Temporal Entanglement in Chaotic Quantum Circuits

The concept of space evolution (or space-time duality) has emerged as a promising approach for studying quantum dynamics. The basic idea involves exchanging the roles of space and time, evolving the system using a space transfer matrix rather than the time evolution operator. The infinite-volume lim...

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Main Authors: Alessandro Foligno, Tianci Zhou, Bruno Bertini
Format: Article
Language:English
Published: American Physical Society 2023-10-01
Series:Physical Review X
Online Access:http://doi.org/10.1103/PhysRevX.13.041008
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author Alessandro Foligno
Tianci Zhou
Bruno Bertini
author_facet Alessandro Foligno
Tianci Zhou
Bruno Bertini
author_sort Alessandro Foligno
collection DOAJ
description The concept of space evolution (or space-time duality) has emerged as a promising approach for studying quantum dynamics. The basic idea involves exchanging the roles of space and time, evolving the system using a space transfer matrix rather than the time evolution operator. The infinite-volume limit is then described by the fixed points of the latter transfer matrix, also known as influence matrices. To establish the potential of this method as a bona fide computational scheme, it is important to understand whether the influence matrices can be efficiently encoded in a classical computer. Here we begin this quest by presenting a systematic characterization of their entanglement—dubbed temporal entanglement—in chaotic quantum systems. We consider the most general form of space evolution, i.e., evolution in a generic spacelike direction, and present two fundamental results. First, we show that temporal entanglement always follows a volume law in time. Second, we identify two marginal cases—(i) pure space evolution in generic chaotic systems and (ii) any spacelike evolution in dual-unitary circuits—where Rényi entropies with index larger than one are sublinear in time while the von Neumann entanglement entropy grows linearly. We attribute this behavior to the existence of a product state with large overlap with the influence matrices. This unexpected structure in the temporal entanglement spectrum might be the key to an efficient computational implementation of the space evolution.
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spelling doaj.art-c4bb3d0e25a14031802843ac04f15a062023-10-11T17:55:33ZengAmerican Physical SocietyPhysical Review X2160-33082023-10-0113404100810.1103/PhysRevX.13.041008Temporal Entanglement in Chaotic Quantum CircuitsAlessandro FolignoTianci ZhouBruno BertiniThe concept of space evolution (or space-time duality) has emerged as a promising approach for studying quantum dynamics. The basic idea involves exchanging the roles of space and time, evolving the system using a space transfer matrix rather than the time evolution operator. The infinite-volume limit is then described by the fixed points of the latter transfer matrix, also known as influence matrices. To establish the potential of this method as a bona fide computational scheme, it is important to understand whether the influence matrices can be efficiently encoded in a classical computer. Here we begin this quest by presenting a systematic characterization of their entanglement—dubbed temporal entanglement—in chaotic quantum systems. We consider the most general form of space evolution, i.e., evolution in a generic spacelike direction, and present two fundamental results. First, we show that temporal entanglement always follows a volume law in time. Second, we identify two marginal cases—(i) pure space evolution in generic chaotic systems and (ii) any spacelike evolution in dual-unitary circuits—where Rényi entropies with index larger than one are sublinear in time while the von Neumann entanglement entropy grows linearly. We attribute this behavior to the existence of a product state with large overlap with the influence matrices. This unexpected structure in the temporal entanglement spectrum might be the key to an efficient computational implementation of the space evolution.http://doi.org/10.1103/PhysRevX.13.041008
spellingShingle Alessandro Foligno
Tianci Zhou
Bruno Bertini
Temporal Entanglement in Chaotic Quantum Circuits
Physical Review X
title Temporal Entanglement in Chaotic Quantum Circuits
title_full Temporal Entanglement in Chaotic Quantum Circuits
title_fullStr Temporal Entanglement in Chaotic Quantum Circuits
title_full_unstemmed Temporal Entanglement in Chaotic Quantum Circuits
title_short Temporal Entanglement in Chaotic Quantum Circuits
title_sort temporal entanglement in chaotic quantum circuits
url http://doi.org/10.1103/PhysRevX.13.041008
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