1202.1959 (Manuel Gessner et al.)

Correlations in quantum states and the local creation of quantum discord    [PDF]

Manuel Gessner, Elsi-Mari Laine, Heinz-Peter Breuer, Jyrki Piilo

Quantum discord is usually referred to as a measure for quantum correlations.
In the search of the fundamental resource to gain a quantum advantage in
quantum information applications, quantum discord is considered a promising
candidate. In this paper we present an alternative view on quantum correlations
in terms of the rank of the correlation matrix as introduced in [Phys. Rev.
Lett. 105, 190502 (2010)]. According to our analysis, information about the
quantum discord does not necessarily determine the amount of quantum
correlations but rather the quantumness of the state. Nonzero quantum discord
is only a necessary but not a sufficient condition for correlations above the
classically achievable limit. This becomes clear when we consider states of
nonzero discord which can be created from zero discord states only by a single
local operation. We further show that the set of these states has measure zero.

View original: http://arxiv.org/abs/1202.1959