New features of quantum discord uncovered by q-entropies

A.P. MAJTEY; A.R. PLASTINO; A. PLASTINO

PHYSICA A - STATISTICAL AND THEORETICAL PHYSICS

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2011 vol. 391 p. 2491 - 2499

0378-4371

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 going to 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 different of 1 one. If two quantum states A, B are such that D1(A) is larger than D1(B), this order-relation does not remain invariant under a change from D1 to Dq.