A1 Refereed original research article in a scientific journal
Quantum instruments: I. Extreme instruments
Authors: Pellonpaa JP
Publisher: IOP PUBLISHING LTD
Publication year: 2013
Journal: Journal of Physics A: Mathematical and Theoretical
Journal name in source: JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
Journal acronym: J PHYS A-MATH THEOR
Article number: ARTN 025302
Number in series: 2
Volume: 46
Issue: 2
Number of pages: 16
ISSN: 1751-8113
DOI: https://doi.org/10.1088/1751-8113/46/2/025302
Abstract
The structure of completely positive quantum instruments is analyzed thoroughly. We characterize the extreme points of the convex set of instruments. The characterization holds also for nondiscrete instruments in infinite dimensions, and is applied to quantum observables, channels, and preparations which are special cases of instruments. We show that extreme instruments are discrete in finite dimensions.
The structure of completely positive quantum instruments is analyzed thoroughly. We characterize the extreme points of the convex set of instruments. The characterization holds also for nondiscrete instruments in infinite dimensions, and is applied to quantum observables, channels, and preparations which are special cases of instruments. We show that extreme instruments are discrete in finite dimensions.
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