Information scrambling and butterfly velocity in quantum spin glass chains

Fuente: arXiv
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Auteurs principaux: Y, Venkata Lokesh K., Bera, Surajit, Banerjee, Sumilan
Format: Preprint
Publié: 2024
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author Y, Venkata Lokesh K.
Bera, Surajit
Banerjee, Sumilan
author_facet Y, Venkata Lokesh K.
Bera, Surajit
Banerjee, Sumilan
contents We make lattice generalization of two well-known zero-dimensional models of quantum spin glass, Sachdev-Ye (SY) and spherical quantum $p$-spin glass model, to one dimension for studying crossovers in non-local scrambling dynamics due to glass transition, complex dynamics, and quantum and thermal fluctuations in paramagnetic (PM) and spin glass (SG) phases. In the SY chain of quantum dots, each described by infinite-range random Heisenberg model of $N$ spin-$S$ $SU(M)$ spins, we obtain the quantum Lyapunov exponent $λ_\mathrm{L}$ and butterfly velocity $v_B$ as a function of temperature $T$ and the quantum parameter $S$ across the PM-SG phase boundary using a bosonic spinon representation in the large $N,M$ limit. In particular, we extract asymptotic $T$ and $S$ dependence, e.g., power laws, for $λ_\mathrm{L}$ and $v_B$ in different regions deep inside the phases and near the replica symmetry breaking SG transition. We find the chaos to be non-maximal almost over the entire phase diagram. Very similar results for chaos indicators are found for the $p$-spin glass chain as a function of temperature and a suitable quantum parameter $Γ$, with some important qualitative differences. In particular, $λ_\mathrm{L}$ and $v_B$ exhibit a maximum, coinciding with onset of complex glassy relaxation, above the glass transition as a function of $T$ and $Γ$ in the PM phase of the $p$-spin glass model. In contrast, the maximum is only observed as a function of $S$, but not with temperature, in the PM phase of SY model. The maximum originates from enhanced chaos due to maximal complexity in the glassy landscape. Thus, the results in the SY model indicate very different evolution of glassy complexity with quantum and thermal fluctuations.
format Preprint
id arxiv_https___arxiv_org_abs_2401_04772
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Information scrambling and butterfly velocity in quantum spin glass chains
Y, Venkata Lokesh K.
Bera, Surajit
Banerjee, Sumilan
Disordered Systems and Neural Networks
Statistical Mechanics
Strongly Correlated Electrons
High Energy Physics - Theory
We make lattice generalization of two well-known zero-dimensional models of quantum spin glass, Sachdev-Ye (SY) and spherical quantum $p$-spin glass model, to one dimension for studying crossovers in non-local scrambling dynamics due to glass transition, complex dynamics, and quantum and thermal fluctuations in paramagnetic (PM) and spin glass (SG) phases. In the SY chain of quantum dots, each described by infinite-range random Heisenberg model of $N$ spin-$S$ $SU(M)$ spins, we obtain the quantum Lyapunov exponent $λ_\mathrm{L}$ and butterfly velocity $v_B$ as a function of temperature $T$ and the quantum parameter $S$ across the PM-SG phase boundary using a bosonic spinon representation in the large $N,M$ limit. In particular, we extract asymptotic $T$ and $S$ dependence, e.g., power laws, for $λ_\mathrm{L}$ and $v_B$ in different regions deep inside the phases and near the replica symmetry breaking SG transition. We find the chaos to be non-maximal almost over the entire phase diagram. Very similar results for chaos indicators are found for the $p$-spin glass chain as a function of temperature and a suitable quantum parameter $Γ$, with some important qualitative differences. In particular, $λ_\mathrm{L}$ and $v_B$ exhibit a maximum, coinciding with onset of complex glassy relaxation, above the glass transition as a function of $T$ and $Γ$ in the PM phase of the $p$-spin glass model. In contrast, the maximum is only observed as a function of $S$, but not with temperature, in the PM phase of SY model. The maximum originates from enhanced chaos due to maximal complexity in the glassy landscape. Thus, the results in the SY model indicate very different evolution of glassy complexity with quantum and thermal fluctuations.
title Information scrambling and butterfly velocity in quantum spin glass chains
topic Disordered Systems and Neural Networks
Statistical Mechanics
Strongly Correlated Electrons
High Energy Physics - Theory
url https://arxiv.org/abs/2401.04772