Entanglement without Quantum Mechanics: Operational Constraints on the Quantum Signature

• URL: http://arxiv.org/abs/2512.14834v1
• Date: Tue, 16 Dec 2025 19:00:06 GMT
• Title: Entanglement without Quantum Mechanics: Operational Constraints on the Quantum Signature
• Authors: Samuel Schlegel, Borivoje Dakić, Flavio Del Santo,
• Abstract summary: Entanglement is often regarded as an inherently quantum feature.<n>We show that under restricted operational access, classical correlations can appear nonseparable.
• Score: 0.0
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: Entanglement is often regarded as an inherently quantum feature. We show that this does not have to be the case: under restricted operational access, classical correlations can appear nonseparable when expressed in the formalism of quantum mechanics. If an observer is limited to a constrained set of measurements and transformations, certain classical phase-space distributions can mimic entanglement-like behaviours. Imposing positivity of the associated Hilbert space operator as a physicality requirement removes some of these representational artifacts, revealing a regime in which nonseparability is genuine but still reproducible by classical models. Only when the operational restrictions on the observer are lifted further--allowing operational tests of measurement incompatibility or other nonclassical signatures--does one obtain entanglement that can no longer be captured by any classical description. This operational hierarchy distinguishes classical artifacts, classically reproducible nonseparability, and genuine entanglement.

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