Coherent and reversible storage of multi-photon entanglement with a multimode quantum memory is essential for scalable all-optical quantum information processing. Although single photon has been successfully stored in different quantum systems, storage of multi-photon entanglement remains challenging because of the critical requirement for coherent control of photonic entanglement source, multimode quantum memory, and quantum interface between them. Here we demonstrate a coherent and reversible storage of biphoton Bell-type entanglement with a holographic multimode atomic-ensemble-based quantum memory. The retrieved biphoton entanglement violates Bell's inequality for 1 microsecond storage time and a memory-process fidelity of 98% is demonstrated by quantum state tomography.
@article{arxiv.1204.1532,
title = {Holographic Storage of Biphoton Entanglement},
author = {Han-Ning Dai and Han Zhang and Sheng-Jun Yang and Tian-Ming Zhao and Jun Rui and You-Jin Deng and Li Li and Nai-Le Liu and Shuai Chen and Xiao-Hui Bao and Xian-Min Jin and Bo Zhao and Jian-Wei Pan},
journal= {arXiv preprint arXiv:1204.1532},
year = {2012}
}