基于原子非线性的全光量子器件及其特性的研究

As a kind of quantum coherent devices, all-optical quantum device produced by the nonlinear interaction of atoms and light in light- matter coupled system, can be used to control the coherent transmission of the photons in the constrained system and photonic network, not only has the traditional optics feature such as optical isolator, light mirror, etc., but also exhibit the physical characteristics like diode, transistor, and other electronic component. The biggest difference with traditional devices is that all-optical devices can be easily coupled to the quantum information processing systems, to achieve all-optical manipulation of quantum states, which promote the development of quantum information technology to the practical direction of integration and networking. On th basis of our experimental research about atomic coherence and four wave mixing effects ,this project is mainly researching the all-optical devices and their characteristics based on atomic gas, and the primarily method is through optical refractive index modulation induced by atomic coherence in the cesium atomic system coupled by the bicromatic fields. Our research contents are as follows:1) In the EIT medium, the experimental research of optical device effects such as optical diode, optical transistor and mirror, and so on; 2), The experimental research and theoretical analysis of the operating characteristics of the optical devices with the variation of the nonlinear effects; 3), The experimental research of multi-channel all-optical signal field control and quantum information conversion by means of optical devices applied to the four-wave mixing process; 4) Experimental studies and theoretical analysis of the quantum noise characteristics of the signal field controlled by all-optical. Through this project, we will explore the feasible ways to realize the quantum network technology, such as multi-channel all optical switching, multi-channel quantum storage and conversion and quantum logic gates,etc. And furthermore, it will deepen peoples' understanding about four wave mixing due to atomic coherent effect.

全光量子器件是一种量子相干器件，它可用于控制光子在受限系统和光子网络中的相干传输，实现对各种量子态的全光操控，它已成为目前快速发展的重要领域之一，推动了量子信息技术向集成化和网络化的实用型方向发展。本项目拟在已有的原子相干和四波混频效应的实验研究基础上，在双色场耦合的铯原子系统中，利用原子相干对光折射率的调制，开展基于原子气体的全光器件及其特性的研究。具体内容包括：1)、在EIT介质中，实现光学二极管、三极管及反射镜等光学器件效应的实验研究；2）、实验研究和理论分析光学器件工作特性随介质非线性效应变化规律；3）、光学器件应用到四波混频过程，对多通道信号场的全光控制及量子信息转换的实验研究；4）、全光控制信号场的量子噪声特性的实验研究及理论分析。探索多通道量子信息存储、量子逻辑门等量子网络技术的可行性方案。

全光量子器件是当前量子通讯领域一个非常热门的研究课题，其本质就是通过对相互作用光子的相干控制，从而实现对各种量子态的全光操控.而碱金属原子具有相对稳定的物理特性，是构成全光量子器件的重要组成单元，可以很好的作为未来量子信息存储和交换的有效媒介。因此我们在已积累的原子相干和四波混频效应的实验研究基础上，利用铯原子作为研究对象，在全光控制的光学反射镜、光学二极管效应，以及具有强度关联的纠缠光源制备以及基于原子-腔耦合系统下的光传输特性等方面开展了相关研究。首先，我们基于双lambda型原子系统，研究了通过受激拉曼的的四波混频过程，实验上获得一对频差约18.4GHz、强度差压缩约2.5dB的量子关联光场，理论上定性的分析了在较大基态超精细分裂能级条件下能产生量子关联的最佳物理条件，为下一步开展基于原子吸收线附近的级联多组分纠缠光场的产生及高阶模关联光场的制备奠定了理论和实验基础；其次，通过驻波耦合场作用的原子系统，基于反常色散补偿相位失配理论，实验验证了反射效率在不同能级条件下，随光场之间的角度及频率失谐等参量的变化规律，实验获得反射效率超过60%的反射信号，实现了具有滤膜降噪功能的光控反射镜，并将部分功能集成化和仪器化；第三，理论分析比实验研究了耦合光的光泵浦效应对热原子介质的极化特性的影响，发现光泵浦导致介质的强吸收效应与作用光场的方向无关，而取决于泵浦光的拉比频率及失谐程度，该结论对于基于原子-腔耦合系统下的量子行为的研究具有非常重要的指导意义。综上所述，该项目的研究成果丰富了基于原子相干的四波混频效应的研究内容，推动了全光控制的多通道量子通讯、量子逻辑门操控、量子计算等量子信息技术向集成化和网络化的实用型方向发展。