Eur. Phys. J. Special Topics 160, 1-10 (2008)
DOI: 10.1140/epjst/e2008-00704-1

Quantum and classical correlations in tripartite Gaussian states of light

A. Allevi¹, M. Bondani², M.G.A. Paris^{3, 4, 5} and A. Andreoni<sup>1

1</sup>  CNR-INFM-CNISM, Dipartimento di Fisica e Matematica, Università degli Studi dell'Insubria, 22100 Como, Italy
²  National Laboratory for Ultrafast and Ultraintense Optical Science - CNR-INFM, 22100 Como, Italy
³  Dipartimento di Fisica, Università di Milano, 20133 Milano, Italy
⁴  CNISM, U.d.R. Milano Università, 20133 Milano, Italy
⁵  Institute for Scientific Interchange Foundation, 10133 Torino, Italy

alessia.allevi@uninsubria.it

Published online: 18 June 2008

Abstract
We demonstrate an optical scheme involving two interlinked nonlinear interactions taking place simultaneously in a second-order nonlinear crystal. The three-mode output state is fully inseparable and endowed with perfect photon-number correlations among the generated fields. In order to discriminate between classical and quantum correlations we evaluate the quantum noise reduction, i.e. compare the fluctuations of the difference photocurrent between one mode and the sum of the other two with those coming from three uncorrelated coherent states. Preliminary results indicate that our scheme may achieve three-mode sub-shot noise correlations with current technology.

© EDP Sciences, Springer-Verlag 2008