基于有限尺寸冷原子系综的量子纠缠特性研究

The continuous variable entangled states prepared in cold atomic ensembles have the broad application prospect for realization of quantum teleportation, quantum dense coding and quantum computation,because the atomic ensembles have the advantages of being easily manipulated and achieving strong collectively enhanced couplings. In the existing research results it is mostly taken the thermodynamic limit of infinite number of atoms in the atomic ensemble. However, in fact the number of atoms in an atomic ensemble is finite. The project will firstly consider the finite-size of cold atomic ensembles, further study the quantum entanglement characteristics from the interaction of finite-size atomic ensembles with degenerate counter-propagating field modes of optical cavity, and fully explore essence of finite size effect and a wide variety of unusual features. To be specific:(1)study the quantum entanglement properties of finite-size cold atomic ensembles in the ring optical cavity;(2)analyze the quantum entanglement properties of finite-size cold atomic ensembles in the array of cavities;(3)disscuss the quantum entanglement properties of finite-size cold atomic ensembles in nanomechanical cavity. We also propose novel schemes to prepare multimode entangled state based on the cold atomic ensembles,which will provide a theoretical basis for the application and development of quantum information processing and quantum network.

由于冷原子系综具有易操纵和集体增强等优点，因而利用冷原子系综制备的连续变量纠缠态在量子态的隐形传输、量子密集编码、量子计算等方面具有广阔的应用前景。在已有的研究成果中大多假设冷原子系综足够大，而实际上冷原子系综中的原子数目是有限的。因此本项目针对有限尺寸冷原子系综，在不采取热力学极限近似的情况下，深入研究冷原子系综在光腔中同向和反向拉曼双光子激发的共同作用下产生的量子纠缠特性，并全面探索有限尺寸效应的实质及其带来的新现象。拟从以下三个方面开展研究：（1）多个有限尺寸冷原子系综在环行光腔中产生的量子纠缠特性；(2)有限尺寸冷原子系综在光腔耦合阵列中产生的量子纠缠特性；（3）有限尺寸冷原子系综在光学机械体系中产生的量子纠缠特性。我们将从中提出基于冷原子系综制备多模连续变量纠缠态的新方案，有望为量子信息处理和量子网络的应用及发展提供理论依据。

基于当前光腔中原子系综的理论与实验研究状况，本项目深入讨论了原子系综在环行光腔中产生的量子纠缠特性；原子系综在光腔耦合阵列中产生的量子纠缠特性；原子系综在光学机械体系中产生的量子纠缠特性，并提出了多种基于原子系综制备多模连续变量纠缠态的新方案。除此以外，我们还研究了光力腔系统中机械振子的量子冷却，有望为量子信息处理和量子网络的应用及发展提供理论依据。