Single- and two-mode quantumness at a beam splitter

Matteo Brunelli, Claudia Benedetti, Stefano Olivares, Alessandro Ferraro, Matteo G. A. Paris

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)
597 Downloads (Pure)


In the context of bipartite bosonic systems, two notions of classicality of correlations can be defined: P-classicality, based on the properties of the Glauber-Sudarshan P-function; and C-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 non-classicality 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 P-classical input states generate outputs that are not C-classical. Indeed, for the case of zero thermal reference photons, the more P-classical resources at the input the less C-classicality at the output. In addition, we show that the P-classicality at the input -- as quantified by the non-classical depth -- does instead determine quantitatively the potential of generating output entanglement. This endows the non-classical 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 languageEnglish
Article number062315
Number of pages11
JournalPhysical Review A (Atomic, Molecular, and Optical Physics)
Issue number6
Publication statusPublished - 11 Jun 2015


  • quant-ph


Dive into the research topics of 'Single- and two-mode quantumness at a beam splitter'. Together they form a unique fingerprint.

Cite this