An asymmetry lower bound on fermionic non-Gaussianity

Fuente: arXiv
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Hauptverfasser: Ares, Filiberto, Mazzoni, Michele, Murciano, Sara, Szász-Schagrin, Dávid, Calabrese, Pasquale, Piroli, Lorenzo
Format: Preprint
Veröffentlicht: 2026
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author Ares, Filiberto
Mazzoni, Michele
Murciano, Sara
Szász-Schagrin, Dávid
Calabrese, Pasquale
Piroli, Lorenzo
author_facet Ares, Filiberto
Mazzoni, Michele
Murciano, Sara
Szász-Schagrin, Dávid
Calabrese, Pasquale
Piroli, Lorenzo
contents Fermionic Gaussian states are a fundamental tool in many-body physics, faithfully representing non-interacting quantum systems and allowing for efficient numerical simulations. Given a many-body wave function, it is therefore interesting to ask how much it differs from that of a Gaussian state, as quantified by the notion of non-Gaussianity. In this work, we relate measures of non-Gaussianity with the Shannon entropy of the particle-number distribution, coinciding with the particle-number asymmetry for pure states. We derive a lower bound on the relative entropy of non-Gaussianity in terms of the exponential of the Shannon entropy, and study numerically its tightness for large system sizes. Our bound is non-trivial for large values of the asymmetry and relies on the concentration of the particle-number distribution of (mixed) fermionic Gaussian states. Since the Shannon entropy of the particle-number distribution is often efficient to compute or experimentally measure, our results can be viewed as a practical way to lower bound non-Gaussianity, highlighting a non-trivial interplay with particle-number asymmetry.
format Preprint
id arxiv_https___arxiv_org_abs_2603_16762
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle An asymmetry lower bound on fermionic non-Gaussianity
Ares, Filiberto
Mazzoni, Michele
Murciano, Sara
Szász-Schagrin, Dávid
Calabrese, Pasquale
Piroli, Lorenzo
Quantum Physics
Statistical Mechanics
Mathematical Physics
Fermionic Gaussian states are a fundamental tool in many-body physics, faithfully representing non-interacting quantum systems and allowing for efficient numerical simulations. Given a many-body wave function, it is therefore interesting to ask how much it differs from that of a Gaussian state, as quantified by the notion of non-Gaussianity. In this work, we relate measures of non-Gaussianity with the Shannon entropy of the particle-number distribution, coinciding with the particle-number asymmetry for pure states. We derive a lower bound on the relative entropy of non-Gaussianity in terms of the exponential of the Shannon entropy, and study numerically its tightness for large system sizes. Our bound is non-trivial for large values of the asymmetry and relies on the concentration of the particle-number distribution of (mixed) fermionic Gaussian states. Since the Shannon entropy of the particle-number distribution is often efficient to compute or experimentally measure, our results can be viewed as a practical way to lower bound non-Gaussianity, highlighting a non-trivial interplay with particle-number asymmetry.
title An asymmetry lower bound on fermionic non-Gaussianity
topic Quantum Physics
Statistical Mechanics
Mathematical Physics
url https://arxiv.org/abs/2603.16762