摘要
量子增强接收技术具有比传统的相干探测技术更高的测量性能极限,在相干光通信领域能够为非正交量子态的识别提供更低的误符号率,提升相干光通信系统的性能。然而,目前QPSK信号的量子增强接收自适应反馈方案仍然面临方案过于复杂或性能难以突破标准量子极限的问题。本文联合经典零差测量和量子测量设计了混合测量方案,并基于报道的实验数据优化方案参数,最后通过蒙特卡罗仿真和数值模拟,计算混合测量方案在实验参数环境下的性能。该方案通过零差测量实现QPSK四态识别到二态识别问题的转换,并通过二元量子测量实现最终判决。仿真结果说明:对于平均光子数小于2的微弱相干光信号,混合测量方案具有在实际条件下突破标准量子极限的能力,在平均光子数为2时,误符号率相比标准量子极限降低了10%。本研究为QPSK微弱信号的量子增强接收提供了一种结构简单、性能能够突破标准量子极限的方案,为量子增强接收技术在星地相干光等长距离通信系统的应用提供了参考。
Objective Coherent states are important information carriers in the field of communication and are widely used in star-ground coherent optical communication and star-ground quantum key distribution scenarios. Improving the discrimination accuracy for coherent states is a key method for achieving longer communication distances. The quantum-enhanced measurement technique can overcome the limitations of shoot noise and the standard quantum limit(SQL), allowing increased communication distance of starground optical communication systems. Researchers have conducted a series of studies on quantum-enhanced measurements and proposed various schemes including adaptive feedback strategies and optimization of displacement operators. Although the SQL is surpassed in quantum-enhanced measurement schemes that use adaptive feedback strategies, the experimental structures of these schemes are usually complex. Therefore, designing such a scheme with a simple structure and good performance for weak signals remains an unresolved research problem. We hope to construct a measurement scheme for weak coherent states with a simple experimental structure that can surpass the SQL.Methods To determine weak coherent states, this paper proposes a new hybrid measurement scheme based on homodyne and binary quantum measurements, as depicted in Fig. 1. The scheme includes two successive measurements of the coherent states: the first involves a homodyne detector, which can preliminarily determine the received coherent states. The results of the first measurement are then provided as feedback for the second stage. Subsequently, the second measurement stage involves a binary quantum measurement with two partitions, which discriminates the signal states. The received coherent state is first divided using a beam splitter(BS) with transmittance T and reflectivity R. The transmitted and reflected parts of the received signal state are output to the quantum measurement and HD stages, respectively. T and R can be varied to adjust the signal amplitude for
作者
郭畅
党可征
吴田宜
杨君刚
冉阳
周子超
东晨
Guo Chang;Dang Kezheng;Wu Tianyi;Yang Jungang;Ran Yang;Zhou Zichao;Dong Chen(College of Information and Communication,National University of Defense Technology,Wuhan 430033,Hubei,China)
出处
《中国激光》
EI
CAS
CSCD
北大核心
2024年第14期247-254,共8页
Chinese Journal of Lasers
基金
国防科技大学自主创新科学基金项目(22-ZZCX-036)。
关键词
量子测量
标准量子极限
零差测量
QPSK相干态
quantum measurement
standard quantum limit
homodyne measurement
QPSK coherent state
