A1 Refereed original research article in a scientific journal
Geometric characterization of true quantum decoherence
Authors: Kayser, Julius; Luoma, Kimmo; Strunz, Walter T.
Publisher: AMER PHYSICAL SOC
Publication year: 2015
Journal: Physical Review A
Journal name in source: PHYSICAL REVIEW A
Journal acronym: PHYS REV A
Article number: ARTN 052117
Volume: 92
Number of pages: 5
ISSN: 1050-2947
DOI: https://doi.org/10.1103/PhysRevA.92.052117
Web address : https://journals.aps.org/pra/abstract/10.1103/PhysRevA.92.052117
Abstract
Surprisingly often decoherence is due to classical fluctuations of ambient fields and may thus be described in terms of random unitary (RU) dynamics. However, there are decoherence channels where such a representation cannot exist. Based on a simple and intuitive geometric measure for the distance of an extremal channel to the convex set of RU channels we are able to characterize the set of true quantum phase-damping channels. Remarkably, using the Caley-Menger determinant, our measure may be assessed directly from the matrix representation of the channel. We find that the channel of maximum quantumness is closely related to a symmetric, informationally complete positive operator-valued measure on the environment. Our findings are in line with numerical results based on the entanglement of assistance.
Surprisingly often decoherence is due to classical fluctuations of ambient fields and may thus be described in terms of random unitary (RU) dynamics. However, there are decoherence channels where such a representation cannot exist. Based on a simple and intuitive geometric measure for the distance of an extremal channel to the convex set of RU channels we are able to characterize the set of true quantum phase-damping channels. Remarkably, using the Caley-Menger determinant, our measure may be assessed directly from the matrix representation of the channel. We find that the channel of maximum quantumness is closely related to a symmetric, informationally complete positive operator-valued measure on the environment. Our findings are in line with numerical results based on the entanglement of assistance.
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