Exact critical exponents of the Motzkin and Fredkin Chains

Fuente: arXiv
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Main Authors: Mykland, Olai B., Zhang, Zhao
Format: Preprint
Published: 2025
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author Mykland, Olai B.
Zhang, Zhao
author_facet Mykland, Olai B.
Zhang, Zhao
contents The Motzkin and Fredkin chains are frustration-free models with exactly solvable ground states. Their $q$-deformations describe an exotic quantum phase transition from a disordered phase to an ordered one subject to domain-wall boundary conditions. Understanding of this phase transition has so far been mainly focused on the entanglement scaling and spectral gap properties, especially for versions of the models enriched with a color degree of freedom. Although the ground states can be exactly represented as a holographic tensor network resembling the multiscale entanglement renormalization ansatz at the critical point, the lack of unitary and isometric tensors in the hierarchical network hinders the characterization of the critical behaviors. Using instead the transfer matrix (TM) obtained from the matrix product state (MPS) representation combined with a renormalization group analysis, we analytically compute the critical exponents $η=1/2$ and $ν_\pm=2/3$, revealing a duality between the ordered and disordered phases. The exact critical exponents are verified numerically by MPS calculations and numerical diagonalization of the TM.
format Preprint
id arxiv_https___arxiv_org_abs_2507_14656
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Exact critical exponents of the Motzkin and Fredkin Chains
Mykland, Olai B.
Zhang, Zhao
Strongly Correlated Electrons
Statistical Mechanics
High Energy Physics - Theory
Mathematical Physics
Quantum Physics
The Motzkin and Fredkin chains are frustration-free models with exactly solvable ground states. Their $q$-deformations describe an exotic quantum phase transition from a disordered phase to an ordered one subject to domain-wall boundary conditions. Understanding of this phase transition has so far been mainly focused on the entanglement scaling and spectral gap properties, especially for versions of the models enriched with a color degree of freedom. Although the ground states can be exactly represented as a holographic tensor network resembling the multiscale entanglement renormalization ansatz at the critical point, the lack of unitary and isometric tensors in the hierarchical network hinders the characterization of the critical behaviors. Using instead the transfer matrix (TM) obtained from the matrix product state (MPS) representation combined with a renormalization group analysis, we analytically compute the critical exponents $η=1/2$ and $ν_\pm=2/3$, revealing a duality between the ordered and disordered phases. The exact critical exponents are verified numerically by MPS calculations and numerical diagonalization of the TM.
title Exact critical exponents of the Motzkin and Fredkin Chains
topic Strongly Correlated Electrons
Statistical Mechanics
High Energy Physics - Theory
Mathematical Physics
Quantum Physics
url https://arxiv.org/abs/2507.14656