Publication Details

Postprocessing of quantum instruments

LEPPÄJÄRVI, L.; SEDLÁK, M. Postprocessing of quantum instruments. Physical Review A, 2021, vol. 103, no. 2, p. 1-13. ISSN: 2469-9926.
Czech title
Postprocesování kvantových instrumentů
Type
journal article
Language
English
Authors
Leppäjärvi Leevi
Sedlák Michal, Mgr., Ph.D.
URL
Keywords

quantum measurement, quantum instrument, sequence of measurements, POVM

Abstract

Studying sequential measurements is of the utmost importanceto both the foundational aspects of quantum theory and the practicalimplementations of quantum technologies, with both of these applications beingabstractly described by the concatenation of quantum instruments into asequence of certain length. In general, the choice of instrument at any givenstep in the sequence can be conditionally chosen based on the classical resultsof all preceding instruments. For two instruments in a sequence we consider theconditional second instrument as an effective way of post-processing the firstinstrument into a new one. This is similar to how a measurement described by apositive operator-valued measure (POVM) can be post-processed into another byway of classical randomization of its outcomes using a stochastic matrix. Inthis work we study the post-processing relation of instruments and the partialorder it induces on their equivalence classes. We characterize the greatest andthe least element of this order, give examples of post-processings betweendifferent types of instruments and draw connections between post-processings ofsome of these instruments and their induced POVMs.

Published
2021
Pages
1–13
Journal
Physical Review A, vol. 103, no. 2, ISSN 2469-9926
DOI
UT WoS
000621592100006
EID Scopus
BibTeX
@article{BUT168548,
  author="Leevi {Leppäjärvi} and Michal {Sedlák}",
  title="Postprocessing of quantum instruments",
  journal="Physical Review A",
  year="2021",
  volume="103",
  number="2",
  pages="1--13",
  doi="10.1103/PhysRevA.103.022615",
  issn="2469-9926",
  url="https://journals.aps.org/pra/pdf/10.1103/PhysRevA.103.022615"
}
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