Description This work proposes an information-theoretic framework for describing the quantum–classical transition during cosmological inflation through open quantum system dynamics and entanglement evolution. The study introduces a normalized Quantum Persistence Function (QPF) as a scale-invariant diagnostic measure of residual quantum coherence, formulated in representation-independent form using reduced density matrix purity and entropy growth. The framework connects microscopic decoherence processes with macroscopic cosmological observables by applying spin–boson open-system dynamics to inflationary perturbations. Classical emergence is interpreted as a dynamical suppression of quantum coherence driven by entanglement entropy growth between cosmological modes rather than by simple interference cancellation. Observational constraints from primordial Gaussianity bounds are used to derive an efficiency condition for decoherence during reheating, expressed as a lower bound on the decoherence functional. The results show that classicalization occurs well below holographic entropy saturation limits, suggesting that cosmological classical emergence is governed primarily by dynamical information redistribution rather than fundamental information capacity thresholds. This work is deposited on Zenodo as an open scientific preprint to encourage constructive discussion and feedback from the scientific community. KEYWORDS: Quantum classical transition; decoherence theory; inflationary cosmology; open quantum systems; entanglement entropy; cosmological perturbations; quantum persistence function; information theory in physics; primordial fluctuations; classical emergence dynamics
Description This work proposes an information-theoretic framework for describing the quantum–classical transition during cosmological inflation through open quantum system dynamics and entanglement evolution. The study introduces a normalized Quantum Persistence Function (QPF) as a scale-invariant diagnostic measure of residual quantum coherence, formulated in representation-independent form using reduced density matrix purity and entropy growth. The framework connects microscopic decoherence processes with macroscopic cosmological observables by applying spin–boson open-system dynamics to inflationary perturbations. Classical emergence is interpreted as a dynamical suppression of quantum coherence driven by entanglement entropy growth between cosmological modes rather than by simple interference cancellation. Observational constraints from primordial Gaussianity bounds are used to derive an efficiency condition for decoherence during reheating, expressed as a lower bound on the decoherence functional. The results show that classicalization occurs well below holographic entropy saturation limits, suggesting that cosmological classical emergence is governed primarily by dynamical information redistribution rather than fundamental information capacity thresholds. This work is deposited on Zenodo as an open scientific preprint to encourage constructive discussion and feedback from the scientific community. KEYWORDS: Quantum classical transition; decoherence theory; inflationary cosmology; open quantum systems; entanglement entropy; cosmological perturbations; quantum persistence function; information theory in physics; primordial fluctuations; classical emergence dynamics
Description: This work presents a quantitative framework for describing the quantum–classical transition as a continuous dynamical process governed by open quantum system interactions. A normalized Quantum Persistence Function is introduced to measure residual quantum coherence, allowing classical emergence to be characterized through a scale-dependent suppression criterion. The model is constructed using a microscopic spin–boson open-system foundation and extends decoherence analysis to inflationary cosmology. The framework connects dynamical decoherence bounds with observational constraints derived from primordial statistics measured by the Planck Collaboration. The formulation builds conceptually on decoherence theory associated with Wojciech H. Zurek and provides a diagnostic criterion for residual coherence survival across cosmological scales. The results aim to provide a practical quantitative tool for evaluating classicalization efficiency in inflationary models and for relating open-system quantum dynamics to empirical cosmological observations. KEYWORDS: Quantum–classical transition; decoherence theory; open quantum systems; inflationary cosmology; residual quantum coherence; spin–boson model; classicalization dynamics; primordial perturbations; cosmological quantum mechanics
Description : This work introduces a novel, model-independent diagnostic framework for quantifying quantum decoherence in primordial inflationary perturbations. The study addresses the fundamental problem of the quantum-to-classical transition in cosmology by defining a normalized persistence functional that captures the suppression of quantum coherence over time. Within an open quantum system approach, each perturbation mode is treated as an effective quantum degree of freedom interacting with an environment, leading to Gaussian suppression of off-diagonal density matrix elements. The proposed functional provides a direct and scalable measure of decoherence efficiency without relying on detailed microscopic modeling. A key feature of the framework is the introduction of a residual coherence parameter, which accounts for possible late-time deviations from complete classicalization. The work further establishes a monotonicity property for the decoherence functional and connects the persistence measure to entropy growth, offering an information-theoretic interpretation of the decoherence process. Importantly, the framework suggests a phenomenological link between residual coherence and observable non-Gaussianity in the cosmic microwave background, opening a pathway for potential observational constraints. The proposed diagnostic functional is broadly applicable across inflationary models and provides a unified tool for comparing decoherence efficiency under different environmental interactions. This work lays the foundation for future studies on quantum signatures in cosmological observables and the persistence of quantum features in the early universe. Keywords : Quantum Decoherence Inflationary Cosmology Primordial Perturbations Open Quantum Systems Quantum-to-Classical Transition Non-Gaussianity Cosmological Perturbation Theory Density Matrix Quantum Cosmology Early Universe Physics Decoherence Functional Entropy and Information Theory
