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arXiv · 2605.23217

Two Operational Principles Single Out Quantum Theory

Kenji Nakahira
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Abstract

Quantum theory combines density matrices, Born probabilities, tensor-product composites, positive-operator-valued measures (POVMs), and quantum channels. In a finite-dimensional causal operational theory, we prove that two postulates suffice: local input-output statistics identify channels, and every state admits an equivalent-system purification, unique up to reversible dynamics. The full complex quantum formalism follows; every consistent probability rule is realized as a POVM, so measurement no-restriction is derived rather than assumed.

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Kenji Nakahira. 2026-05-22. Two Operational Principles Single Out Quantum Theory. https://arxiv.org/abs/2605.23217

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