This work presents a significant advance in our understanding of macroscopic quantum phenomena and their potential for technological application. By providing a quantitatively-grounded theoretical framework—Coherence–Selection Interface Theory (CSIT)—we demonstrate that a class of long-observed but unexplained anomalous phenomena can be understood as engineered quantum coherence. The primary advance is twofold: first, we provide a falsifiable, thermodynamically consistent model for non-inertial propulsion and energy harvesting from environmental noise, directly explaining the observed correlation between Unidentified Anomalous Phenomena (UAPs) and nuclear facilities. Second, we establish the high probability of this model through a rigorous Bayesian analysis, yielding a posterior probability P(CSIT|data) > 0.99. This research reframes the UAP discussion from a speculative inquiry into a concrete problem of quantum engineering, opening a new avenue for research at the intersection of quantum information, thermodynamics, and observational physics, with profound implications for propulsion and energy systems. Keywords: quantum coherence, NISQ systems, non-unitary history, macroscopic phenomena, UAP explanation
This work presents a significant advance in our understanding of macroscopic quantum phenomena and their potential for technological application. By providing a quantitatively-grounded theoretical framework—Coherence–Selection Interface Theory (CSIT)—we demonstrate that a class of long-observed but unexplained anomalous phenomena can be understood as engineered quantum coherence. The primary advance is twofold: first, we provide a falsifiable, thermodynamically consistent model for non-inertial propulsion and energy harvesting from environmental noise, directly explaining the observed correlation between Unidentified Anomalous Phenomena (UAPs) and nuclear facilities. Second, we establish the high probability of this model through a rigorous Bayesian analysis, yielding a posterior probability P(CSIT|data) > 0.99. This research reframes the UAP discussion from a speculative inquiry into a concrete problem of quantum engineering, opening a new avenue for research at the intersection of quantum information, thermodynamics, and observational physics, with profound implications for propulsion and energy systems. Keywords: quantum coherence, NISQ systems, non-unitary history, macroscopic phenomena, UAP explanation
Decoherence and thermodynamic irreversibility are widely regarded as sufficient to explain the emergence of classical behavior from quantum mechanics. Decoherence suppresses interference between branches of the wavefunction, while entropy production provides a direction to macroscopic time. However, neither mechanism alone explains why macroscopic physics exhibits a single, persistent, globally consistent classical history rather than fragmentation into mutually incompatible record sets. In this work, we identify and formalize this unresolved issue as the classicality gap. We show that in finite systems subject to nonzero noise and irreversible record formation, decoherence and entropy production are generically insufficient to stabilize a single coherent macroscopic history. Instead, absent a history-level selection mechanism, redundant records diverge and macroscopic identity becomes ill-defined. We present a general instability result demonstrating this fragmentation tendency and introduce history-level constraint restoration as the minimal structural mechanism capable of preventing it. This mechanism operates without new microdynamics, collapse postulates, or observer dependence. We derive qualitative phase boundaries separating stable and unstable regimes and propose concrete experimental protocols on NISQ-era quantum platforms that can falsify the necessity of history selection. Our results establish that persistent classicality is not guaranteed by decoherence alone, but requires selection acting on histories under irreversible constraints. Keywords: classicality emergence, decoherence limits, record inconsistency, history instability, quantum-to-classical transition, irreversibility, entropy production, information persistence, open quantum systems, foundations of physics
The emergence of a stable, classical world from the underlying quantum reality is a central puzzle of modern physics. While decoherence explains the suppression of quantum interference, it does not, by itself, explain the selection of specific, robust classical histories. Here, we present a complete, end-to-end theory for the emergence of classicality, grounded in the thermodynamics of irreversible record-formation and testable on current-generation quantum computers. We first derive a consistent, directed temporal order from thermodynamic principles, resolving known issues with relational time concepts. We then argue that the coherence of histories within this emergent time is unstable to noise unless actively stabilized by a local, error-correcting-like mechanism. We formalize this mechanism as a projection onto a constrained subspace of the history Hilbert space and argue for its stability for a general class of noise models. Finally, we map this mechanism onto the dynamics of a 2D lattice of superconducting qubits, where the constraints are identified with the stabilizers of the surface code. We derive an analytic expression for the phase boundary between stable and unstable regimes, validate it with illustrative calculations based on the analytic theory, and propose a specific experiment on a trapped-ion quantum computer to test a unique, falsifiable power-spectrum signature. This work bridges the gap between foundational theory and experimental reality, providing a concrete, testable mechanism for the emergence of classicality.
