Bose-Einstein Condensation, Fluctuations and Spontaneous Symmetry Breaking

Fuente: arXiv
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Main Authors: Crisanti, A., Sarracino, A., Zannetti, M.
Format: Preprint
Published: 2025
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_version_ 1866910046535811072
author Crisanti, A.
Sarracino, A.
Zannetti, M.
author_facet Crisanti, A.
Sarracino, A.
Zannetti, M.
contents The realisation of Bose-Einstein condensation under grand-canonical conditions has provided the experimental evidence for the simultaneous occurrence of macroscopic fluctuations and phase coherence of the condensate. The observation of these two features, against a consolidated tradition which wants the fluctuations to be pathological (grand-canonical catastrophe) and incompatible with spontaneous symmetry braking, calls for a comprehensive rethinking of the approach to the problem. In this paper we consider the uniform ideal gas in a box and we present an alternative conceptual framework. We show that the usually-employed Bogoliubov quasi-average construction fails to reproduce the broken-symmetry state. The observed features are accounted for by a different pattern of spontaneous symmetry breaking, characterised by condensation of fluctuations and long-range correlations of the order parameter.
format Preprint
id arxiv_https___arxiv_org_abs_2505_24228
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Bose-Einstein Condensation, Fluctuations and Spontaneous Symmetry Breaking
Crisanti, A.
Sarracino, A.
Zannetti, M.
Statistical Mechanics
Quantum Gases
The realisation of Bose-Einstein condensation under grand-canonical conditions has provided the experimental evidence for the simultaneous occurrence of macroscopic fluctuations and phase coherence of the condensate. The observation of these two features, against a consolidated tradition which wants the fluctuations to be pathological (grand-canonical catastrophe) and incompatible with spontaneous symmetry braking, calls for a comprehensive rethinking of the approach to the problem. In this paper we consider the uniform ideal gas in a box and we present an alternative conceptual framework. We show that the usually-employed Bogoliubov quasi-average construction fails to reproduce the broken-symmetry state. The observed features are accounted for by a different pattern of spontaneous symmetry breaking, characterised by condensation of fluctuations and long-range correlations of the order parameter.
title Bose-Einstein Condensation, Fluctuations and Spontaneous Symmetry Breaking
topic Statistical Mechanics
Quantum Gases
url https://arxiv.org/abs/2505.24228