dorsal/arxiv
View SchemaEntanglement as an Observer-Dependent Concept: An Application to Quantum Phase Transitions
| Authors | Gerardo Ortiz, Rolando Somma, Howard Barnum, Emanuel Knill, Lorenza Viola |
|---|---|
| Categories | |
| ArXiv ID | quant-ph/0403043 |
| URL | https://arxiv.org/abs/quant-ph/0403043 |
Abstract
This paper addresses the following main question: Do we have a theoretical understanding of entanglement applicable to a full variety of physical settings? It is clear that not only the assumption of distinguishability, but also the few-subsystem scenario, are too narrow to embrace all possible physical settings. In particular, the need to go beyond the traditional subsystem-based framework becomes manifest when one tries to apply the conventional concept of entanglement to the physics of matter, since the constituents of a quantum many-body system are indistinguishable particles. We shall discuss here a notion of generalized entanglement, which can be applied to any operator language (fermions, bosons, spins, etc.) used to describe a physical system and which includes the conventional entanglement settings introduced to date in a unified fashion. This is realized by noticing that entanglement is an observer-dependent concept, whose properties are determined by the expectations of a distinguished set of observables without reference to a preferred subsystem decomposition, i.e., it depends on the physically relevant point of view. This viewpoint depends in turn upon the relationship between different sets of observables that determine our ability to control the system of interest. Indeed, the extent to which entanglement is present depends on the observables used to measure a system and describe its states. This represents a most conspicuous advantage as will be highlighted by the condensed-matter application we will discuss.
{
"annotation_id": "3df1e470-9705-4cc0-822b-f6f83cc9d1b1",
"date_created": "2026-03-02T18:02:07.095000Z",
"date_modified": "2026-03-02T18:02:07.095000Z",
"file_hash": "ad39a3806e19ca737b0cd5d2f5735425c4cc3c96eddad0b593ee363e23497b34",
"private": false,
"record": {
"abstract": "This paper addresses the following main question: Do we have a theoretical\nunderstanding of entanglement applicable to a full variety of physical\nsettings? It is clear that not only the assumption of distinguishability, but\nalso the few-subsystem scenario, are too narrow to embrace all possible\nphysical settings. In particular, the need to go beyond the traditional\nsubsystem-based framework becomes manifest when one tries to apply the\nconventional concept of entanglement to the physics of matter, since the\nconstituents of a quantum many-body system are indistinguishable particles. We\nshall discuss here a notion of generalized entanglement, which can be applied\nto any operator language (fermions, bosons, spins, etc.) used to describe a\nphysical system and which includes the conventional entanglement settings\nintroduced to date in a unified fashion. This is realized by noticing that\nentanglement is an observer-dependent concept, whose properties are determined\nby the expectations of a distinguished set of observables without reference to\na preferred subsystem decomposition, i.e., it depends on the physically\nrelevant point of view. This viewpoint depends in turn upon the relationship\nbetween different sets of observables that determine our ability to control the\nsystem of interest. Indeed, the extent to which entanglement is present depends\non the observables used to measure a system and describe its states. This\nrepresents a most conspicuous advantage as will be highlighted by the\ncondensed-matter application we will discuss.",
"arxiv_id": "quant-ph/0403043",
"authors": [
"Gerardo Ortiz",
"Rolando Somma",
"Howard Barnum",
"Emanuel Knill",
"Lorenza Viola"
],
"categories": [
"quant-ph",
"cond-mat.str-el"
],
"title": "Entanglement as an Observer-Dependent Concept: An Application to Quantum Phase Transitions",
"url": "https://arxiv.org/abs/quant-ph/0403043"
},
"schema_id": "dorsal/arxiv",
"source": {
"execution_id": "4e638236-c080-4cbf-b2a5-feb7943f0917",
"id": "arXiv Dataset IDs",
"type": "Model",
"variant": "snapshot-2026-03-01",
"version": "0.1.0"
},
"user_id": 1000002
}