冷原子系综内基于里德堡阻塞机制的单量子态制备与操控

发布时间：2018-07-12 16:02

本文选题：量子中继 + 量子存储　；参考：《中国科学技术大学》2017年博士论文

【摘要】：实现大尺度的量子通信和量子网络,是当前量子信息技术研究的核心内容之一,量子中继在其中起到至关重要的作用。冷原子系综是一个十分有希望用于构建量子中继系统的物理体系,然而其现有的实现方案具有不可避免的概率性缺陷。通过引入里德堡阻塞机制,我们能克服系综体系的概率性缺陷,实现确定性的单量子态制备与操控以及确定性的量子纠缠态制备,进而推动量子中继技术的快速发展。我们结合冷原子系综内基于概率源的传统量子存储、里德堡原子操控和里德堡阻塞效应等方面的研究成果,搭建了全新的里德堡冷原子系综量子信息处理实验平台,完成了一系列探索和研究工作。我们首先解决了至关重要的实验技术问题,如制备了微小原子系综,获得了窄线宽激光系统,等等。之后利用里德堡态电磁诱导透明机制,实现了里德堡态操纵,并观测到了里德堡强相互作用导致的非线性现象。进而在微小系综中,我们实现了里德堡阻塞和里德堡单激发态的相干操纵,确定性地制备了里德堡态和基态的集体激发态。进一步地,利用里德堡阻塞机制,我们在同一个冷原子系综中制备了两个基态集体激发态,并且利用受激拉曼跃迁实现了二者的Hong-Ou-Mandel干涉。该结果不仅为确定性制备光与冷原子系综纠缠奠定了基础,也是单系综多量子比特编码研究的实验开端。最后,我们利用两个集体激发态在里德堡阻塞机制下的动态演化、读出过程中的干涉效应,制备了极化自由度的光与原子纠缠。该方案的内禀效率为50%,这与以往概率性纠缠产生方案相比提升了两个数量级,将在量子中继系统中有重要应用。里德堡阻塞机制下的微小冷原子系综,结合了系综体系的集体增强优势和单粒子体系的确定性态制备及操控优势,在量子信息处理应用方面拥有广阔前景。我们相信,结合光晶格、腔增强技术的"里德堡型"量子中继器,是未来实现高效可用量子中继器的有力解决方案。
[Abstract]:The realization of large-scale quantum communication and quantum network is one of the core contents of quantum information technology, in which quantum relay plays an important role. Cold atomic ensemble is a promising physical system for constructing quantum relay systems. However, its existing implementation schemes have inevitable probabilistic defects. By introducing the Rydberg blocking mechanism, we can overcome the probabilistic defects of ensemble systems and realize the preparation and manipulation of deterministic single quantum states and deterministic quantum entangled states, thus promoting the rapid development of quantum relay technology. Based on the traditional quantum storage based on probabilistic source, Rydberg atomic manipulation and Rydberg blocking effect in cold atomic ensemble, we have built a new experimental platform for the processing of quantum information in cold atomic ensemble. A series of explorations and studies have been completed. We first solved some important experimental technical problems, such as the fabrication of micro atomic ensemble, the gain of narrow linewidth laser system, and so on. Then using the electromagnetic induced transparency mechanism of the Rydberg state, the Rydberg state manipulation is realized, and the nonlinear phenomena caused by the strong Rydberg interaction are observed. Furthermore, in the micro ensemble, we realize the coherent manipulation of the Rydberg blocking and the Rydberg single excited states, and prepare the collective excited states of the Rydberg state and the ground state in a deterministic way. Furthermore, by using the Rydberg blocking mechanism, we have prepared two ground state collective excited states in the same cold atomic ensemble, and we have realized the Hong-Ou-Mandel interference between them by the stimulated Raman transition. The results not only lay a foundation for the deterministic preparation of atomic ensemble entanglement, but also serve as the beginning of the research on single ensemble quantum bit coding. Finally, we make use of the dynamic evolution of two collective excited states under the Rydberg blocking mechanism and the interference effect in the readout process to prepare the polarized degree of freedom of light and atomic entanglement. The intrinsic efficiency of the proposed scheme is 50, which is two orders of magnitude higher than the previous probabilistic entanglement generation schemes, and will have important applications in quantum relay systems. The micro cold atomic ensemble based on the Rydberg blocking mechanism combines the collective enhancement advantage of the ensemble system with the deterministic state preparation and manipulation advantages of the single-particle system and has a broad prospect in quantum information processing applications. We believe that the "Rydberg" quantum repeater, which combines the optical lattice and cavity enhancement technology, is a powerful solution to the future realization of efficient and usable quantum repeaters.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：O413;O562

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