Stephen Walborn

Universidad Federal de Rio de Janeiro

Jueves 15/9/2011, 14 hs
Aula Federman, 1er piso, Pabellón I 

The spatial correlations of photon pairs produced by spontaneous parametric down-conversion have been studied for nearly forty years. They appear simultaneously in the complementary near- and far-field transverse variables of the photons. It has been shown that these correlations are quantum-mechanical in nature, and give rise to a number of non-classical effects that could be exploited for improved imaging and metrology, as well as more secure communications. In this seminar I will discuss two recent experiments that illustrate several novel non-local aspects of spatial correlations. The first shows that appropriately engineered photons violate a non-locality witness based on entropy functions, which shows that the correlations cannot be described by a local "classical" model. In the second experiment, an analog of an optical vortex, such as that which appears in a classical optical beam with non-zero orbital angular momentum, is observed in a non-local coordinate plane. In this sense the optical vortex appears in the correlations of the photon pairs.