分类： 光学 >> 量子光学 提交时间： 2023-07-10
摘要： 原子系统有反射对称，有宇称，原子受激辐射，经平行平面谐振腔放大，可以产生宏观光子纠缠态[4]。 它是有确定宇称，总动量为零，确定能量，确定角动量的2N光子的量子纠缠态。观测它在时间、空间位置具有不确定性、随机性。根据海森堡测不准原理，其能量（频率）、动量完全确定。测量精度可以达到海森堡量子极限，具有量子2N增强效应（2N为纠缠光子数）。 通过实验测量它的几率分布P2N （t），以及它的傅里叶变换P2N （w-w0 ），实验结果与理论预期符合。并观测了宏观光子纠缠态的寿命，同样具有一个2N增强因子，实验结果与理论预期符合。
分类： 光学 >> 量子光学 提交时间： 2023-06-25
摘要： 多光子纠缠是量子通讯、光量子计算的核心技术。现在普遍使用的纠缠光源是自发参量下转换产生的两光子纠缠，虽已取得很大的成就，但离量子计算等的应用需求还很远，需要从理论和实验两个方面探索新路。 本文研究了受激辐射射基础过程，受激辐射的机理，发现此过程最初产生的两光子态的量子性质与受激辐射物质的对称性密切相关。如果受激辐射物质的电子态有宇称，它的波函数也有宇称，如原子、有对称中心的分子、有反演对称的晶体等，这类物质的电子态都有宇称和反射对称性。有宇称的物质的受激辐射过程遵守宇称守恒，受激辐射产生的两光子态有宇称，是迭加纠缠态。这样的两个纠缠光子经过平行平面谐振腔的作用，再通过受激辐射，不断重复这个过程，最终产生多光子纠缠。 本文主要结果和结论是：有宇称的物质的受激辐射产生多光子纠缠态。激光器物质的电子态如有宇称，则激光器谐振腔内（平行平面腔）的受激辐射产生的多光子态是纠缠态，并可从对称结构的双向单模激光器输出。 理论给出多光子纠缠的表示式。研制成一台对称结构双向输出单模He-Ne激光器，进行了多光子纠缠态的实验验证，实验结果与理论预期相符。
分类： 光学 >> 量子光学 提交时间： 2023-02-25
摘要： Optical focusing through scattering media has important implications for optical applications in medicine, communications, and detection. In recent years, many wavefront shaping methods have been successfully applied to the field, among which the population optimization algorithm has achieved remarkable results. However, the current population optimization algorithm has some drawbacks: 1. the offspring do not fully inherit the good genes from the parent. 2. more efforts are needed to tune the parameters. In this paper, we propose the mutate greedy algorithm. It combines greedy strategies and real-time feedback of mutation rates to generate offspring. In wavefront shaping, people can realize high enhancement and fast convergence without a parameter-tuning process.
分类： 光学 >> 量子光学 提交时间： 2023-02-25
Yaqing Jin
Ye Yang
Huibo Hong
Xiao Xiang
Runai Quan
Tao Liu
Ninghua Zhu
Ming Li
Ruifang Dong
Shougang Zhang
摘要： With energy-time entangled biphoton sources as the optical carrier and time-correlated single-photon detection for high-speed radio frequency (RF) signal recovery, the method of quantum microwave photonics (QMWP) has presented the unprecedented potential of nonlocal RF signal encoding and efficient RF signal distilling from the dispersion interference associated with ultrashort pulse carriers. In this letter, its capability in microwave signal processing and prospective superiority is further demonstrated. Both the QMWP RF phase shifting and transversal filtering functionality, which are the fundamental building blocks of microwave signal processing, are realized. Besides the perfect immunity to the dispersion-induced frequency fading effect associated with the broadband carrier in classical microwave photonics, a native two-dimensional parallel microwave signal processor is provided. These demonstrations fully prove the superiority of QMWP over classical MWP and open the door to new application fields of MWP involving encrypted processing.
分类： 光学 >> 量子光学 提交时间： 2023-02-25
摘要： Coherent interactions between quantum emitters in tailored photonic structures is a fundamental building block for future quantum technologies, but remains challenging to observe in complex solid-state environments, where the role of decoherence must be considered. Here, we investigate the optical interaction between two quantum emitters mediated by one-dimensional waveguides in a realistic solid-state environment, focusing on the creation, population and detection of a sub-radiant state, in the presence of dephasing. We show that as dephasing increases, the signatures of sub-radiance quickly vanish in intensity measurements yet remain pronounced in photon correlation measurements, particularly when the two emitters are pumped separately so as to populate the sub-radiant state efficiently. The applied Green's tensor approach is used to model a photonic crystal waveguide, including the dependence on the spatial position of the integrated emitter. The work lays out a route to the experimental realization of sub-radiant states in nanophotonic waveguides containing solid-state emitters.
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