基于热原子系统产生连续变量多组分纠缠光源的实验研究

Continuous variable multipartite entangled light sources are essential in realizing quantum communication and quantum internet. Atomic system could not only be a good candicate for generating entangled light beams, but also shows great ability in storage of quantum states. Besides, it has been verified to be capable of creating entangled images, which makes it possilbe to create images of much higher quality. So it is of great value in the transmission and storage of quantum information by using multipartite etangled light beams whose wavelength matches the atomic transition. Our project maily focuses on experimental generation of continuous variable multipartite entangled light beams through the nonlinear parametric amplification process in hot rubidium vapor. Combining two counter-propagating pump beams to interact with the atoms to fulfill quadripartite entanglement by measuring the quadrature amplitude and quadrature phase of the four newly obtained beams with homodyne detection, looking for the dependence of the entanglement on some of the physical parameters and finding the agreement between the experiment results and the theory. We will also seed the vapor cell with two spatially modulated probe beams which are phase matching to the pump beams, therefore we could have two pairs of bright probe and conjugate beams, and the four beams are supposed to be four images with strong quantum correlation.

连续变量多组分纠缠光源，是实现量子通信、构建量子网络的重要元素，而利用原子系统不仅能产生连续变量量子光源，也可以对量子态实现存储，同时还能实现量子纠缠成像，有效的提高图像的成像质量。因此，制备基于原子跃迁波段的多组分纠缠光源，对量子信息的传输、存储具有重要的应用价值，为当前的研究热点之一。本项目研究重点是实验上利用光在热的铷原子蒸气中的非线性参量放大过程，产生连续变量多组分纠缠光源。通过反向共线的强泵浦光激发原子气体获得四束连续光场，利用平衡零差探测法研究四光的正交振幅和正交位相的纠缠特性，并探索纠缠强度对物理环境的依赖关系，验证相关理论结果；其次通过对参量放大过程注入两束种子光，获得两对明亮的探针光和共轭光，并对种子光做空间光调制形成多模图像，研究经过参量放大得到四个图像之间的纠缠特性，

主要研究以热的铷原子气体中的四波混频过程产生强度差噪声压缩光源、实现多光束的量子纠缠以及量子成像、研究图像的量子关联度对四波混频增益的空间分布关系，探索一种增强量子纠缠的实验方法和技术。研究目标旨在为量子纠缠网络的建立提供潜在的连续变量多组分纠缠光源，促进连续变量纠缠态在量子信息科学中的应用。我们从实验上已经证明能够获得高质量的强度差压缩光源，并产生明亮的量子纠缠图像。我们研究了四波混频过程中probe光的增益对纠缠图像质量的影响，得到了数值模拟结果及相应的实验比较。另外，项目资助下，我们在理论上也做了一定的基于量子纠缠方面的理论工作。包括：光子数扣除压缩真空相干叠加的量子纠缠问题的研究、多光子催化下的纠缠相干态的纠缠度提高的研究、通过连续变量ERP量子纠缠的三体压缩纠缠态的隐形传输研究、在实际环境中通过三个可调谐变量来研究连续变量隐形传输中的最优保真度问题，以及其他的相关研究工作，都得到了本项目基金的资助。相关研究成果发表在 Front. Phys., Phys.Rev. A, Laser Phys. Lett., Int. J. Theor. Phys 等SCI学术期刊上。