  We propose and experimentally demonstrate a near-optimal discrimination
scheme for the quadrature phase shift keying protocol (QPSK). We show in theory
that the performance of our hybrid scheme is superior to the standard scheme -
heterodyne detection - for all signal amplitudes and underpin the predictions
with our experimental results. Furthermore, our scheme provides the hitherto
best performance in the domain of highly attenuated signals. The discrimination
is composed of a quadrature measurement, a conditional displacement and a
threshold detector.
