Quantum thermalization in a dimerized J1-J2 model

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Hauptverfasser: Mishra, Smitarani, Sahoo, Shaon
Format: Preprint
Veröffentlicht: 2025
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author Mishra, Smitarani
Sahoo, Shaon
author_facet Mishra, Smitarani
Sahoo, Shaon
contents We revisit the J1-J2 frustrated Heisenberg spin-1/2 chain with dimerization (δ) or modulation in the nearest-neighbor couplings to investigate its thermalization behavior. While the dimerization tends to induce localization, the next-nearest-neighbor interaction J2 generally favors thermalization, making the assessment of the model's compliance with the Eigenstate Thermalization Hypothesis (ETH) particularly subtle. The challenge is further compounded by the model's SU(2) symmetry; the study of ETH compliance is necessarily done for each symmetry sector but separating different sectors of this symmetry is known to be a computationally demanding task. The current study is driven by two main motivations: first, to explore whether the well-known ground-state phases of the model have any bearing on its thermalization properties; and second, to understand how the interplay between two competing factors, namely, the non-uniformity (via δ) and the beyond-nearest-neighbor interactions (via J2) governs the system's approach to thermal equilibrium. A systematic analysis shows that the ETH is most strongly satisfied for intermediate values of δ (~ 0.5) with J2 ranging from intermediate (~ 0.5) to large (~ 1)- a parameter regime falls within the spiral ground-state phase. It is also found that when the system is in the gapless ground-state phase (which falls within the N'eel phase), the ETH is more prone to violation. In the regime of large δ and small J2, the system is seen to enter a localized phase (characterized here by modulation in density-of-states; assessing ETH compliance is less meaningful for this phase.
format Preprint
id arxiv_https___arxiv_org_abs_2508_02398
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Quantum thermalization in a dimerized J1-J2 model
Mishra, Smitarani
Sahoo, Shaon
Statistical Mechanics
Quantum Physics
We revisit the J1-J2 frustrated Heisenberg spin-1/2 chain with dimerization (δ) or modulation in the nearest-neighbor couplings to investigate its thermalization behavior. While the dimerization tends to induce localization, the next-nearest-neighbor interaction J2 generally favors thermalization, making the assessment of the model's compliance with the Eigenstate Thermalization Hypothesis (ETH) particularly subtle. The challenge is further compounded by the model's SU(2) symmetry; the study of ETH compliance is necessarily done for each symmetry sector but separating different sectors of this symmetry is known to be a computationally demanding task. The current study is driven by two main motivations: first, to explore whether the well-known ground-state phases of the model have any bearing on its thermalization properties; and second, to understand how the interplay between two competing factors, namely, the non-uniformity (via δ) and the beyond-nearest-neighbor interactions (via J2) governs the system's approach to thermal equilibrium. A systematic analysis shows that the ETH is most strongly satisfied for intermediate values of δ (~ 0.5) with J2 ranging from intermediate (~ 0.5) to large (~ 1)- a parameter regime falls within the spiral ground-state phase. It is also found that when the system is in the gapless ground-state phase (which falls within the N'eel phase), the ETH is more prone to violation. In the regime of large δ and small J2, the system is seen to enter a localized phase (characterized here by modulation in density-of-states; assessing ETH compliance is less meaningful for this phase.
title Quantum thermalization in a dimerized J1-J2 model
topic Statistical Mechanics
Quantum Physics
url https://arxiv.org/abs/2508.02398