Theory of the light - atomic ensemble interface

提出了光与冷光厚原子系综相互作用的理论研究方案。对光场和原子物质之间界面的量子控制对于未来可扩展的量子网络系统是至关重要的，它将应用于远程各方之间的信息安全共享。在这种情况下，原子系综的成功实施取决于它们与光输入和输出通道的相互作用实现高效和持久的一致性。利用原子物理和量子光学的分析和数值方法，对这种多模多原子系统中的相互作用的性质和特征进行了深入的研究。系综中光场与多原子态相互作用的集体增强为理解它们提供了组织原则，也为光与物质之间的强定向耦合提供了机制。光在光学厚介质中传播的另一个特征，即被称为暗态极化的光/多原子混合激发，将被作为一种实现光脉冲的受控存储和随后的恢复的手段而被研究到单光子水平。这项研究将集中在现实的实验场景中，包括研究原子系综制备的相关状态，以及入射光场。在这种情况下，环境磁场与原子核和电子的自旋的耦合提供了主要的退相干机制。这一过程及其对光场整体存储和回收效率的影响将被详细研究。

A program of theoretical research on the interaction of light with cold, opticallythick, atomic ensembles is proposed. Quantum control of the interface between lightfields and atomic matter is essential for future scalable quantum network systems whichhave application to the secure sharing of information between remote parties. The successof the implementation of atomic ensembles in that context depends on achieving highefficiency and long-lived coherence in their interaction with the light input and outputchannels. The properties and characteristics of the interactions in such a multi-mode andmulti-atom system will be thoroughly addressed by means of the analytical and numericalmethods of atomic physics and quantum optics. The collective enhancement of theinteractions between the light field and multi-atom states of the ensemble provides anorganizing principle for their understanding, as well as a mechanism for strong,directional coupling between light and matter. Another characteristic of light propagationin optically thick media, the mixed light/multi-atom excitation known as the dark statepolariton, will be investigated as a means to perform controlled storage, and subsequentretrieval, of light pulses down to the single photon level. The research will focus onrealistic experimental scenarios including the study of relevant states of preparation of theatomic ensemble, and the incident light fields. In this context, the coupling of ambientmagnetic fields to the spins of the atomic nucleus and electrons provides the primarydecoherence mechanism. This process and its impact on the overall storage and retrievalefficiency of the light field will be investigated in detail.