Discrimination of binary coherent states using a homodyne detector and a photon number resolving detector

TL;DR

This paper compares probabilistic quantum measurement strategies using homodyne and photon number resolving detectors to improve discrimination of binary coherent states, demonstrating the superior performance of the PNR receiver.

Contribution

The study introduces and experimentally demonstrates a photon number resolving receiver that outperforms homodyne-based strategies in quantum state discrimination.

Findings

PNR receiver surpasses homodyne receiver in error probability

PNR measurement is experimentally feasible and effective

Homodyne receiver with postselection is optimal among Gaussian operations

Abstract

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