Out-of-equilibrium quantum many-body systems stand at the forefront of modern theoretical physics, addressing fundamental questions on thermalization, transport, and universal phenomena. These fields, already well established in condensed matter, statistical physics, quantum optics, and quantum information theory, are progressively gaining even greater relevance with the rapid development of quantum technologies and simulation, which inherently operate in dynamical regimes. In recent years, the traditional paradigm of unitary quantum evolution has been expanded to include measurements, opening new directions in out-of-equilibrium physics. At the core of these advances lie measurement-induced phase transitions (MIPTs), which have emerged as a new class of dynamical critical phenomena characterizing the general behavior of monitored quantum dynamics. When external monitoring intertwines with unitary evolution, many-body quantum correlations change their structure, giving rise to distinct entanglement phases of matter. This discovery has sparked enormous interest in MIPTs, leading to significant advances in open quantum systems, entanglement theory, and more broadly quantum complexity. Despite much progress, a full understanding of monitored many-body dynamics is far from complete, leaving several open questions on the nature of MIPTs, their experimental observability, and the possibilities offered by measurements to enhance control over synthetic quantum matter. These issues persist due to the intrinsic complexity of the problem and the lack of efficient tools to study it, mainly caused by the stochastic character of monitored evolution. This thesis addresses these challenges by expanding the investigation of measurement-induced phenomena in new settings and introducing innovative probes of entanglement and many-body quantum complexity for MIPTs. A core question we investigate is the role of symmetries, non-ergodicity, and especially integrability in measurement-induced criticality, which dramatically affect the non-equilibrium phases. We further explore how these phenomena extend beyond bipartite quantum correlations to multipartite entanglement and quantum non-stabilizerness, highlighting the non-trivial interplay between measurements and complexity notions rooted in quantum information theory. Finally, we focus on the compelling problem of decoherence, modeling how noise spoils entanglement structures. These findings, supported by advanced numerical simulations and theoretical analysis, deepen the current understanding of entanglement, complexity, and integrability in monitored quantum many-body systems, offering new perspectives on their rich behavior. In parallel, we address the experimental problem of dissipation in MIPTs, which is of key relevance for practical implementations. We anticipate the present investigation to foster future research on the nature of monitored dynamical critical phenomena and, more broadly, the applications of measurements in quantum state evolution.
The quantum measurement problem is commonly framed as a tension between unitary microscopic dynamics and the appearance of definite macroscopic outcomes. Decoherence theory explains the suppression of interference but does not explain why a single, persistent outcome is realized rather than a superposition of mutually incompatible macroscopic records. Interpretive responses—including collapse models, many-worlds branching, and observer-centric accounts—add ontological or epistemic structure beyond standard quantum mechanics. In this work, we show that such supplementation is unnecessary. We demonstrate that decoherence alone is generically insufficient to stabilize consistent macroscopic measurement histories under irreversible record formation. We introduce history-level coherence selection as a minimal structural requirement for persistent outcomes. This mechanism operates without modifying unitary dynamics, introducing collapse postulates, or invoking observers. We show that measurement outcomes correspond to stable, selection-supported histories rather than instantaneous state reductions. This reframing resolves the measurement problem by identifying the missing macroscopic mechanism—history selection under irreversible constraint—rather than by altering quantum theory. Keywords: quantum measurement problem, history selection, decoherence insufficiency, classical records, interpretation of quantum mechanics, consistent histories, irreversibility, information flow, foundational physics, measurement theory
The muon anomalous magnetic moment remains one of the most persistent discrepancies between experiment and Standard Model prediction. Existing explanations invoke either hadronic uncertainties or new particle degrees of freedom. Here we propose a third explanatory class: a thermodynamic residual arising from entropy-paid stabilization of a recordable muon spin history in an open quantum environment. We parameterize the excess as where is the irreversible entropy cost required to select and stabilize a persistent measurement branch. Matching the Fermilab excess implies , corresponding to bits of erased superposition under Landauer bookkeeping. This value is consistent, at the order-of-magnitude level, with vacuum mode counting at the electroweak scale. Crucially, this framework predicts a sign-definite dependence of on environmental entropy flux and sharp cross-lepton constraints, providing falsifiable tests that distinguish it from mediator-based explanations. If validated, this result identifies entropy-paid history selection as a previously unrecognized thermodynamic contribution to the foundations of precision quantum measurement. Keywords: Muon anomalous magnetic moment, quantum thermodynamics, open quantum systems, entropy production, precision measurements, quantum measurement theory, Landauer principle, nonequilibrium statistical mechanics, environmental decoherence, large deviation theory.
Quantum entanglement and coherence, traditionally studied in microscopic systems, have recently been observed and manipulated in macroscopic platforms. These phenomena play a critical role in understanding the boundary between classical and quantum physics and in developing quantum technologies such as superconducting qubits, optomechanical resonators, and atomic ensembles. This article reviews theoretical models, numerical simulations, and experimental techniques used to probe entanglement and coherence in large-scale systems. Five thematic outlines are presented, with one outline including two graphs illustrating (i) time evolution of entanglement in a macroscopic oscillator system, and (ii) coherence decay under environmental coupling. Applications, limitations, and future directions are discussed to provide a comprehensive perspective.