微弱光信号的量子增强接收优化方法(特邀)  

Optimization of quantum-enhanced receiving methodfor weak optical signal(invited)

作　　者：东晨 郭畅 吴田宜 冉阳 党可征 李福全 周子超 Dong Chen;Guo Chang;Wu Tianyi;Ran Yang;Dang Kezheng;Li Fuquan;Zhou Zichao(Institute of Information and Communication,National University of Defense Technology,Wuhan 430033,China)

机构地区：[1]国防科技大学信息通信学院,湖北武汉430033

出　　处：《红外与激光工程》2023年第6期132-141,共10页Infrared and Laser Engineering

基　　金：国防科技大学自主创新科学基金项目(22-ZZCX-036)。

摘　　要：在经典理论框架下,相干探测性能受限于散粒噪声对应的标准量子极限,而量子增强接收技术通过引入位移算子,采用关联的方式将经典的平衡零拍/零差探测转化为光子数态的测量,理论上可以突破标准量子极限并不断逼近Helstrom极限。无歧义量子态识别(Unambiguous State Discrimination,USD)是量子增强接收常用的识别判决策略之一。然而,由于微弱光信号的能量有限,传统的USD量子增强接收方法的适用微弱信号范围较小,微弱信号识别的错误率较高。提出了一种QPSK调制量子增强接收的混合测量优化方案,该方案首先通过二态零差测量将QPSK相干态的区分转化为BPSK相干态的区分,然后通过BPSK量子增强接收测量实现相干态的无歧义识别。仿真表明,混合测量方案在平均光子数在3.2~11.3之间优于经典的外差测量方案,而且比传统QPSK量子增强接收方案具有更大的适用信号范围。Under the framework of classical theory,the performance of coherence detection is limited by the standard quantum limit(SQL)corresponding to the shot noise.However,the quantum-enhanced receiving technology can break the SQL and approach the Helstrom limit by introducing the displacement operation and converting the classical measurement into the measurement of photon number states.Unambiguous state discrimination(USD)is one of the commonly used discrimination strategies for quantum-enhanced reception.However,due to the limited energy of weak signals,the traditional USD quantum-enhanced receiving method has a high error rate of weak signal recognition.A hybrid measurement scheme for quadrature phase-shift-keying(QPSK)coherent states is developed.The scheme firstly converts the discrimination of QPSK coherent states into the distinction of BPSK coherent states by homodyne detector(HD),and then realizes the unambiguous discrimination of coherent states by BPSK quantum-enhanced receiving measurement.The simulation results show that the hybrid scheme is superior to the classical measurement scheme in the average photon number between 3.2 and 11.3,and has a larger signal range than the traditional QPSK quantum-enhanced receiving scheme.Objective Coherent states are a critical carrier in optic communication and quantum information processing due to their intrinsic resilience to the loss of coherence.Unambiguous state discrimination(USD),which aims to realize the error-free discrimination of coherent states by outputting"no result"for the finite ambiguous results,is especially essential in quantum key distribution and quantum digital signatures.Recently,Becerra first experimentally demonstrated a generalized quantum measurement for USD of four non-orthogonal coherent states with a displacement operator and single-photon detector(SPD).As the unambiguously correct probability is still significantly low,Ref.introduces an adaptive feedback strategy and presents an adaptive generalized measurement scheme for USD of QPSK coher

关 键 词：量子增强接收 混合测量方案 无歧义量子态识别 自适应反馈 

分 类 号：TN929.1[电子电信—通信与信息系统]