We investigate quantum measurement strategies capable of discriminating twocoherent states probabilistically with significantly smaller errorprobabilities than can be obtained using non- probabilistic statediscrimination. We apply a postselection strategy to the measurement data of ahomodyne detector as well as a photon number resolving detector in order tolower the error probability. We compare the two different receivers with anoptimal intermediate measurement scheme where the error rate is minimized for afixed rate of inconclusive results. The photon number resolving (PNR) receiveris experimentally demonstrated and compared to an experimental realization of ahomodyne receiver with postselection. In the comparison it becomes clear, thatthe perfromance of the new PNR receiver surpasses the performance of thehomodyne receiver, which we proof to be optimal within any Gaussian operationsand conditional dynamics.
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