Storage and retrieval of continuous-variable polarization-entangled cluster states in atomic ensembles

摘要

We present a proposal for storing and retrieving a continuous-variablequadripartite polarization-entangled cluster state, using macroscopic atomicensembles in a magnetic field. The Larmor precession of the atomic spins leadsto a symmetry between the atomic canonical operators. In this scheme, each ofthe four spatially separated pulses passes twice through the respectiveensemble in order to map the polarization-entangled cluster state onto thelong-lived atomic ensembles. The stored state can then be retrieved by anotherfour read-out pulses, each crossing the respective ensemble twice. Bycalculating the variances, we analyzed the fidelities of the storage andretrieval, and our scheme is feasible under realistic experimental conditions.