Neutron optical test of completeness of quantum root-mean-square errors

While in classical mechanics the mean error of a measurement is solely caused by the measuring process (or device), in quantum mechanics the operator-based nature of quantum measurements has to be considered in the error measure as well. One of the major problems in quantum physics has been to gener...

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Bibliographic Details
Published in:npj quantum information 2021-06, Vol.7 (1), p.1-6, Article 106
Main Authors: Sponar, Stephan, Danner, Armin, Ozawa, Masanao, Hasegawa, Yuji
Format: Article
Language:English
Subjects:
639/766/483/2802
639/766/483/3924
Classical and Quantum Gravitation
Eigenvalues
Hilbert space
Noise
Physics
Physics and Astronomy
Probability distribution
Quantum Computing
Quantum Field Theories
Quantum Information Technology
Quantum Physics
Relativity Theory
Spintronics
String Theory
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Summary:While in classical mechanics the mean error of a measurement is solely caused by the measuring process (or device), in quantum mechanics the operator-based nature of quantum measurements has to be considered in the error measure as well. One of the major problems in quantum physics has been to generalize the classical root-mean-square error to quantum measurements to obtain an error measure satisfying both soundness (to vanish for any accurate measurements) and completeness (to vanish only for accurate measurements). A noise-operator-based error measure has been commonly used for this purpose, but it has turned out incomplete. Recently, Ozawa proposed an improved definition for a noise-operator-based error measure to be both sound and complete. Here, we present a neutron optical demonstration for the completeness of the improved error measure for both projective (or sharp) as well as generalized (or unsharp) measurements.
ISSN:2056-6387
2056-6387
DOI:10.1038/s41534-021-00437-8