Hierarchy of efficiently computable and faithful lower bounds to quantum discord

Marco Piani

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4 Citations (Scopus)
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Quantum discord expresses a fundamental non-classicality of correlations that is more general than entanglement, but that, in its standard definition, is not easily evaluated. We derive a hierarchy of computationally efficient lower bounds to the standard quantum discord. Every non-trivial element of the hierarchy constitutes by itself a valid discord-like measure, based on a fundamental feature of quantum correlations: their lack of shareability. Our approach emphasizes how the difference between entanglement and discord depends on whether shareability is intended as a static property or as a dynamical process.
Original languageEnglish
Article number080401
Number of pages6
JournalPhysical Review Letters
Issue number8
Publication statusPublished - 15 Aug 2016


  • quantum discord
  • quantum separability
  • quantum fidelity
  • hierarchy
  • quantum correlations
  • shareability
  • a semidefinite programming
  • entanglement


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