16-QAM Quantum Receiver with Hybrid Structure Outperforming the Standard Quantum Limit

¹ Department of Electronic Engineering and Information Science, University of Science and Technology of China, 230027 Hefei, China
² Key Laboratory of Electromagnetic Space Information, Chinese Academy of Sciences, 230027 Hefei, China
³ Nanjing Research Institute of Electronic Technology, 210013 Nanjing, China

^a Corresponding author: zbing@ustc.edu.cn

Abstract

Quantum receivers which can discriminate phase shift keying (PSK) and pulse position modulation (PPM) signals below the standard quantum limit have been proposed and some have been demonstrated experimentally. But for quadrature amplitude modulation (QAM) signals, few literatures have been reported so far. It is important to reduce the average error probability of QAM signals below the standard quantum limit (SQL), since these modulation have a high spectral efficiency. In this paper, we present a quantum receiver for 16-QAM signals discrimination with hybrid structure, which contains a homodyne receiver and a displacement receiver. By numerical simulation, we prove that the performance of the quantum receiver can outperform the SQL, and it can be improved by an optimized displacement.