Hierarchy of Linear Light Cones with Long-Range Interactions

In quantum many-body systems with local interactions, quantum information and entanglement cannot spread outside of a linear light cone, which expands at an emergent velocity analogous to the speed of light. Local operations at sufficiently separated spacetime points approximately commute—given a ma...

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Autores principales: Minh C. Tran, Chi-Fang Chen, Adam Ehrenberg, Andrew Y. Guo, Abhinav Deshpande, Yifan Hong, Zhe-Xuan Gong, Alexey V. Gorshkov, Andrew Lucas
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Publicado: American Physical Society 2020
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spelling oai:doaj.org-article:5a6be182fb564d49a2d8df81385553ca2021-12-02T11:11:32ZHierarchy of Linear Light Cones with Long-Range Interactions10.1103/PhysRevX.10.0310092160-3308https://doaj.org/article/5a6be182fb564d49a2d8df81385553ca2020-07-01T00:00:00Zhttp://doi.org/10.1103/PhysRevX.10.031009http://doi.org/10.1103/PhysRevX.10.031009https://doaj.org/toc/2160-3308In quantum many-body systems with local interactions, quantum information and entanglement cannot spread outside of a linear light cone, which expands at an emergent velocity analogous to the speed of light. Local operations at sufficiently separated spacetime points approximately commute—given a many-body state |ψ⟩, O_{x}(t)O_{y}|ψ⟩≈O_{y}O_{x}(t)|ψ⟩ with arbitrarily small errors—so long as |x-y|≳vt, where v is finite. Yet, most nonrelativistic physical systems realized in nature have long-range interactions: Two degrees of freedom separated by a distance r interact with potential energy V(r)∝1/r^{α}. In systems with long-range interactions, we rigorously establish a hierarchy of linear light cones: At the same α, some quantum information processing tasks are constrained by a linear light cone, while others are not. In one spatial dimension, this linear light cone exists for every many-body state |ψ⟩ when α>3 (Lieb-Robinson light cone); for a typical state |ψ⟩ chosen uniformly at random from the Hilbert space when α>5/2 (Frobenius light cone); and for every state of a noninteracting system when α>2 (free light cone). These bounds apply to time-dependent systems and are optimal up to subalgebraic improvements. Our theorems regarding the Lieb-Robinson and free light cones—and their tightness—also generalize to arbitrary dimensions. We discuss the implications of our bounds on the growth of connected correlators and of topological order, the clustering of correlations in gapped systems, and the digital simulation of systems with long-range interactions. In addition, we show that universal quantum state transfer, as well as many-body quantum chaos, is bounded by the Frobenius light cone and, therefore, is poorly constrained by all Lieb-Robinson bounds.Minh C. TranChi-Fang ChenAdam EhrenbergAndrew Y. GuoAbhinav DeshpandeYifan HongZhe-Xuan GongAlexey V. GorshkovAndrew LucasAmerican Physical SocietyarticlePhysicsQC1-999ENPhysical Review X, Vol 10, Iss 3, p 031009 (2020)
institution DOAJ
collection DOAJ
language EN
topic Physics
QC1-999
spellingShingle Physics
QC1-999
Minh C. Tran
Chi-Fang Chen
Adam Ehrenberg
Andrew Y. Guo
Abhinav Deshpande
Yifan Hong
Zhe-Xuan Gong
Alexey V. Gorshkov
Andrew Lucas
Hierarchy of Linear Light Cones with Long-Range Interactions
description In quantum many-body systems with local interactions, quantum information and entanglement cannot spread outside of a linear light cone, which expands at an emergent velocity analogous to the speed of light. Local operations at sufficiently separated spacetime points approximately commute—given a many-body state |ψ⟩, O_{x}(t)O_{y}|ψ⟩≈O_{y}O_{x}(t)|ψ⟩ with arbitrarily small errors—so long as |x-y|≳vt, where v is finite. Yet, most nonrelativistic physical systems realized in nature have long-range interactions: Two degrees of freedom separated by a distance r interact with potential energy V(r)∝1/r^{α}. In systems with long-range interactions, we rigorously establish a hierarchy of linear light cones: At the same α, some quantum information processing tasks are constrained by a linear light cone, while others are not. In one spatial dimension, this linear light cone exists for every many-body state |ψ⟩ when α>3 (Lieb-Robinson light cone); for a typical state |ψ⟩ chosen uniformly at random from the Hilbert space when α>5/2 (Frobenius light cone); and for every state of a noninteracting system when α>2 (free light cone). These bounds apply to time-dependent systems and are optimal up to subalgebraic improvements. Our theorems regarding the Lieb-Robinson and free light cones—and their tightness—also generalize to arbitrary dimensions. We discuss the implications of our bounds on the growth of connected correlators and of topological order, the clustering of correlations in gapped systems, and the digital simulation of systems with long-range interactions. In addition, we show that universal quantum state transfer, as well as many-body quantum chaos, is bounded by the Frobenius light cone and, therefore, is poorly constrained by all Lieb-Robinson bounds.
format article
author Minh C. Tran
Chi-Fang Chen
Adam Ehrenberg
Andrew Y. Guo
Abhinav Deshpande
Yifan Hong
Zhe-Xuan Gong
Alexey V. Gorshkov
Andrew Lucas
author_facet Minh C. Tran
Chi-Fang Chen
Adam Ehrenberg
Andrew Y. Guo
Abhinav Deshpande
Yifan Hong
Zhe-Xuan Gong
Alexey V. Gorshkov
Andrew Lucas
author_sort Minh C. Tran
title Hierarchy of Linear Light Cones with Long-Range Interactions
title_short Hierarchy of Linear Light Cones with Long-Range Interactions
title_full Hierarchy of Linear Light Cones with Long-Range Interactions
title_fullStr Hierarchy of Linear Light Cones with Long-Range Interactions
title_full_unstemmed Hierarchy of Linear Light Cones with Long-Range Interactions
title_sort hierarchy of linear light cones with long-range interactions
publisher American Physical Society
publishDate 2020
url https://doaj.org/article/5a6be182fb564d49a2d8df81385553ca
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