Why Should We Care About Quantum Discord?

  • Aharon BrodutchEmail author
  • Daniel R. Terno
Part of the Quantum Science and Technology book series (QST)


Entanglement is a central feature of quantum theory. Mathematical properties and physical applications of pure state entanglement make it a template to study quantum correlations. However, an extension of entanglement measures to mixed states in terms of separability does not always correspond to all the operational aspects. Quantum discord measures allow an alternative way to extend the idea of quantum correlations to mixed states. In many cases these extensions are motivated by physical scenarios and quantum information protocols. In this chapter we discuss several settings involving correlated quantum systems, ranging from distributed gates to detectors testing quantum fields. In each setting we show how entanglement fails to capture the relevant features of the correlated system, and discuss the role of discord as a possible alternative.



A part of this work was done when AB was at the Institute for Quantum Computing and the Department of Physics and Astronomy at the University of Waterloo. AB was supported by NSERC, Industry Canada, CIFAR and a fellowship from the Center for Quantum Information and Quantum Control.


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Copyright information

© Springer International Publishing AG 2017

Authors and Affiliations

  1. 1.Center for Quantum Information and Quantum ControlUniversity of TorontoTorontoCanada
  2. 2.Department of Physics, Institute for Optical SciencesUniversity of TorontoTorontoCanada
  3. 3.The Edward S. Rogers Department of Electrical and Computer EngineeringUniversity of TorontoTorontoCanada
  4. 4.Department of Physics and AstronomyMacquarie UniversitySydneyAustralia

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