Browsing by Subject "photon pairs"

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    Distribution of entangled photon pairs over few-mode fibers
    (Nature Publishing group, 2017-11-12) Cui, Liang; Su, Jie; Li, Xiaoying; Ou, Z. Y.; Physics, School of Science
    Few-mode fibers (FMFs) have been recently employed in classical optical communication to increase the data transmission capacity. Here we explore the capability of employing FMF for long distance quantum communication. We experimentally distribute photon pairs in the forms of time-bin and polarization entanglement over a 1-km-long FMF. We find the time-bin entangled photon pairs maintain their high degree of entanglement, no matter what type of spatial modes they are distributed in. For the polarization entangled photon pairs, however, the degree of entanglement is maintained when photon pairs are distributed in LP 01 mode but significantly declines when photon pairs are distributed in LP 11 mode due to a mode coupling effect in LP 11 mode group. We propose and test a remedy to recover the high degree of entanglement. Our study shows, when FMFs are employed as quantum channels, selection of spatial channels and degrees of freedom of entanglement should be carefully considered.
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    Spectral study of photon pairs generated in dispersion shifted fiber with a pulsed pump
    (Optical Society of America, 2008-01-07) Li, Xiaoying; Ma, Xiaoxin; Ou, Zhe Yu; Yang, Lei; Cui, Liang; Yu, Daoyin; Physics, School of Science
    Spectral correlation of photon pairs generated in dispersion shifted fiber by a pulsed pump is theoretically analyzed and experimentally investigated. We first calculate the spectral function of photon pairs according to the deduced two-photon state generated by spontaneous four wave mixing under the assumptions close to the real experimental conditions. We then experimentally study the spectral property of the signal and idler photon pairs generated in optical fiber by photon correlation measurements, and the experimental results agree with the calculation. The investigation is useful for developing fiber-based sources of entangled photon pairs and for studying multi-photon quantum interference with multiple photon pairs.