Automatic structural optimization of tree tensor networks

The tree tensor network (TTN) provides an essential theoretical framework for the practical simulation of quantum many-body systems, where the network structure defined by the connectivity of the isometry tensors plays a crucial role in improving its approximation accuracy. In this paper, we propose...

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Main Authors: Toshiya Hikihara, Hiroshi Ueda, Kouichi Okunishi, Kenji Harada, Tomotoshi Nishino
Format: Article
Language:English
Published: American Physical Society 2023-01-01
Series:Physical Review Research
Online Access:http://doi.org/10.1103/PhysRevResearch.5.013031
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author Toshiya Hikihara
Hiroshi Ueda
Kouichi Okunishi
Kenji Harada
Tomotoshi Nishino
author_facet Toshiya Hikihara
Hiroshi Ueda
Kouichi Okunishi
Kenji Harada
Tomotoshi Nishino
author_sort Toshiya Hikihara
collection DOAJ
description The tree tensor network (TTN) provides an essential theoretical framework for the practical simulation of quantum many-body systems, where the network structure defined by the connectivity of the isometry tensors plays a crucial role in improving its approximation accuracy. In this paper, we propose a TTN algorithm that enables us to automatically optimize the network structure by local reconnections of isometries to suppress the bipartite entanglement entropy on their legs. The algorithm can be seamlessly implemented to such a conventional TTN approach as the density-matrix renormalization group. We apply the algorithm to the inhomogeneous antiferromagnetic Heisenberg spin chain, having a hierarchical spatial distribution of the interactions. We then demonstrate that the entanglement structure embedded in the ground state of the system can be efficiently visualized as a perfect binary tree in the optimized TTN. Possible improvements and applications of the algorithm are also discussed.
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spelling doaj.art-d6bdf3a69b1247b990b64f543042e2412024-04-12T17:27:45ZengAmerican Physical SocietyPhysical Review Research2643-15642023-01-015101303110.1103/PhysRevResearch.5.013031Automatic structural optimization of tree tensor networksToshiya HikiharaHiroshi UedaKouichi OkunishiKenji HaradaTomotoshi NishinoThe tree tensor network (TTN) provides an essential theoretical framework for the practical simulation of quantum many-body systems, where the network structure defined by the connectivity of the isometry tensors plays a crucial role in improving its approximation accuracy. In this paper, we propose a TTN algorithm that enables us to automatically optimize the network structure by local reconnections of isometries to suppress the bipartite entanglement entropy on their legs. The algorithm can be seamlessly implemented to such a conventional TTN approach as the density-matrix renormalization group. We apply the algorithm to the inhomogeneous antiferromagnetic Heisenberg spin chain, having a hierarchical spatial distribution of the interactions. We then demonstrate that the entanglement structure embedded in the ground state of the system can be efficiently visualized as a perfect binary tree in the optimized TTN. Possible improvements and applications of the algorithm are also discussed.http://doi.org/10.1103/PhysRevResearch.5.013031
spellingShingle Toshiya Hikihara
Hiroshi Ueda
Kouichi Okunishi
Kenji Harada
Tomotoshi Nishino
Automatic structural optimization of tree tensor networks
Physical Review Research
title Automatic structural optimization of tree tensor networks
title_full Automatic structural optimization of tree tensor networks
title_fullStr Automatic structural optimization of tree tensor networks
title_full_unstemmed Automatic structural optimization of tree tensor networks
title_short Automatic structural optimization of tree tensor networks
title_sort automatic structural optimization of tree tensor networks
url http://doi.org/10.1103/PhysRevResearch.5.013031
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AT tomotoshinishino automaticstructuraloptimizationoftreetensornetworks