Equilibration and the Eigenstate Thermalization Hypothesis as Limits to Observing Macroscopic Quantum Superpositions

Fuente: arXiv
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Autori principali: Carvalho, Gabriel Dias, Correia, Pedro S., de Oliveira, Thiago R.
Natura: Preprint
Pubblicazione: 2025
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author Carvalho, Gabriel Dias
Correia, Pedro S.
de Oliveira, Thiago R.
author_facet Carvalho, Gabriel Dias
Correia, Pedro S.
de Oliveira, Thiago R.
contents Macroscopic quantum superpositions are widely believed to be unobservable because large systems cannot be perfectly isolated from their environments. Here, we show that even under perfect isolation, intrinsic unitary dynamics with the eigenstate thermalization hypothesis suppress the observable signatures of macroscopic coherence. Using the GHZ state as a representative example, we demonstrate that while fully correlated measurements can initially distinguish a macroscopic superposition from its corresponding classical mixture, generic many-body evolution renders them operationally indistinguishable for most times during the evolution. By analyzing both distinguishability measures and established quantifiers of macroscopic quantumness, we find that equilibration not only hides coherence from accessible observables but also suppresses macroscopic superpositions themselves. These results identify unitary thermalization, independent of environmental decoherence, as a fundamental mechanism that limits the emergence of macroscopic quantum effects.
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id arxiv_https___arxiv_org_abs_2512_11522
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publishDate 2025
record_format arxiv
spellingShingle Equilibration and the Eigenstate Thermalization Hypothesis as Limits to Observing Macroscopic Quantum Superpositions
Carvalho, Gabriel Dias
Correia, Pedro S.
de Oliveira, Thiago R.
Quantum Physics
Macroscopic quantum superpositions are widely believed to be unobservable because large systems cannot be perfectly isolated from their environments. Here, we show that even under perfect isolation, intrinsic unitary dynamics with the eigenstate thermalization hypothesis suppress the observable signatures of macroscopic coherence. Using the GHZ state as a representative example, we demonstrate that while fully correlated measurements can initially distinguish a macroscopic superposition from its corresponding classical mixture, generic many-body evolution renders them operationally indistinguishable for most times during the evolution. By analyzing both distinguishability measures and established quantifiers of macroscopic quantumness, we find that equilibration not only hides coherence from accessible observables but also suppresses macroscopic superpositions themselves. These results identify unitary thermalization, independent of environmental decoherence, as a fundamental mechanism that limits the emergence of macroscopic quantum effects.
title Equilibration and the Eigenstate Thermalization Hypothesis as Limits to Observing Macroscopic Quantum Superpositions
topic Quantum Physics
url https://arxiv.org/abs/2512.11522