Order preserving maps on quantum measurements

We study the partially ordered set of equivalence classes of quantum measurements endowed with the post-processing partial order. The post-processing order is fundamental as it enables to compare measurements by their intrinsic noise and it gives grounds to define the important concept of quantum in...

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Main Authors: Teiko Heinosaari, Maria Anastasia Jivulescu, Ion Nechita
Format: Article
Language:English
Published: Verein zur Förderung des Open Access Publizierens in den Quantenwissenschaften 2022-11-01
Series:Quantum
Online Access:https://quantum-journal.org/papers/q-2022-11-10-853/pdf/
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author Teiko Heinosaari
Maria Anastasia Jivulescu
Ion Nechita
author_facet Teiko Heinosaari
Maria Anastasia Jivulescu
Ion Nechita
author_sort Teiko Heinosaari
collection DOAJ
description We study the partially ordered set of equivalence classes of quantum measurements endowed with the post-processing partial order. The post-processing order is fundamental as it enables to compare measurements by their intrinsic noise and it gives grounds to define the important concept of quantum incompatibility. Our approach is based on mapping this set into a simpler partially ordered set using an order preserving map and investigating the resulting image. The aim is to ignore unnecessary details while keeping the essential structure, thereby simplifying e.g. detection of incompatibility. One possible choice is the map based on Fisher information introduced by Huangjun Zhu, known to be an order morphism taking values in the cone of positive semidefinite matrices. We explore the properties of that construction and improve Zhu's incompatibility criterion by adding a constraint depending on the number of measurement outcomes. We generalize this type of construction to other ordered vector spaces and we show that this map is optimal among all quadratic maps.
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spelling doaj.art-af668f7c11b94bd3a44da68ebf6ac82c2022-12-22T03:35:40ZengVerein zur Förderung des Open Access Publizierens in den QuantenwissenschaftenQuantum2521-327X2022-11-01685310.22331/q-2022-11-10-85310.22331/q-2022-11-10-853Order preserving maps on quantum measurementsTeiko HeinosaariMaria Anastasia JivulescuIon NechitaWe study the partially ordered set of equivalence classes of quantum measurements endowed with the post-processing partial order. The post-processing order is fundamental as it enables to compare measurements by their intrinsic noise and it gives grounds to define the important concept of quantum incompatibility. Our approach is based on mapping this set into a simpler partially ordered set using an order preserving map and investigating the resulting image. The aim is to ignore unnecessary details while keeping the essential structure, thereby simplifying e.g. detection of incompatibility. One possible choice is the map based on Fisher information introduced by Huangjun Zhu, known to be an order morphism taking values in the cone of positive semidefinite matrices. We explore the properties of that construction and improve Zhu's incompatibility criterion by adding a constraint depending on the number of measurement outcomes. We generalize this type of construction to other ordered vector spaces and we show that this map is optimal among all quadratic maps.https://quantum-journal.org/papers/q-2022-11-10-853/pdf/
spellingShingle Teiko Heinosaari
Maria Anastasia Jivulescu
Ion Nechita
Order preserving maps on quantum measurements
Quantum
title Order preserving maps on quantum measurements
title_full Order preserving maps on quantum measurements
title_fullStr Order preserving maps on quantum measurements
title_full_unstemmed Order preserving maps on quantum measurements
title_short Order preserving maps on quantum measurements
title_sort order preserving maps on quantum measurements
url https://quantum-journal.org/papers/q-2022-11-10-853/pdf/
work_keys_str_mv AT teikoheinosaari orderpreservingmapsonquantummeasurements
AT mariaanastasiajivulescu orderpreservingmapsonquantummeasurements
AT ionnechita orderpreservingmapsonquantummeasurements