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On the Descriptive Applicability of Global Quantum Superposition Architectural Considerations in Composite Systems

Danilo Tavella

Published Feb 10, 2026• 0 citations
Publisher

Abstract

Recent experimental advances in matter-wave interferometry have demonstrated quantum interference in increasingly large and massive composite objects, including nanoparticles composed of thousands of atoms. These results are often interpreted as evidence that quantum superposition can, in principle, scale arbitrarily with mass and size, with practical limitations arising primarily from environmental decoherence. This technical note argues that mass and size alone are insufficient criteria for assessing the applicability of global quantum superposition descriptions. It introduces a minimal, non-biological architectural distinction between systems that admit an effective global quantum description and systems whose internal organization renders such descriptions operationally ambiguous or illegitimate, even in the absence of significant external decoherence. The analysis does not propose any fundamental limitation on quantum mechanics, nor does it claim that global quantum states cease to exist. Instead, it focuses on the conditions under which global quantum descriptions remain meaningful and useful as effective representations. In architecturally composite systems, internal degrees of freedom may function as endogenous sources of decoherence, limiting the descriptive legitimacy of a single global quantum state. The contribution is diagnostic in nature and aims to clarify common ambiguities in discussions of the quantum–classical transition, the interpretation of large-scale interference experiments, and claims concerning the scalability of quantum superposition. No new physical principles or theoretical modifications are introduced.

DOI
10.5281/zenodo.18587763

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Recent experimental advances in matter-wave interferometry have demonstrated quantum interference in increasingly large and massive composite objects, including nanoparticles composed of thousands of atoms. These results are often interpreted as evidence that quantum superposition can, in principle, scale arbitrarily with mass and size, with practical limitations arising primarily from environmental decoherence. This technical note argues that mass and size alone are insufficient criteria for assessing the applicability of global quantum superposition descriptions. It introduces a minimal, non-biological architectural distinction between systems that admit an effective global quantum description and systems whose internal organization renders such descriptions operationally ambiguous or illegitimate, even in the absence of significant external decoherence. The analysis does not propose any fundamental limitation on quantum mechanics, nor does it claim that global quantum states cease to exist. Instead, it focuses on the conditions under which global quantum descriptions remain meaningful and useful as effective representations. In architecturally composite systems, internal degrees of freedom may function as endogenous sources of decoherence, limiting the descriptive legitimacy of a single global quantum state. The contribution is diagnostic in nature and aims to clarify common ambiguities in discussions of the quantum–classical transition, the interpretation of large-scale interference experiments, and claims concerning the scalability of quantum superposition. No new physical principles or theoretical modifications are introduced.
Abstract The quantum superposition principle is a fundamental concept of physics 1 and the basis of numerous quantum technologies 2,3 . Yet, it is still often regarded counterintuitive because we do not observe its key features on the macroscopic scales of our daily lives. It is, therefore, interesting to ask how quantum properties persist or change as we increase the size and complexity of objects 4 . A model test for this question can be realized by matter-wave interferometry, in which the motion of individual massive particles becomes delocalized and needs to be described by a wave function that spans regions far larger than the particle itself 5 . Over the years, this has been explored with a series of objects of increasing mass and complexity 6–9 and a growing community aims at pushing this to ever larger limits. Here we present an experimental platform that extends matter-wave interference to large metal clusters, a qualitatively new material class for quantum experiments. We specifically demonstrate quantum interference of sodium nanoparticles, which can each contain more than 7,000 atoms at masses greater than 170,000 Da. They propagate in a Schrödinger cat state with a macroscopicity 10 of μ = 15.5, surpassing previous experiments 5,9,11 by an order of magnitude.
This work presents a short conceptual analysis of quantum superposition with a focus on its physical realization rather than its mathematical formulation. While superposition is a fundamental principle in the formal structure of quantum mechanics, its physical manifestation depends on specific conditions related to interaction, coherence, and energy conservation. The paper emphasizes the distinction between mathematical possibility and physical representability. It argues that quantum superposition requires strict constraints to be physically maintained, and that in realistic environments—where interaction with internal degrees of freedom or external surroundings is unavoidable—coherent superposition cannot persist. The analysis also discusses extreme physical regimes, with particular attention to black hole event horizons. Instead of treating the event horizon as a region that naturally supports coherent quantum states, the paper examines it as a boundary where the physical representation of such states becomes problematic due to strong gravitational effects, redshift, and information scrambling. This discussion is intended as a conceptual clarification rather than a definitive statement about quantum gravity. The manuscript does not challenge the validity of quantum mechanics. Rather, it aims to clarify the physical conditions under which its core concepts can be meaningfully represented. The work is intended as a conceptual and critical note contributing to discussions in the foundations of quantum mechanics and the interpretation of quantum phenomena in extreme environments. KeywordsQuantum superposition; Physical representation; Decoherence; Event horizon; Foundations of quantum mechanics
Quantum mechanics provides an extraordinarily accurate description of microscopic systems, yet persistent conceptual difficulties arise when its superposition principle is naively extended to systems involving significant mass displacement. In particular, macroscopic superpositions imply the coexistence of distinct gravitational field configurations, raising questions of spacetime consistency rather than measurement or environmental interaction. This short note argues that the apparent breakdown of macroscopic superposition does not require a collapse mechanism or modification of quantum dynamics. Instead, it reflects a structural admissibility constraint: spacetime permits only one future-consistent geometry sourced by mass. From this perspective, the absence of macroscopic superpositions is a consequence of structural selection rather than dynamical collapse, reframing long-standing debates surrounding quantum mechanics and gravity.
The fact that gravitational environments cannot be shielded (since gravity is universal) makes them of great theoretical interest to decoherence mechanisms and to the quantum-to-classical transition. While past results seemed to indicate that graviton-induced decoherence of spatial superpositions happens only for macroscopic systems, recently it was shown that this mechanism can be enhanced through the system's own dynamical internal structure. In this work, we extend this analysis by including the interaction with a classical Newtonian potential. We show that, although the graviton bath alone dominates the mechanism for short times compared to a timescale established by the size of the quantum spatial superposition, the interaction between the gravitons and the internal degrees of freedom of the system renders decoherence inevitable in the long-time limit, even for microscopic masses. We also show that this mechanism is slightly slowed down by the interplay with the classical Newtonian potential, which, for systems without dynamical internal degrees of freedom, can even lead to recoherence-like behaviour, at least in principle.
We propose a method to prepare and verify spatial quantum superpositions of a nanometer-sized object separated by distances of the order of its size. This method provides unprecedented bounds for objective collapse models of the wave function by merging techniques and insights from cavity quantum optomechanics and matter-wave interferometry. An analysis and simulation of the experiment is performed taking into account standard sources of decoherence. We provide an operational parameter regime using present-day and planned technology.
We propose a new interpretation of quantum mechanics, the core idea of which is that quantum superposition states are not mysterious physical entities, but rather the joint distribution of classical information obtained by local observers in a composite system. We assume that all systems are equivalent, and there is no fundamental distinction between "observer" and "observed". When multiple local observers independently observe the same system, if their observation results agree, the composite observer obtains a classical particle-like fact; if their observation results diverge, the composite observer obtains quantum wave-like behavior (a superposition state). We demonstrate that this "persuasion theory"—namely, that only when local observers reach an agreement can they persuade the composite observer—can naturally derive the formalism of quantum mechanics and perfectly explain the wave-particle duality in the double-slit interference experiment. This theory interprets quantum mechanics as a theory concerning the classical information mutually possessed by physical systems and their compositional relationships, and this description is complete.