2015/07/27 by Ognyan Oreshkov, Nicolas J. Cerf · 1 citation
Arts and Humanities · Mathematics · Medicine · Physics and Astronomy · #Biofield Effects and Biophysics #Mathematics #Philosophy and History of Science #Physics #Probabilistic logic #Quantum #Quantum Mechanics and Applications #Quantum mechanics #Statistical physics #Statistics #Symmetry (geometry) #T-symmetry #Theoretical physics #gr-qc #hep-th #quant-ph
paper · pdf · doi:10.1038/nphys3414
published as Nature Phys. 11, 853-858 (2015) · 17 pages, 5 figures
openalex publication_date 2015/07/27 · arxiv created 2016/07/29 · arxiv updated 2016/08/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The symmetry of quantum theory under time reversal has long been a subject of controversy because the transition probabilities given by Born's rule do not apply backward in time. Here, we resolve this problem within a rigorous operational probabilistic framework. We argue that reconciling time reversal with the probabilistic rules of the theory requires a notion of operation that permits realizations via both pre- and post-selection. We develop the generalized formulation of quantum theory that stems from this approach and give a precise definition of time-reversal symmetry, emphasizing a previously overlooked distinction between states and effects. We prove an analogue of Wigner's theorem, which characterizes all allowed symmetry transformations in this operationally time-symmetric quantum theory. Remarkably, we find larger classes of symmetry transformations than those assumed before. This suggests a possible direction for search of extensions of known physics.