow side, by exploiting the localization of the ground state and the form of the Hamiltonian, we explicitly construct a large (exponential in size) number of nonthermal states that become exact finite-energy-density eigenstates in the large size limit, as expected for a true phase transition. A “superspin” generalization allows us to find a further large class of area-law states proved to display very slow relaxation. These states retain memory of their initial conditions for extremely long times. Our numerical analysis reveals that the localization properties are not limited to the ground state and that many eigenstates have large overlap with product states and can be approximated well by matrix product states at arbitrary energy densities. The mechanism that induces localization to the ground state, and hence the nonthermal behavior of the system, can be extended to a wide range of models including a number of simple spin chains. We discuss implications of our results for slow thermalization and nonergodicity more generally in disorder-free systems with constraints, and we give numerical evidence that these results may be extended to two-dimensional systems.
format	article
author	Nicola Pancotti Giacomo Giudice J. Ignacio Cirac Juan P. Garrahan Mari Carmen Bañuls
author_facet	Nicola Pancotti Giacomo Giudice J. Ignacio Cirac Juan P. Garrahan Mari Carmen Bañuls
author_sort	Nicola Pancotti
title	Quantum East Model: Localization, Nonthermal Eigenstates, and Slow Dynamics
title_short	Quantum East Model: Localization, Nonthermal Eigenstates, and Slow Dynamics
title_full	Quantum East Model: Localization, Nonthermal Eigenstates, and Slow Dynamics
title_fullStr	Quantum East Model: Localization, Nonthermal Eigenstates, and Slow Dynamics
title_full_unstemmed	Quantum East Model: Localization, Nonthermal Eigenstates, and Slow Dynamics
title_sort	quantum east model: localization, nonthermal eigenstates, and slow dynamics
publisher	American Physical Society
publishDate	2020
url	https://doaj.org/article/fbd5e48aa24546718c8eb9ca4da22f65
work_keys_str_mv	AT nicolapancotti quantumeastmodellocalizationnonthermaleigenstatesandslowdynamics AT giacomogiudice quantumeastmodellocalizationnonthermaleigenstatesandslowdynamics AT jignaciocirac quantumeastmodellocalizationnonthermaleigenstatesandslowdynamics AT juanpgarrahan quantumeastmodellocalizationnonthermaleigenstatesandslowdynamics AT maricarmenbanuls quantumeastmodellocalizationnonthermaleigenstatesandslowdynamics
_version_	1718393543969472512

Quantum East Model: Localization, Nonthermal Eigenstates, and Slow Dynamics

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