Underlining some limitations of the statistical formalism in quantum mechanics

We show that two chosen ensembles of spin states, which are differently prepared but are described by the same density matrix in quantum mechanics, do not fully share the same measurable characteristics. One characteristic in which they differ is shown to be the variance of the spin along a given di...

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Bibliographic Details
Main Authors: Fratini, Filippo (Author) , Hayrapetyan, Armen (Author)
Format: Article (Journal)
Language:English
Published: 31 August 2011
In: Physica scripta
Year: 2011, Volume: 84, Issue: 3, Pages: 1-6
ISSN:1402-4896
DOI:10.1088/0031-8949/84/03/035008
Online Access:Verlag, lizenzpflichtig, Volltext: https://doi.org/10.1088/0031-8949/84/03/035008
Verlag, lizenzpflichtig, Volltext: https://dx.doi.org/10.1088/0031-8949/84/03/035008
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Author Notes:F. Fratini and A.G. Hayrapetyan
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Summary:We show that two chosen ensembles of spin states, which are differently prepared but are described by the same density matrix in quantum mechanics, do not fully share the same measurable characteristics. One characteristic in which they differ is shown to be the variance of the spin along a given direction. We conclude that the statistical description of an ensemble of states as given by its density matrix, although sufficient in many cases, should be considered incomplete, as it does not fully describe the measurable characteristics of the ensemble. A discussion a posteriori on the problem is provided.
Item Description:Gesehen am 06.03.2023
Physical Description:Online Resource
ISSN:1402-4896
DOI:10.1088/0031-8949/84/03/035008