利用原子系综中的量子记忆进行非经典关联光子对产生的实验研究

项目名称： 利用原子系综中的量子记忆进行非经典关联光子对产生的实验研究

项目编号： No.10874106

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 电工技术

项目作者： 王海

作者单位： 山西大学

项目金额： 50万元

中文摘要： 通过光与原子相互作用在原子系综中产生量子记忆是进行量子通讯的重要手段，最近该研究方向受到了极大的关注。本项目主要内容是开展原子系综中量子记忆产生、操控及非经典关联光子对产生的实验研究。拟通过Raman(拉曼)散射产生Stokes光子，并建立原子记忆，再通过EIT读出原子记忆，释放出信号光子，通过符合计数方法测量它们之间的关联特性。在弱磁场条件下，研究不同Zeeman子能级的原子Larmor进动对自旋相干性寿命的影响；将信号光子的左、右旋圆偏振分量分离，测量其左旋和右旋圆偏振分量间的非经典关联特性。在项目实施过程中，我们使用冷原子作EIT介质。进行了Raman过程产生量子关联光子的实验研究。在弱磁场（沿控制光方向）条件下，研究了原子Larmor进动对自旋相干性寿命的影响。通过改变两读出光的相对位相消除了恢复信号的振荡变化。使用1/4波片和偏振棱镜分离了读出信号光子的左旋和右旋圆偏振分量，发现当磁场方向确定时,信号光的"左""右"通道没有能量交换。使用Raman(拉曼)双光子跃迁实现了自旋波矢量在Bloch球上旋转的操控。本项目的研究将为操控基于原子系综的量子记忆提供基础。

中文关键词： 量子记忆;电磁感应透明;非经典关联;自旋相干性;原子系综

英文摘要： The quantum memory in atomic ensembles generated by the interaction between atoms and light is important tools for the quantum information processing, which is pay more attention in the recent years.The presented project focus on the experimental studies on the generation of quantum memory, the manipulation of it and the generation of nonclassical photons. We will generate the stokes photons by Raman scattering and then build the quantum memory. By using EIT processing, we then retrieve the signal photons stored in the atomic ensemble. We will measure correlations between them. Under the condition of the weak magnetic field, we will study the effect of atomic Larmor precessing of the different Zeeman coherences on the spin-wave lifetime. We will also separate the left- and right-circularly-polarized components and measure their correlation characters. In the implementation of the project, we use the cold atoms as EIT medium. We carried out the experimental studies on the quantum correlation of photon pairs.Under the condition of the weak magnetic field (whose direction is along at the direction of the light propagation) , we have studied the effect of atomic Larmor precessing of the atomic spin-wave lifetime.By varying the relative phase between the two reading beams, we eliminated the oscillation of the retrieval signal light. By using 1/4 wave-plates and polarized beam splitters, we separated the left- and right-circularly polarized components of the retrieval signal light, we find that there is almost no energy exchange between the "left" and "right" channels when the direction of the magnetic field can be well defined. The spin-wave vector is rotated on the Bloch sphere by using Raman two-photon manipulation. The presented works will provide help for the manipulation of the quantum memory based on atomic ensemble.

英文关键词： quantum memory; Electromagnetically induced transparency; nonclassical correlation; spin coherence; atomic ensemble