Krylov Complexity Under Hamiltonian Deformations and Toda Flows

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Autori principali: Takahashi, Kazutaka, Nandy, Pratik, del Campo, Adolfo
Natura: Preprint
Pubblicazione: 2025
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author Takahashi, Kazutaka
Nandy, Pratik
del Campo, Adolfo
author_facet Takahashi, Kazutaka
Nandy, Pratik
del Campo, Adolfo
contents The quantum dynamics of a complex system can be efficiently described in Krylov space, the minimal subspace in which the dynamics unfolds. We apply the Krylov subspace method for Hamiltonian deformations, which provides a systematic way of constructing solvable models from known instances. In doing so, we relate the evolution of deformed and undeformed theories and investigate their complexity. For a certain class of deformations, the resulting Krylov subspace is unchanged, and we observe time evolutions with a reorganized basis. The tridiagonal form of the generator in the Krylov space is maintained, and we obtain generalized Toda equations as a function of the deformation parameters. The imaginary-time-like evolutions can be described by real-time unitary ones. As possible applications, we discuss coherent Gibbs states for thermodynamic systems, for which we analyze the survival probability, spread complexity, Krylov entropy, and associated time-averaged quantities. We further discuss the statistical properties of random matrices and supersymmetric systems for quadratic deformations.
format Preprint
id arxiv_https___arxiv_org_abs_2510_19436
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Krylov Complexity Under Hamiltonian Deformations and Toda Flows
Takahashi, Kazutaka
Nandy, Pratik
del Campo, Adolfo
Quantum Physics
Statistical Mechanics
High Energy Physics - Theory
The quantum dynamics of a complex system can be efficiently described in Krylov space, the minimal subspace in which the dynamics unfolds. We apply the Krylov subspace method for Hamiltonian deformations, which provides a systematic way of constructing solvable models from known instances. In doing so, we relate the evolution of deformed and undeformed theories and investigate their complexity. For a certain class of deformations, the resulting Krylov subspace is unchanged, and we observe time evolutions with a reorganized basis. The tridiagonal form of the generator in the Krylov space is maintained, and we obtain generalized Toda equations as a function of the deformation parameters. The imaginary-time-like evolutions can be described by real-time unitary ones. As possible applications, we discuss coherent Gibbs states for thermodynamic systems, for which we analyze the survival probability, spread complexity, Krylov entropy, and associated time-averaged quantities. We further discuss the statistical properties of random matrices and supersymmetric systems for quadratic deformations.
title Krylov Complexity Under Hamiltonian Deformations and Toda Flows
topic Quantum Physics
Statistical Mechanics
High Energy Physics - Theory
url https://arxiv.org/abs/2510.19436