We present a proposal for storing and retrieving a continuous-variable quadripartite polarization-entangled cluster state, using macroscopic atomic ensembles in a magnetic field. The Larmor precession of the atomic spins leads to a symmetry between the atomic canonical operators. In this scheme, each of the four spatially separated pulses passes twice through the respective ensemble in order to map the polarization-entangled cluster state onto the long-lived atomic ensembles. The stored state can then be retrieved by another four read-out pulses, each crossing the respective ensemble twice. By calculating the variances, we analyzed the fidelities of the storage and retrieval, and our scheme is feasible under realistic experimental conditions.
@article{arxiv.1105.4814,
title = {Storage and retrieval of continuous-variable polarization-entangled cluster states in atomic ensembles},
author = {Da-Chuang Li and Chun-Hua Yuan and Zhuo-Liang Cao and Weiping Zhang},
journal= {arXiv preprint arXiv:1105.4814},
year = {2015}
}