Quantum Thermalization beyond Non-Integrability and Quantum Scars in a Multispecies Bose-Josephson Junction

Fuente: arXiv
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Main Authors: Di Menna, Francesco, Ciuchi, Sergio, Paganelli, Simone
Format: Preprint
Published: 2026
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author Di Menna, Francesco
Ciuchi, Sergio
Paganelli, Simone
author_facet Di Menna, Francesco
Ciuchi, Sergio
Paganelli, Simone
contents This work investigates the relationship between quantum chaos and thermalization in a three-species Bose-Josephson Junction (BJJ) with mutual interactions, without coupling to any external environment. The analysis is grounded in the Eigenstate Thermalization Hypothesis (ETH), the modern framework for quantum thermalization, in which non-integrability and chaos are historically assumed as prerequisites. After a thorough characterization of quantum chaos in this system, we examine the occurrence of thermal behavior expected when ETH holds. We identify three distinct regimes: chaotic, integrable, and separable. Remarkably, quantum thermalization occurs in both the chaotic and integrable regimes, while it breaks down in the separable limit - supporting that non-integrability is not a necessary condition for thermalization. Furthermore, since the system exhibits collective phenomena in the semiclassical limit, we identify athermal states in the chaotic regime classifiable as quantum scars, which show no signs of thermalization, consistently with a weak form of ETH. These findings contribute to the understanding of ergodicity breaking, emerging statistical behavior, and non-equilibrium dynamics in ultracold many-body quantum systems.
format Preprint
id arxiv_https___arxiv_org_abs_2603_25829
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Quantum Thermalization beyond Non-Integrability and Quantum Scars in a Multispecies Bose-Josephson Junction
Di Menna, Francesco
Ciuchi, Sergio
Paganelli, Simone
Statistical Mechanics
Quantum Gases
This work investigates the relationship between quantum chaos and thermalization in a three-species Bose-Josephson Junction (BJJ) with mutual interactions, without coupling to any external environment. The analysis is grounded in the Eigenstate Thermalization Hypothesis (ETH), the modern framework for quantum thermalization, in which non-integrability and chaos are historically assumed as prerequisites. After a thorough characterization of quantum chaos in this system, we examine the occurrence of thermal behavior expected when ETH holds. We identify three distinct regimes: chaotic, integrable, and separable. Remarkably, quantum thermalization occurs in both the chaotic and integrable regimes, while it breaks down in the separable limit - supporting that non-integrability is not a necessary condition for thermalization. Furthermore, since the system exhibits collective phenomena in the semiclassical limit, we identify athermal states in the chaotic regime classifiable as quantum scars, which show no signs of thermalization, consistently with a weak form of ETH. These findings contribute to the understanding of ergodicity breaking, emerging statistical behavior, and non-equilibrium dynamics in ultracold many-body quantum systems.
title Quantum Thermalization beyond Non-Integrability and Quantum Scars in a Multispecies Bose-Josephson Junction
topic Statistical Mechanics
Quantum Gases
url https://arxiv.org/abs/2603.25829