Quantum weight: A fundamental property of quantum many-body systems

We introduce the concept of quantum weight as a ground-state property of quantum many-body systems that is encoded in the static structure factor and characterizes density fluctuation at long wavelengths. The quantum weight carries a wealth of information about dielectric responses and optical prope...

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Main Authors: Yugo Onishi, Liang Fu
Format: Article
Language:English
Published: American Physical Society 2025-05-01
Series:Physical Review Research
Online Access:http://doi.org/10.1103/PhysRevResearch.7.023158
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author Yugo Onishi
Liang Fu
author_facet Yugo Onishi
Liang Fu
author_sort Yugo Onishi
collection DOAJ
description We introduce the concept of quantum weight as a ground-state property of quantum many-body systems that is encoded in the static structure factor and characterizes density fluctuation at long wavelengths. The quantum weight carries a wealth of information about dielectric responses and optical properties of the system and is closely related to its quantum geometry. For systems with short-range interactions or low-dimensional Coulomb systems, we show that the many-body quantum metric (which measures the change of the ground state under twisted boundary conditions) can be determined directly from the quantum weight. Notably, the quantum weight is a property of a single ground state and independent of boundary conditions in the thermodynamic limit. Our finding thus enables direct experimental measurement and numerical calculation of the many-body quantum metric. On the other hand, for three-dimensional Coulomb systems, we show that the quantum weight is distinct from the many-body quantum metric due to dielectric screening in three dimensions. We further use dielectric sum rules to derive upper and lower bounds on the quantum weight of real materials in terms of their electron density, static dielectric constant, and plasmon energy. Our work highlights quantum weight as a fundamental material parameter, which can be experimentally determined by x-ray scattering or electron-loss spectroscopy.
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spelling doaj-art-e96c8f62fc9b4754af5a83b8f1be90402025-08-20T02:26:28ZengAmerican Physical SocietyPhysical Review Research2643-15642025-05-017202315810.1103/PhysRevResearch.7.023158Quantum weight: A fundamental property of quantum many-body systemsYugo OnishiLiang FuWe introduce the concept of quantum weight as a ground-state property of quantum many-body systems that is encoded in the static structure factor and characterizes density fluctuation at long wavelengths. The quantum weight carries a wealth of information about dielectric responses and optical properties of the system and is closely related to its quantum geometry. For systems with short-range interactions or low-dimensional Coulomb systems, we show that the many-body quantum metric (which measures the change of the ground state under twisted boundary conditions) can be determined directly from the quantum weight. Notably, the quantum weight is a property of a single ground state and independent of boundary conditions in the thermodynamic limit. Our finding thus enables direct experimental measurement and numerical calculation of the many-body quantum metric. On the other hand, for three-dimensional Coulomb systems, we show that the quantum weight is distinct from the many-body quantum metric due to dielectric screening in three dimensions. We further use dielectric sum rules to derive upper and lower bounds on the quantum weight of real materials in terms of their electron density, static dielectric constant, and plasmon energy. Our work highlights quantum weight as a fundamental material parameter, which can be experimentally determined by x-ray scattering or electron-loss spectroscopy.http://doi.org/10.1103/PhysRevResearch.7.023158
spellingShingle Yugo Onishi
Liang Fu
Quantum weight: A fundamental property of quantum many-body systems
Physical Review Research
title Quantum weight: A fundamental property of quantum many-body systems
title_full Quantum weight: A fundamental property of quantum many-body systems
title_fullStr Quantum weight: A fundamental property of quantum many-body systems
title_full_unstemmed Quantum weight: A fundamental property of quantum many-body systems
title_short Quantum weight: A fundamental property of quantum many-body systems
title_sort quantum weight a fundamental property of quantum many body systems
url http://doi.org/10.1103/PhysRevResearch.7.023158
work_keys_str_mv AT yugoonishi quantumweightafundamentalpropertyofquantummanybodysystems
AT liangfu quantumweightafundamentalpropertyofquantummanybodysystems