Gao, Shan (2026) From Joint to Single-System Psi-Onticity Without Preparation Independence. Foundations of Physics, 56 (7). ISSN 1572-9516

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Abstract

The Pusey–Barrett–Rudolph (PBR) theorem establishes $\psi$-onticity for individual quantum systems, but its standard formulation relies on the Preparation Independence Postulate (PIP). This has led to a prevalent view that rejecting PIP leaves open the possibility of $\psi$-epistemic models for individual systems. In this work, we show that this understanding is incomplete: once the PBR theorem establishes $\psi$-onticity for composite systems prepared in product states, the $\psi$-onticity of the individual subsystems follows directly from the tensor-product structure of quantum mechanics, without invoking PIP or any further auxiliary assumptions. This result removes a key auxiliary assumption from the PBR theorem, closes a persistent loophole for preserving $\psi$-epistemic models, and strengthens the conceptual foundations of $\psi$-ontology.

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Item Type:	Published Article or Volume
Creators:	Creators Email ORCID Gao, Shan sgao7319@uni.sydney.edu.au
Keywords:	Wave function; PBR Theorem; preparation independence; tensor product; psi-ontology
Subjects:	General Issues > Scientific Metaphysics Specific Sciences > Probability/Statistics Specific Sciences > Physics > Quantum Mechanics
Depositing User:	Prof. Shan Gao
Date Deposited:	23 Jan 2026 13:42
Last Modified:	23 Jan 2026 13:42
Item ID:	27986
Journal or Publication Title:	Foundations of Physics
Publisher:	Springer
Official URL:	https://link.springer.com/article/10.1007/s10701-0...
DOI or Unique Handle:	10.1007/s10701-025-00910-w
Subjects:	General Issues > Scientific Metaphysics Specific Sciences > Probability/Statistics Specific Sciences > Physics > Quantum Mechanics
Date:	23 January 2026
Volume:	56
Number:	7
ISSN:	1572-9516
URI:	https://philsci-archive.pitt.edu/id/eprint/27986

Available Versions of this Item

• The PBR Theorem Requires No Preparation Independence. (deposited 15 Jul 2025 13:09)
  • From Joint to Single-System Psi-Onticity Without Preparation Independence. (deposited 23 Jan 2026 13:42) [Currently Displayed]

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