Quantum-Limited Symbol-Blind Channel Estimation for Coherent State Discrimination

2026/07/27 by Hongxu Chen, Renzhi Yuan, Haifeng Yao +1
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Abstract

Residual dispersion breaks temporal-mode matching in photon-starved coherent links. For equiprobable M-ary PSK coherent states in a known spectral mode, with unknown symbols and carrier phase, we establish the quantum limit for blind joint estimation of group delay and second-order dispersion: after eliminating the common phase, it is 4N_sC, set by the covariance of the centered generators alone. A multi-output quantum pulse gate with photon-number-resolving detection locally attains it and supports reception below the standard quantum limit under turbulent fading.

Citations

• Multi-Stage CD-Kennedy Receiver for QPSK Modulated CV-QKD in Turbulent Channels
• Optimally Displaced Threshold Detection for Discriminating Binary Coherent States Using Imperfect Devices
• One photon-per-bit receiver using near-noiseless phase-sensitive amplification
• Gaussian quantum information

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