Abstract
In the context of bipartite bosonic systems, two notions of classicality of correlations can be defined: classicality, based on the properties of the Glauber-Sudarshan function; and classicality, based on the entropic quantum discord. It has been shown that these two notions are maximally inequivalent in a static (metric) sense, as they coincide only on a set of states of zero measure. We extend and reinforce quantitatively this inequivalence by addressing the dynamical relation between these types of nonclassicality in a paradigmatic quantum-optical setting: the linear mixing at a beam splitter of a single-mode Gaussian state with a thermal reference state. Specifically, we show that almost all -classical input states generate outputs that are not classical. Indeed, for the case of zero thermal reference photons, the more -classical resources at the input the less classicality at the output. In addition, we show that the classicality at the input—as quantified by the nonclassical depth—does instead determine quantitatively the potential of generating output entanglement. This endows the nonclassical depth with a new operational interpretation: it gives the maximum number of thermal reference photons that can be mixed at a beam splitter without destroying the output entanglement.
3 More- Received 23 February 2015
DOI:https://doi.org/10.1103/PhysRevA.91.062315
©2015 American Physical Society