Incompatibility of quantum instruments

Quantum instruments describe outcome probability as well as state change induced by measurement of a quantum system. Incompatibility of two instruments, i. e. the impossibility to realize them simultaneously on a given quantum system, generalizes incompatibility of channels and incompatibility of po...

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Main Authors: Leevi Leppäjärvi, Michal Sedlák
Format: Article
Language:English
Published: Verein zur Förderung des Open Access Publizierens in den Quantenwissenschaften 2024-02-01
Series:Quantum
Online Access:https://quantum-journal.org/papers/q-2024-02-12-1246/pdf/
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author Leevi Leppäjärvi
Michal Sedlák
author_facet Leevi Leppäjärvi
Michal Sedlák
author_sort Leevi Leppäjärvi
collection DOAJ
description Quantum instruments describe outcome probability as well as state change induced by measurement of a quantum system. Incompatibility of two instruments, i. e. the impossibility to realize them simultaneously on a given quantum system, generalizes incompatibility of channels and incompatibility of positive operator-valued measures (POVMs). We derive implications of instrument compatibility for the induced POVMs and channels. We also study relation of instrument compatibility to the concept of non-disturbance. Finally, we prove equivalence between instrument compatibility and postprocessing of certain instruments, which we term complementary instruments. We illustrate our findings on examples of various classes of instruments.
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spelling doaj.art-bab6d7770e6d417b841bce435bb1035e2024-02-12T13:54:09ZengVerein zur Förderung des Open Access Publizierens in den QuantenwissenschaftenQuantum2521-327X2024-02-018124610.22331/q-2024-02-12-124610.22331/q-2024-02-12-1246Incompatibility of quantum instrumentsLeevi LeppäjärviMichal SedlákQuantum instruments describe outcome probability as well as state change induced by measurement of a quantum system. Incompatibility of two instruments, i. e. the impossibility to realize them simultaneously on a given quantum system, generalizes incompatibility of channels and incompatibility of positive operator-valued measures (POVMs). We derive implications of instrument compatibility for the induced POVMs and channels. We also study relation of instrument compatibility to the concept of non-disturbance. Finally, we prove equivalence between instrument compatibility and postprocessing of certain instruments, which we term complementary instruments. We illustrate our findings on examples of various classes of instruments.https://quantum-journal.org/papers/q-2024-02-12-1246/pdf/
spellingShingle Leevi Leppäjärvi
Michal Sedlák
Incompatibility of quantum instruments
Quantum
title Incompatibility of quantum instruments
title_full Incompatibility of quantum instruments
title_fullStr Incompatibility of quantum instruments
title_full_unstemmed Incompatibility of quantum instruments
title_short Incompatibility of quantum instruments
title_sort incompatibility of quantum instruments
url https://quantum-journal.org/papers/q-2024-02-12-1246/pdf/
work_keys_str_mv AT leevileppajarvi incompatibilityofquantuminstruments
AT michalsedlak incompatibilityofquantuminstruments