New features of quantum discord uncovered by q-entropies
Abstract
The notion of quantum discord introduced by Ollivier and Zurek [Phys. Rev. Lett 88 (2001) 017901] (see also Henderson and Vedral [J. Phys. A 34 (2001) 6899] ) has attracted increasing attention, in recent years, as an entropic quantifier of non-classical features pertaining to the correlations exhibited by bipartite quantum systems. Here we generalize the notion so as to encompass power-law q-entropies (that reduce to the standard Shannon entropy in the limit q→1) and study the concomitant consequences. The ensuing, new discord-like measures we advance describe aspects of non-classicality that are different from those associated with the standard quantum discord. A particular manifestation of this difference concerns a feature related to order. Let D1 stand for the standard, Shannon-based discord measure and Dq for the q≠1 one. If two quantum states A,B are such that D1(A)>D1(B), this order-relation does not remain invariant under a change from D1 to Dq.
- Publication:
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Physica A Statistical Mechanics and its Applications
- Pub Date:
- April 2012
- DOI:
- 10.1016/j.physa.2011.11.062
- arXiv:
- arXiv:1112.4957
- Bibcode:
- 2012PhyA..391.2491M
- Keywords:
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- Quantum Physics
- E-Print:
- 11 pages, 8 figures