Quantum Theory From Five Reasonable Axioms
Abstract
The usual formulation of quantum theory is based on rather obscure axioms (employing complex Hilbert spaces, Hermitean operators, and the trace rule for calculating probabilities). In this paper it is shown that quantum theory can be derived from five very reasonable axioms. The first four of these are obviously consistent with both quantum theory and classical probability theory. Axiom 5 (which requires that there exists continuous reversible transformations between pure states) rules out classical probability theory. If Axiom 5 (or even just the word "continuous" from Axiom 5) is dropped then we obtain classical probability theory instead. This work provides some insight into the reasons quantum theory is the way it is. For example, it explains the need for complex numbers and where the trace formula comes from. We also gain insight into the relationship between quantum theory and classical probability theory.
Cite
@article{arxiv.quant-ph/0101012,
title = {Quantum Theory From Five Reasonable Axioms},
author = {Lucien Hardy},
journal= {arXiv preprint arXiv:quant-ph/0101012},
year = {2007}
}
Comments
34 pages. Version 4: Improved proofs of K=N^r and D=D^T. Discussion of state update rule after measurement added. Various clarifications in proofs Version 2: Axiom 2 modified and corresponding corrections made to proof in Sec. 8.1. Typos and minor errors fixed