Quantum Entanglement Among Multiple Memories for Continuous Variables

Quantum network is constituted by quantum channels and quantum nodes. The interaction between non-classical optical modes and quantum nodes, as well as quantum entanglement among multiple distant quantum nodes are the building blocks of quantum network, which enable to achieve a plethora of quantum information protocols, such as distributed quantum computation, quantum state transfer across quantum nodes, and quantum clock network. On one hand, the multipartite non-classical states of optical modes, which can directly interact with atomic ensembles, are required for the practical applications of quantum network. On the other hand, a crucial goal of quantum network is to unconditionally generate and on-demand store and retrieve multipartite entangled states in atomic ensembles. This paper presents an up-to-date review on recent developments in these areas: multipartite continuous-variable polarization entangled optical modes have been created by transforming quantum state from quadrature into polarization components; and a scalable quantum network with deterministic entanglement among multiple quantum memories has been constructed by transferring spatially separated entangled optical modes into atomic ensembles.