Ensemble Inequivalence in Long-Range Quantum Spin Systems

Fuente: arXiv
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Autori principali: Arrufat-Vicente, Daniel, Mukamel, David, Ruffo, Stefano, Defenu, Nicolo
Natura: Preprint
Pubblicazione: 2025
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author Arrufat-Vicente, Daniel
Mukamel, David
Ruffo, Stefano
Defenu, Nicolo
author_facet Arrufat-Vicente, Daniel
Mukamel, David
Ruffo, Stefano
Defenu, Nicolo
contents Ensemble inequivalence occurs when a systems thermodynamic properties vary depending on the statistical ensemble used to describe it. This phenomenon is known to happen in systems with long-range interactions and has been observed in many classical systems. In this study, we provide a detailed analysis of a long-range quantum ferromagnet spin model that exhibits ensemble inequivalence. At zero temperature ($T = 0$), the microcanonical phase diagram matches that of the canonical ensemble. However, the two ensembles yield different phase diagrams at finite temperatures. This behavior contrasts with the conventional understanding in statistical mechanics of systems with short-range interactions, where thermodynamic properties are expected to align across different ensembles in the thermodynamic limit. We discuss the implications of these findings for synthetic quantum long-range platforms, such as atomic, molecular, and optical (AMO) systems.
format Preprint
id arxiv_https___arxiv_org_abs_2504_14008
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Ensemble Inequivalence in Long-Range Quantum Spin Systems
Arrufat-Vicente, Daniel
Mukamel, David
Ruffo, Stefano
Defenu, Nicolo
Statistical Mechanics
Ensemble inequivalence occurs when a systems thermodynamic properties vary depending on the statistical ensemble used to describe it. This phenomenon is known to happen in systems with long-range interactions and has been observed in many classical systems. In this study, we provide a detailed analysis of a long-range quantum ferromagnet spin model that exhibits ensemble inequivalence. At zero temperature ($T = 0$), the microcanonical phase diagram matches that of the canonical ensemble. However, the two ensembles yield different phase diagrams at finite temperatures. This behavior contrasts with the conventional understanding in statistical mechanics of systems with short-range interactions, where thermodynamic properties are expected to align across different ensembles in the thermodynamic limit. We discuss the implications of these findings for synthetic quantum long-range platforms, such as atomic, molecular, and optical (AMO) systems.
title Ensemble Inequivalence in Long-Range Quantum Spin Systems
topic Statistical Mechanics
url https://arxiv.org/abs/2504.14008