Weak quantum discord
arXiv:1804.04983 · doi:10.1007/s11128-018-1963-1
Abstract
Originally introduced as the difference between two possible forms of quantum mutual information, quantum discord has posteriorly been shown to admit a formulation according to which it measures a distance between the state under scrutiny and the closest projectively measured (non-discordant) state. Recently, it has been shown that quantum discord results in higher values when projective measurements are substituted by weak measurements. This sounds paradoxical since weaker measurements should imply weaker disturbance and, thus, a smaller distance. In this work we solve this puzzle by presenting a quantifier and an underlying interpretation for what we call weak quantum discord. As a by-product, we introduce the notion of symmetrical weak quantum discord.
12 pages, 1 figure
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- Realism-based nonlocality: Invariance under local unitary operations and asymptotic decay for thermal correlated states
- High-dimensional monitoring and the emergence of realism via multiple observers
- Simulating the effect of weak measurements by a phase damping channel and determining different measures of bipartite correlations in nuclear magnetic resonance