Abstract
In the context of bipartite bosonic systems, two notions of classicality of correlations can be defined: Pclassicality, based on the properties of the GlauberSudarshan Pfunction; and Cclassicality, 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 quantumoptical setting: the linear mixing at a beam splitter of a singlemode Gaussian state with a thermal reference state. Specifically, we show that almost all Pclassical input states generate outputs that are not Cclassical. Indeed, for the case of zero thermal reference photons, the more Pclassical resources at the input the less Cclassicality at the output. In addition, we show that the Pclassicality 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.
Original language  English 

Article number  062315 
Number of pages  11 
Journal  Physical Review A (Atomic, Molecular, and Optical Physics) 
Volume  91 
Issue number  6 
DOIs  
Publication status  Published  11 Jun 2015 
Keywords
 quantph
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Alessandro Ferraro
 School of Mathematics and Physics  Senior Lecturer
 Centre for Quantum Materials and Technologies (CQMT)
Person: Academic