Van Hove singularities in stabilizer entropy densities

Fuente: arXiv
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Main Authors: Iannotti, Daniele, Venuti, Lorenzo Campos, Hamma, Alioscia
Format: Preprint
Published: 2025
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author Iannotti, Daniele
Venuti, Lorenzo Campos
Hamma, Alioscia
author_facet Iannotti, Daniele
Venuti, Lorenzo Campos
Hamma, Alioscia
contents The probability distribution of a measure of non-stabilizerness, also known as magic, is investigated for Haar-random pure quantum states. Focusing on the stabilizer Rényi entropies, the associated probability density functions (PDFs) are found to display distinct non-analytic features analogous to Van Hove singularities in condensed matter systems. For a single qubit, the stabilizer purity exhibits a logarithmic divergence at a critical value corresponding to a saddle point on the Bloch sphere. This divergence occurs at the $|H\rangle$-magic states, which hence can be identified as states for which the density of non-stabilizerness in the Hilbert space is infinite. An exact expression for the PDF is derived for the case $α= 2$, with analytical predictions confirmed by numerical simulations. The logarithmic divergence disappears for dimensions $d \ge 3$, in agreement with the behavior of ordinary Van Hove singularities on flat manifolds. In addition, it is shown that, for one qubit, the linear stabilizer entropy is directly related to the partial incompatibility of quantum measurements, one of the defining properties of quantum mechanics, at the basis of Stern-Gerlach experiments.
format Preprint
id arxiv_https___arxiv_org_abs_2510_22253
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Van Hove singularities in stabilizer entropy densities
Iannotti, Daniele
Venuti, Lorenzo Campos
Hamma, Alioscia
Quantum Physics
Mathematical Physics
The probability distribution of a measure of non-stabilizerness, also known as magic, is investigated for Haar-random pure quantum states. Focusing on the stabilizer Rényi entropies, the associated probability density functions (PDFs) are found to display distinct non-analytic features analogous to Van Hove singularities in condensed matter systems. For a single qubit, the stabilizer purity exhibits a logarithmic divergence at a critical value corresponding to a saddle point on the Bloch sphere. This divergence occurs at the $|H\rangle$-magic states, which hence can be identified as states for which the density of non-stabilizerness in the Hilbert space is infinite. An exact expression for the PDF is derived for the case $α= 2$, with analytical predictions confirmed by numerical simulations. The logarithmic divergence disappears for dimensions $d \ge 3$, in agreement with the behavior of ordinary Van Hove singularities on flat manifolds. In addition, it is shown that, for one qubit, the linear stabilizer entropy is directly related to the partial incompatibility of quantum measurements, one of the defining properties of quantum mechanics, at the basis of Stern-Gerlach experiments.
title Van Hove singularities in stabilizer entropy densities
topic Quantum Physics
Mathematical Physics
url https://arxiv.org/abs/2510.22253