We report on a test of Bell inequalities using a non-maximally entangled
state, which represents an important step in the direction of eliminating the
detection loophole. The experiment is based on the creation of a polarisation
entangled state via the superposition, by use of an appropriate optics, of the
spontaneous fluorescence emitted by two non-linear crystals driven by the same
pumping laser. The alignment has profitably taken advantage from the use of an
optical amplifier scheme, where a solid state laser is injected into the
crystals together with the pumping laser. In principle a very high total
quantum efficiency can be reached using this configuration and thus the final
version of this experiment can lead to a resolution of the detection loophole,
we carefully discuss the conditions which must be satisfied for reaching this
result.Comment: to be published in Proc. of International Workshop on Optics and
Spectroscopy (Hanoi, Vietnam
