Generation of narrow-band polarization-entangled photon pairs for atomic quantum memories.
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.
Bao
Xiao-Hui
XH
Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China.
Qian
Yong
Y
Yang
Jian
J
Zhang
Han
H
Chen
Zeng-Bing
ZB
Yang
Tao
T
Pan
Jian-Wei
JW