Corner Charge Fluctuation as an Observable for Quantum Geometry and Entanglement in Two-dimensional Insulators

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Hauptverfasser: Tam, Pok Man, Herzog-Arbeitman, Jonah, Yu, Jiabin
Format: Preprint
Veröffentlicht: 2024
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author Tam, Pok Man
Herzog-Arbeitman, Jonah
Yu, Jiabin
author_facet Tam, Pok Man
Herzog-Arbeitman, Jonah
Yu, Jiabin
contents Measuring bipartite fluctuations of a conserved charge, such as the particle number, is a powerful approach to understanding quantum systems. When the measured region has sharp corners, the bipartite fluctuation receives an additional contribution known to exhibit a universal angle-dependence in 2D isotropic and uniform systems. Here we establish that, for generic lattice systems of interacting particles, the corner charge fluctuation is directly related to quantum geometry. We first provide a practical scheme to isolate the corner contribution on lattices, and analytically prove that its angle-dependence in the small-angle limit measures exclusively the integrated quantum metric. A model of a compact obstructed atomic insulator is introduced to illustrate this effect analytically, while numerical verification for various Chern insulator models further demonstrate the experimental relevance of the corner charge fluctuation in a finite-size quantum simulator as a probe of quantum geometry. Last but not least, for free fermions, we unveil an intimate connection between quantum geometry and quantum information through the lens of corner entanglement entropies.
format Preprint
id arxiv_https___arxiv_org_abs_2406_17023
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Corner Charge Fluctuation as an Observable for Quantum Geometry and Entanglement in Two-dimensional Insulators
Tam, Pok Man
Herzog-Arbeitman, Jonah
Yu, Jiabin
Mesoscale and Nanoscale Physics
Quantum Gases
Statistical Mechanics
High Energy Physics - Theory
Quantum Physics
Measuring bipartite fluctuations of a conserved charge, such as the particle number, is a powerful approach to understanding quantum systems. When the measured region has sharp corners, the bipartite fluctuation receives an additional contribution known to exhibit a universal angle-dependence in 2D isotropic and uniform systems. Here we establish that, for generic lattice systems of interacting particles, the corner charge fluctuation is directly related to quantum geometry. We first provide a practical scheme to isolate the corner contribution on lattices, and analytically prove that its angle-dependence in the small-angle limit measures exclusively the integrated quantum metric. A model of a compact obstructed atomic insulator is introduced to illustrate this effect analytically, while numerical verification for various Chern insulator models further demonstrate the experimental relevance of the corner charge fluctuation in a finite-size quantum simulator as a probe of quantum geometry. Last but not least, for free fermions, we unveil an intimate connection between quantum geometry and quantum information through the lens of corner entanglement entropies.
title Corner Charge Fluctuation as an Observable for Quantum Geometry and Entanglement in Two-dimensional Insulators
topic Mesoscale and Nanoscale Physics
Quantum Gases
Statistical Mechanics
High Energy Physics - Theory
Quantum Physics
url https://arxiv.org/abs/2406.17023