Coherent control of entangled states of atomic ensembles

The realization of quantum communication protocols over a scalable quantum network depends on precise control of entangled states. Recent experimental progress toward a scalable quantum network has included the demonstration of heralded entanglement creation and the distribution of entanglement amongst the nodes of a network. In our system quantum nodes are realized with a pair of atomic ensembles of laser cooled Cs atoms. We will discuss recent developments including the storage and retrieval of entanglement into and out of a quantum memory [1] and an investigation of the processes by which entanglement decays in our system [2]. [1] K. S. Choi, H. Deng, J. Laurat, and H. J. Kimble, arXiv:0712.3571v2 (2008). [2] J. Laurat, K. S. Choi, H. Deng, C.-W. Chou, and H. J. Kimble, Phys. Rev. Lett. \textbf{99}, 180504 (2007).