Thermodynamical aspects of fermions in external electromagnetic fields

Fuente: arXiv
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Hauptverfasser: Brunetti, Romeo, Fredenhagen, Klaus, Pinamonti, Nicola
Format: Preprint
Veröffentlicht: 2025
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author Brunetti, Romeo
Fredenhagen, Klaus
Pinamonti, Nicola
author_facet Brunetti, Romeo
Fredenhagen, Klaus
Pinamonti, Nicola
contents The thermodynamics of Dirac fields under the influence of external electromagnetic fields is studied. For perturbations which act only for finite time, the influence of the perturbation can be described by an automorphism which can be unitarily implemented in the GNS representations of KMS states, a result long known for the Fock representation. For time-independent perturbations, however, the time evolution cannot be implemented in typical cases, so the standard methods of quantum statistical mechanics do not apply. Instead we show that a smooth switching on of the external potential allows a comparison of the free and the perturbed time evolution, and approach to equilibrium, a possible existence of non-equilibrium stationary states (NESS) and Araki's relative entropy can be investigated. As a byproduct, we find an explicit formula for the relative entropy of gauge invariant quasi-free states.
format Preprint
id arxiv_https___arxiv_org_abs_2505_22413
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Thermodynamical aspects of fermions in external electromagnetic fields
Brunetti, Romeo
Fredenhagen, Klaus
Pinamonti, Nicola
Mathematical Physics
High Energy Physics - Theory
The thermodynamics of Dirac fields under the influence of external electromagnetic fields is studied. For perturbations which act only for finite time, the influence of the perturbation can be described by an automorphism which can be unitarily implemented in the GNS representations of KMS states, a result long known for the Fock representation. For time-independent perturbations, however, the time evolution cannot be implemented in typical cases, so the standard methods of quantum statistical mechanics do not apply. Instead we show that a smooth switching on of the external potential allows a comparison of the free and the perturbed time evolution, and approach to equilibrium, a possible existence of non-equilibrium stationary states (NESS) and Araki's relative entropy can be investigated. As a byproduct, we find an explicit formula for the relative entropy of gauge invariant quasi-free states.
title Thermodynamical aspects of fermions in external electromagnetic fields
topic Mathematical Physics
High Energy Physics - Theory
url https://arxiv.org/abs/2505.22413