How do late-time photons "record" primordial curvature perturbations?
Abstract
Inflationary cosmology faces a fundamental gap between primordial quantum fluctuations and the classical cosmic history inferred from observations. Although the primordial quantum state is a superposition of field configurations, standard cosmology assumes one definite realization of curvature perturbations and uses classical perturbation theory to describe the resulting gravitational potentials, CMB anisotropies, and large-scale structure. Squeezing and decoherence of primordial fluctuations alone do not explain why this one-realization description is physically meaningful. We address this issue through Cosmological Classical Branches (CCBs), using the quantum-information-theoretic notion of physical records. In CCBs, distinct late-time matter components carry compatible records of the same primordial configuration. A record in one component makes that configuration readable, while a disjoint compatible record suppresses interference accessible to operations on the first. Each branch thus admits a common c-number primordial label at finite resolution, while the global quantum superposition persists. This Letter summarizes the framework developed in Ref.~\cite{Kuroda2026CCB}.
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BibTeX
@misc{kuroda2026latetime,
title = {{How do late-time photons "record" primordial curvature perturbations?}},
author = {Tomotaka Kuroda and Fumiya Sano and Yusuke Yamada},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.23999},
eprint = {2610.23999},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.23999},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - How do late-time photons "record" primordial curvature perturbations?
AU - Tomotaka Kuroda
AU - Fumiya Sano
AU - Yusuke Yamada
PY - 2026
DA - 2026/10/15
PB - arXiv
DO - 10.48550/arxiv.2610.23999
UR - https://arxiv.org/abs/2610.23999
AB - Inflationary cosmology faces a fundamental gap between primordial quantum fluctuations and the classical cosmic history inferred from observations. Although the primordial quantum state is a superposition of field configurations, standard cosmology assumes one definite realization of curvature perturbations and uses classical perturbation theory to describe the resulting gravitational potentials, CMB anisotropies, and large-scale structure. Squeezing and decoherence of primordial fluctuations alone do not explain why this one-realization description is physically meaningful. We address this issue through Cosmological Classical Branches (CCBs), using the quantum-information-theoretic notion of physical records. In CCBs, distinct late-time matter components carry compatible records of the same primordial configuration. A record in one component makes that configuration readable, while a disjoint compatible record suppresses interference accessible to operations on the first. Each branch thus admits a common c-number primordial label at finite resolution, while the global quantum superposition persists. This Letter summarizes the framework developed in Ref.~\cite{Kuroda2026CCB}.
ER -