Discord of response
- Author(s)
- W. Roga, S. M. Giampaolo, F. Illuminati
- Abstract
The presence of quantum correlations in a quantum state is related to the stateʼs response to local unitary perturbations. Such a response is quantified by the distance between the unperturbed and perturbed states, minimized with respect to suitably identified sets of local unitary operations. In order to be a bona fide measure of quantum correlations, the distance function must be chosen among those that are contractive under completely positive and trace preserving (CPTP) maps. The most relevant instances of such physically well-behaved metrics include the trace, the Bures, and the Hellinger distance. To each of these metrics one can associate the corresponding discord of response, namely the trace, or Hellinger, or Bures minimum distance from the set of unitarily perturbed states. All these three discords of response satisfy the basic axioms for a proper measure of quantum correlations. In the present work we focus in particular on the Bures distance, which enjoys the unique property of being both Riemannian and contractive under CPTP maps, and admits important operational interpretations in terms of state distinguishability. We compute analytically the Bures discord of response for two-qubit states with maximally mixed marginals and we compare it with the corresponding Bures geometric discord, namely the geometric measure of quantum correlations defined as the Bures distance from the set of classical-quantum states. Finally, we investigate and identify the maximally quantum correlated two-qubit states according to the Bures discord of response. These states exhibit a remarkable nonlinear dependence on the global state purity.
- Organisation(s)
- Particle Physics
- External organisation(s)
- Università degli Studi di Salerno, Istituto Nazionale di Fisica Nucleare (INFN), Roma, National Interuniversity Consortium for the Physical Sciences of Matter
- Journal
- Journal of Physics A: Mathematical and Theoretical
- Volume
- 47
- No. of pages
- 18
- ISSN
- 1751-8113
- DOI
- https://doi.org/10.1088/1751-8113/47/36/365301
- Publication date
- 09-2014
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 103034 Particle physics, 103019 Mathematical physics
- Keywords
- ASJC Scopus subject areas
- Physics and Astronomy(all), Statistical and Nonlinear Physics, Statistics and Probability, Mathematical Physics, Modelling and Simulation
- Portal url
- https://ucris.univie.ac.at/portal/en/publications/discord-of-response(fbac9c4c-8a63-47a1-9479-387ed81ef6d9).html