Classical and quantum correlations under decoherence

Abstract

Recently some authors have pointed out that there exist nonclassical correlations which are more general, and possibly more fundamental, than entanglement. For these general quantum correlations and their classical counterparts, under the action of decoherence, we identify three general types of dynamics that include a peculiar sudden change in their decay rates. We show that, under suitable conditions, the classical correlation is unaffected by decoherence. Such dynamic behavior suggests an operational measure of both classical and quantum correlations that can be computed without any extremization procedure.Comment: Published versio

Spotlighting quantum critical points via quantum correlations at finite temperatures

“…The behavior of TQD in this case is related to the minimization process of the quantum conditional entropy (A.2). We observe that for finite T there is an exchange in the functions that minimize the conditional entropy which in turn leads to a sudden change in TQD [33] Moving to the cases where h > 0 we keep the same set of parameters of Fig. 2 but the value of the external magnetic field.…”

Quantum correlations as precursors of entanglement

“…The finitetime disappearance of entanglement, sometimes called "sudden-death of entanglement" [28,33] was experimentally demonstrated by Almeida et al [32]. The dynamics of quantum correlations other then entanglement has also been analyzed, both theoretically [34,35] and experimentally [36].…”

Sudden change in quantum and classical correlations and the Unruh effect

“…Recent results showing that almost all (separable) quantum states actually have such nonclassical correlations [3] and that they can improve some computational tasks in comparison to when classical states are used [4,5] reinforce the relevance of such an issue. As a result, the last few years have witnessed an increasing number of articles discussing the quantification of these correlations [1,2,[6][7][8], their behavior under decoherence [9][10][11][12], and their relevance for quantum phase transitions [13][14][15][16].…”