A1 Refereed original research article in a scientific journal
Wigner-Araki-Yanase theorem beyond conservation laws
Authors: Tukiainen M
Publisher: AMER PHYSICAL SOC
Publication year: 2017
Journal: Physical Review A
Journal name in source: PHYSICAL REVIEW A
Journal acronym: PHYS REV A
Article number: ARTN 012127
Volume: 95
Issue: 1
Number of pages: 7
ISSN: 2469-9926
eISSN: 2469-9934
DOI: https://doi.org/10.1103/PhysRevA.95.012127(external)
Web address : https://journals.aps.org/pra/pdf/10.1103/PhysRevA.95.012127(external)
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/19033159(external)
The ability to measure every quantum observable is ensured by a fundamental result in quantum measurement theory. Nevertheless, additive conservation laws associated with physical symmetries, such as the angular momentum conservation, may lead to restrictions on the measurability of the observables. Such limitations are imposed by the theorem of Wigner, Araki, and Yanase (WAY). In this paper a formulation of the WAY theorem is presented rephrasing the measurability limitations in terms of quantum incompatibility. This broader mathematical basis enables us to both capture and generalize the WAY theorem by allowing us to drop the assumptions of additivity and even conservation of the involved quantities. Moreover, we extend the WAY theorem to the general level of positive operator-valued measures.
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