[Todos] Coloquios del Departamento de Física (jueves 15/9)

[pdmitruk en df.uba.ar]

   COLOQUIOS DEL DEPARTAMENTO DE FÍSICA FCEyN - UBA

                              http://coloquios.df.uba.ar/

                              Charla, café y galletitas
                En el Aula Federman, 1er piso, Pabellón I,
                                Ciudad Universitaria

                            Jueves 15 de septiembre, 14hs,

  NON-LOCAL EFFECTS OF SPATIALLY CORRELATED PHOTONS

                                   Stephen Walborn

                    Universidad Federal de Rio de Janeiro

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?ll 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.
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