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On the Operational Inadmissibility of Macroscopic Superpositions

Radu Necsanu

Published Jan 29, 2026• 0 citations
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Abstract

Operational Inadmissibility of Macroscopic Wavefunctions Author: Radu Necsanu ORCID: https://orcid.org/0009-0009-1281-9180 DOI: https://doi.org/10.5281/zenodo.18408307 Abstract This paper establishes an operational criterion for when it is admissible to ascribe a single pure quantum state to a macroscopic collective degree of freedom. Working strictly within standard quantum mechanics, it delineates the conditions under which environmental interactions suppress the reduced coherence required for such an attribution at any finite experimental resolution. The result is intended to clarify the operational limits of macroscopic superposition claims without invoking modified dynamics or interpretive assumptions.

DOI
10.5281/zenodo.18408306

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Operational Inadmissibility of Macroscopic Wavefunctions Author: Radu Necsanu ORCID: https://orcid.org/0009-0009-1281-9180 DOI: https://doi.org/10.5281/zenodo.18408307 Abstract This paper establishes an operational criterion for when it is admissible to ascribe a single pure quantum state to a macroscopic collective degree of freedom. Working strictly within standard quantum mechanics, it delineates the conditions under which environmental interactions suppress the reduced coherence required for such an attribution at any finite experimental resolution. The result is intended to clarify the operational limits of macroscopic superposition claims without invoking modified dynamics or interpretive assumptions.
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This work proposes an operational framework, denoted OFID-G, to investigate whether quantum coherence remains fully reconstructible from locally accessible information, even when global unitary evolution is preserved. The framework is formulated within the Ontological Framework of Imbricated Degrees (OFID), in which physical states may involve degrees of freedom that are not fully accessible within a given local observational regime. Within this perspective, OFID-G defines a possible structural limitation on the local accessibility of coherence, without introducing any modification to quantum dynamics. The central concept is regime-dependent reconstructibility: coherence is said to be reconstructible if a single recovery operation, fixed by calibration alone, can operationally recover it across a tomographically informative family of preparations, and non-reconstructible if a persistent limitation remains despite such procedures. This state-independent formulation anchors the criterion in the theory of approximate recoverability of quantum channels. Rather than predicting a specific mechanism, the framework defines a falsifiable structural criterion distinguishing reconstructible and non-reconstructible regimes, based on controlled variation of physically relevant parameters. The approach remains fully compatible with standard quantum mechanics and does not invoke collapse models or deviations from unitarity. Its empirical content lies in testing whether all observed decoherence effects can be fully accounted for by known environmental mechanisms. This provides a minimal and operational test of the completeness of standard decoherence modeling, shifting the focus from dynamical mechanisms to structural limitations of information accessibility. The framework is developed within the OFID research program (DOI: 10.5281/zenodo.18868538); its concrete experimental realization is developed in a companion operational paper (DOI: 10.5281/zenodo.19351945). Project page :https://alexsasfrance.github.io/OFID-framework/
Refinement-Consistent Event Binning Forces the Born Rule Author: Radu Necsanu ORCID: https://orcid.org/0009-0009-1281-9180 DOI: https://doi.org/10.5281/zenodo.18408230 Abstract Within standard quantum mechanics, we model sharp measurement outcomes by a finite projective measurement {Pᵢ} and interpret events as finite unions of outcome bins represented by their coarse-grained projector. Assuming only (i) the ordinary probability axioms on finite event sets, (ii) representation invariance under joint unitary changes of basis and phase redefinitions, and (iii) refinement-consistency—namely, that the probability of a coarse event depends only on its projector and is invariant under internal refinements of the event and its complement—we show that the unique compatible probability rule in dim(H) ≥ 3 is the Born rule p(P|ψ)=⟨ψ|P|ψ⟩. With the standard preparation-mixture consistency condition, the rule extends uniquely to mixed states and POVMs via p(E|ρ)=Tr(ρE).
What are the physical conditions required for agency?Recent work has rigorously shown that purely unitary, coherence-preserving quantum dynamics are insufficient to support deliberation, comparison of counterfactual actions, and reliable action selection. These results establish a genuine no-go theorem for agency in a strictly quantum-coherent regime.This paper provides a structural completion of that no-go result. Rather than challenging its correctness, the analysis identifies the underlying assumption on which it rests: that unitarity alone is sufficient as an admissibility criterion for decision endpoints. We show that this assumption is incomplete.Working within the Tier-0 closure framework, physical lawfulness is characterized by closure-stable fixed points selected by structural constraints rather than by unconstrained dynamical evolution. Within this framework, coherent quantum states may function as intermediate computational or representational states but are excluded as lawful endpoints for records, decisions, and control.Applying closure stability to quantum systems yields a classical decision subspace without introducing new dynamics, observer-dependent postulates, or interpretation-specific assumptions. The paper further shows that agency requires a closure-stable internal selection process capable of consistent expected-utility comparison. Imposing closure compatibility rigidly fixes the standard quadratic Born probability rule as the only weighting compatible with stability, representation-independence, and admissibility-preserving re-expression.Together, these results integrate agency into the same structural framework that accounts for quantum measurement and probability. The absence of agency in purely quantum-coherent models is shown to reflect an under-constrained admissibility regime rather than a fundamental limitation of quantum theory. Lawful agency emerges as a closure-stable property of coupled agent–world dynamics, fully consistent with standard quantum mechanics.This work clarifies the physical limits of purely quantum models of decision, sharpens existing no-go arguments, and provides a mathematically explicit foundation for agency grounded in structural admissibility rather than interpretation. https://doi.org/10.5281/zenodo.18028427
Abstract Identifying which quantum states qualify as macroscopic superpositions remains a fundamental challenge in quantum physics, as no universally accepted operational criterion currently exists. In this work we introduce a dynamical criterion for macroscopic quantum superposition based on the continuous-measurement-based measure of quantum superposition together with the principle of macrorealism. The key idea is to characterize macroscopicity through the rate of purity decay of the quantum state under continuous monitoring, which quantifies the susceptibility of quantum coherence to classicalizing mechanisms. Two classes of macrorealistic dynamics are considered: environmental decoherence described by a Lindblad master equation (class A) and objective collapse dynamics in the continuous spontaneous localization model (class B). Applying this framework to an optomechanical oscillator, we show that the emergence of macroscopic superposition depends on the competition between measurement-induced decoherence and the macrorealistic mechanism. In class A the relevant contributions increase with excitation number, whereas in class B large excitation numbers can suppress macroscopicity. Unlike many existing macroscopicity measures based solely on phase-space structure or decoherence times, the present criterion directly relates macroscopicity to experimentally accessible parameters in continuous quantum measurement.