This research introduces a novel quantitative framework for understanding one of the most fundamental questions in theoretical physics: How and when do quantum systems become classical? By developing a normalized Quantum Persistence Function (QPF) , we provide a continuous measure of residual quantum coherence in open systems interacting with their environment. The framework is rigorously derived from the spin-boson model—a paradigm for studying decoherence—and distinguishes between Markovian (memoryless) and non-Markovian environments based on spectral density structure (Keywords) Quantum decoherence Inflationary cosmology Open quantum systems Quantum–classical transition Primordial perturbations Cosmic Microwave Background Non-Gaussianity Spin-boson model Environmental entanglement Planck mission
This preprint develops a model-independent diagnostic framework for evaluating decoherence efficiency in inflationary curvature perturbations within an open quantum system formulation. The work does not introduce a new decoherence mechanism; instead, it constructs a normalized dimensionless functional intended to provide a systematic basis for comparing environmental decoherence scenarios in primordial cosmology. A persistence functional is derived to characterize the attenuation of off-diagonal density matrix components under inflationary expansion. Using a representative toy open-system model, the analysis demonstrates that the functional exhibits rapid suppression behavior associated with the exponential growth of comoving volume during inflation. The framework further suggests that residual quantum coherence may contribute to higher-order correlation functions of curvature perturbations. Accordingly, observational constraints on primordial non-Gaussianity may be interpreted as indirect lower bounds on decoherence efficiency. The formulation is intended as a diagnostic tool rather than a proposal of a new physical decoherence process. Keywords : Inflationary Cosmology Quantum Decoherence Primordial Perturbations Open Quantum Systems Classicality Non-Gaussianity
In this work, we systematically investigate the quantum-information diagnostics of cosmological perturbations with a nontrivial sound speed, utilizing a normalized open two-mode squeezed-state framework. Rather than introducing new observables, our analysis focuses on how a modified sound speed dynamically reshapes the Schrödinger evolution of the squeezing parameters (rk and φk). We demonstrate how these dynamical changes are inherited by the reduced density matrix of the observable sector. By employing a sound-speed-resonance parametrization, we derive and evaluate the purity, von Neumann entropy, Rényi entropies, and logarithmic negativity. To overcome the intrinsic multiscale stiffness of the post-inflationary equations, we introduce a bounded variable x=tanhrk as a partial regularization, which enables reliable numerical simulations exclusively within the inflationary regime. Our numerical results reveal that a nontrivial sound speed significantly suppresses the purity of the reduced state, indicating enhanced effective mixedness. Simultaneously, it strongly amplifies and modulates both the entropic and entanglement diagnostics. More precisely, a nontrivial sound speed postpones the onset of classicality by modulating the decoherence process. Ultimately, we show that a nontrivial sound speed leaves distinct and identifiable quantum-information signatures within the entanglement structure of the early universe.
Redundancy-Limited Emergence of Classical Histories in Quantum Systems This work investigates how classical reality emerges from underlying quantum dynamics, focusing on the role of environmental information, noise, and fundamental entropy limits. In quantum theory, systems evolve into superpositions of many possible outcomes. However, in practice we observe a world with definite, classical histories. A widely accepted explanation is decoherence, in which interactions with the environment suppress interference between different quantum states. More recent developments, particularly in quantum Darwinism, emphasize that classical information becomes objective when it is redundantly recorded across many independent parts of the environment. This paper addresses a key unresolved question: how many distinct classical histories can physically exist? To answer this, we construct a minimal computational model in which a system’s history is encoded into multiple environmental fragments, each subject to noise. By computing how much information about the system can be recovered from subsets of these fragments, we identify a characteristic scale that determines how many fragments are required to reconstruct the system’s history. Our results reveal a simple and robust relationship: the ability to recover classical information depends on the entropy of the noise affecting environmental records. As noise increases, more fragments are required to reconstruct a history, reflecting a loss of distinguishability. This leads to the definition of a “recoverability factor,” which quantifies how efficiently entropy can be converted into usable, classical information. We then connect this information-theoretic result to fundamental bounds from gravitational physics. In particular, existing entropy bounds limit the total amount of information that can pass through a region of spacetime. We show that only a fraction of this entropy—determined by the recoverability factor—can contribute to distinguishable classical histories. This leads to a new principle: the number of classical histories is not limited only by total entropy, but by the efficiency with which that entropy can be encoded, preserved, and accessed. Applying this framework to cosmological entropy estimates, we derive explicit upper bounds on the number of distinguishable classical histories in the observable universe. While this number is extraordinarily large, it is nonetheless finite and strongly constrained by both entropy and noise. These results refine the standard picture of quantum branching. While quantum theory allows a vast number of possible outcomes, only a subset can become physically meaningful in the sense of being stable, redundantly recorded, and accessible to observers. More broadly, this work provides a quantitative bridge between decoherence theory, information theory, and gravitational entropy bounds. It suggests that classical reality is fundamentally constrained not just by physical laws governing entropy, but by the efficiency of information transfer within those constraints.