Spatial Leggett-Garg Inequalities

Fuente: arXiv
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Main Authors: Müller-Rigat, Guillem, Farina, Donato, Lewenstein, Maciej, Tononi, Andrea
Format: Preprint
Published: 2025
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author Müller-Rigat, Guillem
Farina, Donato
Lewenstein, Maciej
Tononi, Andrea
author_facet Müller-Rigat, Guillem
Farina, Donato
Lewenstein, Maciej
Tononi, Andrea
contents We formulate a spatial extension of the Leggett-Garg inequality by considering three distant observers locally measuring a many-body system at three subsequent times. The spatial form, in particular, is specially suited to analyze propagation of quantum perturbations through spin chains, by capturing how a measurement at one site can later affect distant sites due to the interactions. We illustrate our proposal for a Heisenberg chain in a magnetic field, showing indeed that the first inequality-violation time scales proportionally to the distance between measuring parties. We attribute this phenomenon to Lieb-Robinson physics and, confirming this connection, we find that violations are anticipated when increasing the interaction range. The inequality violation, readily observable in current experiments, demonstrates the incompatibility between two-point correlation functions and the macrorealistic hypothesis. In outlook, spatial Leggett-Garg inequalities constitute a new tool for analyzing the non-relativistic dynamics of many-body quantum systems.
format Preprint
id arxiv_https___arxiv_org_abs_2507_03440
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Spatial Leggett-Garg Inequalities
Müller-Rigat, Guillem
Farina, Donato
Lewenstein, Maciej
Tononi, Andrea
Quantum Physics
Quantum Gases
We formulate a spatial extension of the Leggett-Garg inequality by considering three distant observers locally measuring a many-body system at three subsequent times. The spatial form, in particular, is specially suited to analyze propagation of quantum perturbations through spin chains, by capturing how a measurement at one site can later affect distant sites due to the interactions. We illustrate our proposal for a Heisenberg chain in a magnetic field, showing indeed that the first inequality-violation time scales proportionally to the distance between measuring parties. We attribute this phenomenon to Lieb-Robinson physics and, confirming this connection, we find that violations are anticipated when increasing the interaction range. The inequality violation, readily observable in current experiments, demonstrates the incompatibility between two-point correlation functions and the macrorealistic hypothesis. In outlook, spatial Leggett-Garg inequalities constitute a new tool for analyzing the non-relativistic dynamics of many-body quantum systems.
title Spatial Leggett-Garg Inequalities
topic Quantum Physics
Quantum Gases
url https://arxiv.org/abs/2507.03440