Star-exponential for Fermi systems and the Feynman-Kac formula

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Main Authors: Berra-Montiel, J., García-Compeán, H., Kafuri, A., Molgado, A.
Format: Preprint
Published: 2026
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author Berra-Montiel, J.
García-Compeán, H.
Kafuri, A.
Molgado, A.
author_facet Berra-Montiel, J.
García-Compeán, H.
Kafuri, A.
Molgado, A.
contents Inspired by the formalism that relates the star-exponential with the quantum propagator for bosonic systems, in this work we introduce the analogous extension for the fermionic case. In particular, we analyse the problem of calculating the star-exponential (i.e., the symbol of the evolution operator) for Fermi systems within the deformation quantization program. Grassmann variables and coherent states are considered in order to obtain a closed-form expression for the fermionic star-exponential in terms of its associated propagator. As a primary application, a fermionic version of the Feynman-Kac formula is derived within this formalism, thus allowing a straightforward calculation of the ground state energy in phase space. Finally, the method is validated by successfully applying it to the simple harmonic and driven Fermi oscillators, for which the results developed here provide a powerful alternative computational tool for the study of fermionic systems.
format Preprint
id arxiv_https___arxiv_org_abs_2603_03558
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Star-exponential for Fermi systems and the Feynman-Kac formula
Berra-Montiel, J.
García-Compeán, H.
Kafuri, A.
Molgado, A.
Quantum Physics
High Energy Physics - Theory
Mathematical Physics
Inspired by the formalism that relates the star-exponential with the quantum propagator for bosonic systems, in this work we introduce the analogous extension for the fermionic case. In particular, we analyse the problem of calculating the star-exponential (i.e., the symbol of the evolution operator) for Fermi systems within the deformation quantization program. Grassmann variables and coherent states are considered in order to obtain a closed-form expression for the fermionic star-exponential in terms of its associated propagator. As a primary application, a fermionic version of the Feynman-Kac formula is derived within this formalism, thus allowing a straightforward calculation of the ground state energy in phase space. Finally, the method is validated by successfully applying it to the simple harmonic and driven Fermi oscillators, for which the results developed here provide a powerful alternative computational tool for the study of fermionic systems.
title Star-exponential for Fermi systems and the Feynman-Kac formula
topic Quantum Physics
High Energy Physics - Theory
Mathematical Physics
url https://arxiv.org/abs/2603.03558