Two Operational Principles Single Out Quantum Theory
Quantum Physics
2026-05-25 v1
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.
Cite
@article{arxiv.2605.23217,
title = {Two Operational Principles Single Out Quantum Theory},
author = {Kenji Nakahira},
journal= {arXiv preprint arXiv:2605.23217},
year = {2026}
}