Matrix-product unitaries: Beyond quantum cellular automata

Matrix-product unitaries (MPU) are 1D tensor networks describing time evolution and unitary symmetries of quantum systems, while their action on states by construction preserves the entanglement area law. MPU which are formed by a single repeated tensor are known to coincide with 1D quantum cellular...

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Main Authors: Georgios Styliaris, Rahul Trivedi, David Perez-Garcia, J. Ignacio Cirac
Format: Article
Language:English
Published: Verein zur Förderung des Open Access Publizierens in den Quantenwissenschaften 2025-02-01
Series:Quantum
Online Access:https://quantum-journal.org/papers/q-2025-02-25-1645/pdf/
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author Georgios Styliaris
Rahul Trivedi
David Perez-Garcia
J. Ignacio Cirac
author_facet Georgios Styliaris
Rahul Trivedi
David Perez-Garcia
J. Ignacio Cirac
author_sort Georgios Styliaris
collection DOAJ
description Matrix-product unitaries (MPU) are 1D tensor networks describing time evolution and unitary symmetries of quantum systems, while their action on states by construction preserves the entanglement area law. MPU which are formed by a single repeated tensor are known to coincide with 1D quantum cellular automata (QCA), i.e., unitaries with an exact light cone. However, this correspondence breaks down for MPU with open boundary conditions, even if the resulting operator is translation-invariant. Such unitaries can turn short- to long-range correlations and thus alter the underlying phase of matter. Here we make the first steps towards a theory of MPU with uniform bulk but arbitrary boundary. In particular, we study the structure of a subclass with a direct-sum form which maximally violates the QCA property. We also consider the general case of MPU formed by site-dependent (nonuniform) tensors and show a correspondence between MPU and locally maximally entanglable states.
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spelling doaj-art-feb4c75b5d3e4c3b8a9ac2a29df12bc22025-08-20T02:04:09ZengVerein zur Förderung des Open Access Publizierens in den QuantenwissenschaftenQuantum2521-327X2025-02-019164510.22331/q-2025-02-25-164510.22331/q-2025-02-25-1645Matrix-product unitaries: Beyond quantum cellular automataGeorgios StyliarisRahul TrivediDavid Perez-GarciaJ. Ignacio CiracMatrix-product unitaries (MPU) are 1D tensor networks describing time evolution and unitary symmetries of quantum systems, while their action on states by construction preserves the entanglement area law. MPU which are formed by a single repeated tensor are known to coincide with 1D quantum cellular automata (QCA), i.e., unitaries with an exact light cone. However, this correspondence breaks down for MPU with open boundary conditions, even if the resulting operator is translation-invariant. Such unitaries can turn short- to long-range correlations and thus alter the underlying phase of matter. Here we make the first steps towards a theory of MPU with uniform bulk but arbitrary boundary. In particular, we study the structure of a subclass with a direct-sum form which maximally violates the QCA property. We also consider the general case of MPU formed by site-dependent (nonuniform) tensors and show a correspondence between MPU and locally maximally entanglable states.https://quantum-journal.org/papers/q-2025-02-25-1645/pdf/
spellingShingle Georgios Styliaris
Rahul Trivedi
David Perez-Garcia
J. Ignacio Cirac
Matrix-product unitaries: Beyond quantum cellular automata
Quantum
title Matrix-product unitaries: Beyond quantum cellular automata
title_full Matrix-product unitaries: Beyond quantum cellular automata
title_fullStr Matrix-product unitaries: Beyond quantum cellular automata
title_full_unstemmed Matrix-product unitaries: Beyond quantum cellular automata
title_short Matrix-product unitaries: Beyond quantum cellular automata
title_sort matrix product unitaries beyond quantum cellular automata
url https://quantum-journal.org/papers/q-2025-02-25-1645/pdf/
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AT rahultrivedi matrixproductunitariesbeyondquantumcellularautomata
AT davidperezgarcia matrixproductunitariesbeyondquantumcellularautomata
AT jignaciocirac matrixproductunitariesbeyondquantumcellularautomata