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Continuous Variable Entangled States in type-II OPOs – Characterizing their quantumness in a noisy environment

Alberto Porzio

à 14h en salle C. Brot

A single type-II OPO generates a pair of CV entangled states. Such a kind of entangled states strongly differ from the spin-like system that the quantum communication community mostly use for realising complex quantum protocols. Nevertheless, CV states present some features that can lead, in the near future, to beating some of the intrinsic limits in single photon systems. Starting from a short review on the definition of quantum CV states and on the experimental source based on type-II OPO we discuss several quantum measure used for characterizing such states and experimentally show their behaviour in a lossy transmission. We found that while the simplest form of quantum correlation once set it never disappear, stronger property, like Bell-type and steering capability, get lost during the propagation. In the last part of the seminar, we will also discuss the role of thermal noise contribution in preserving and/or enhancing Gaussian discord, a quantity able to discriminate classical from quantum correlations.