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arXiv · 1007.3877

Equivalence condition for the canonical and microcanonical ensembles in coupled spin systems

Wenxian Zhang·C. P. Sun·Franco Nori
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Abstract

It is typically assumed, without justification, that a weak coupling between a system and a bath is a necessary condition for the equivalence of a canonical ensemble and a microcanonical ensemble. For instance, in a canonical ensemble, temperature emerges if the system and the bath are uncoupled or weakly coupled. We investigate the validity region of this weak coupling approximation, using a coupled composite-spin system. Our results show that the spin coupling strength can be as large as the level spacing of the system, indicating that the weak coupling approximation has a much wider region of validity than usually expected.

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Wenxian Zhang, C. P. Sun, Franco Nori. 2010-07-22. Equivalence condition for the canonical and microcanonical ensembles in coupled spin systems. https://doi.org/10.1103/physreve.82.041127

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