title: A universal quantum information processor for scalable quantum communication and networks.
abstract: Entanglement provides an essential resource for quantum computation, quantum communication, and quantum networks. How to conveniently and efficiently realize the generation, distribution, storage, retrieval, and control of multipartite entanglement is the basic requirement for realistic quantum information processing. Here, we present a theoretical proposal to efficiently and conveniently achieve a universal quantum information processor (QIP) via atomic coherence in an atomic ensemble. The atomic coherence, produced through electromagnetically induced transparency (EIT) in the Λ-type configuration, acts as the QIP and has full functions of quantum beam splitter, quantum frequency converter, quantum entangler, and quantum repeater. By employing EIT-based nondegenerate four-wave mixing processes, the generation, exchange, distribution, and manipulation of light-light, atom-light, and atom-atom multipartite entanglement can be efficiently and flexibly achieved in a deterministic way with only coherent light fields. This method greatly facilitates the operations in quantum information processing, and holds promising applications in realistic scalable quantum communication and quantum networks.
authors.affiliation: Department of Physics, Shanghai University, Shanghai 200444, China.
authors.forename: Xihua
authors.initials: X
authors.lastname: Yang
authors.affiliation: Department of Physics, Shanghai University, Shanghai 200444, China.
authors.forename: Bolin
authors.initials: B
authors.lastname: Xue
authors.affiliation: State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, China.
authors.forename: Junxiang
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Beijing Computational Science Research Center, Beijing 100084, China.
authors.forename: Shiyao
authors.initials: S
authors.lastname: Zhu