【作者】 李娟；

【导师】 刘奎；

【作者基本信息】 山西大学 ， 光学， 2019， 硕士

【摘要】 连续变量量子纠缠作为量子光学的重要资源之一,具有经典光场不具有的量子关联特性。通过对其不断的研究,连续变量量子纠缠已经被广泛应用到多个领域,如量子通讯,量子计量和量子计算等方面。光场的空间模式,如厄米高斯模和拉盖尔模,具有复杂的空间分布。因此将这种空间模式与量子纠缠相结合的空间多模纠缠态引起了物理学家们浓厚的研究兴趣。利用这种空间多模纠缠态作为量子信道可以实现信息的并行传输和处理,提高信道容量和量子计算速度。此外,还可将这种多模纠缠态应用在超分辨量子成像领域来提高图像成像质量,以及在量子精密测量领域中提高位移倾角等空间物理量的测量精度,具有重要的应用价值。本文主要围绕基于泵浦空间操控实现连续变量多模纠缠态的纠缠增强的相关理论和实验来展开,其主要内容包含以下几个方面:1.理论上分析了超纠缠态产生过程中泵浦场与下转换场间的模式依赖关系,得出了在不同泵浦空间分布下,纠缠不可分度随泵浦功率变化的理论曲线,发现了产生超纠缠态的最佳泵浦模式为L G₀⁰和L G₁⁰的叠加模式,实验上为了便于制备,使用L G₁⁰模做泵浦场来产生高质量的纠缠输出。此外我们还设计了空间多模光学参量振荡器,并测量了L G₀⁰和LG₁⁰模两种不同泵浦模式下的纠缠,其中使用L G₁⁰模做泵浦场时获得了更高质量的既有偏振纠缠又有轨道角动量纠缠的连续变量超纠缠,这种超纠缠态可以用于超密集编码以及高维量子通讯等方面。2.在理论上分析了如何利用单个多模共振的光学参量放大器制备空间四组份cluser态,在实验上进行了验证与测量,并通过优化的泵浦模式提高了cluser态的纠缠度。相比利用多束压缩态在分束镜网络上耦合制备多组份纠缠态,该方装置更为简单。更多还原

【Abstract】 Continuous variable quantum entanglement is one of the important resources in quantum optics.It has the quantum correlation property that classical light field does not have.And now It has been widely used in many fields,such as quantum communication,quantum metrology and quantum computing.The spatial modes of the light field,such as the Hermite mode and the Laguerre mode,have a complex spatial distribution.Therefore,the continuous variable multimode entangled state based on this spatial mode has attracted a lot of research interest.By using this spatial multimode entangled state as a quantum channel,parallel transmission and processing of information can be realized,and channel capacity and quantum computing speed can be improved.In addition,this multimode entangled state can be applied to the field of super-resolution quantum imaging to improve the image imaging quality,as well as the measurement accuracy in the field of quantum precision measurement such as displacement tilt angle.It has important application value.In this thesis,we theoretically and experimentally study entangle enhancement of continuous variables multimode entanglement based on pump space manipulation.The main contents are as follows:1、we theoretically analyzed the relationship of the pump and the two down-conversion modes and the effect of different pump modes on the inseparability.And we find that the optimal pump mode is the superposition ofLG₀⁰ andLG₁⁰ mode.However,the optimal pump mode is rather complicated and difficult to experimentally generate,the alternative scheme is using LG₁⁰ mode as the pump field to obtain the optimal entanglement.In the experiment,the LG₀⁰ mode or LG₁⁰ mode was used as the pump field to drive the non-degenerate optical parametric amplifier operating in spatial multimode.Then the hyperentanglement in orbital angular momentum and spin angular momentum was produced.The experimental results show that the enhancement for the inseparability of orbital angular momentum and spin angular momentum entanglement respectively was achieved usingLG₁⁰ mode.2、We theoretically analyzed how to produce quadripartite cluster states using a single multimode resonant optical parametric amplifier.Experimentally we also verify and measure for four-partite cluster states.In addition,the entanglement of the cluster states is improved by optimizing the pump mode.Compared with the preparation of multipartite entanglement by coupling the several squeezed state light field in the beam splitting,this device is more concise.更多还原