title: Generation of narrow-band polarization-entangled photon pairs for atomic quantum memories.
abstract: We report an experimental realization of a narrow band polarization-entangled photon source with a linewidth of 9.6 MHz through cavity-enhanced spontaneous parametric down-conversion. This linewidth is comparable to the typical linewidth of atomic ensemble-based quantum memories. Single-mode output is realized by setting a reasonable cavity length difference between different polarizations, using of temperature controlled etalons and actively stabilizing the cavity. The entangled property is characterized with quantum state tomography, giving a fidelity of 94% between our state and a maximally entangled state. The coherence length is directly measured to be 32 m through two-photon interference.
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China.
authors.forename: Xiao-Hui
authors.initials: XH
authors.lastname: Bao
authors.forename: Yong
authors.initials: Y
authors.lastname: Qian
authors.forename: Jian
authors.initials: J
authors.lastname: Yang
authors.forename: Han
authors.initials: H
authors.lastname: Zhang
authors.forename: Zeng-Bing
authors.initials: ZB
authors.lastname: Chen
authors.forename: Tao
authors.initials: T
authors.lastname: Yang
authors.forename: Jian-Wei
authors.initials: JW
authors.lastname: Pan