A robust hybrid receiver for binary phase-shift keying discrimination in the presence of phase noise

Abstract: We address the problem of coherent state discrimination in the presence of phase diffusion. We investigate the role of the hybrid near-optimum receiver (HYNORE) we proposed in [J. Opt. Soc. Am. B 40, 705-714 (2023)] in the task of mitigating the noise impact. We prove the HYNORE to be a robust receiver, outperforming the displacement photon-number-resolving (DPNR) receiver and beating the standard quantum limit in particular regimes. We introduce the maximum tolerable phase noise $\sigma_{\mathrm{max}}$ as a figure of merit for the receiver robustness and show that HYNORE increases its value with respect to the DPNR receiver.