  We experimentally demonstrate a new measurement scheme for the discrimination
of two coherent states. The measurement scheme is based on a displacement
operation followed by a photon number resolving detector, and we show that it
outperforms the standard homodyne detector which we, in addition, proof to be
optimal within all Gaussian operations including conditional dynamics. We also
show that the non-Gaussian detector is superior to the homodyne detector in a
continuous variable quantum key distribution scheme.
