title: Generation of 1.5 μm discrete frequency-entangled two-photon state in polarization-maintaining fibers.
abstract: In this Letter, the generation of a 1.5 μm discrete frequency-entangled two-photon state is realized based on a piece of commercial polarization-maintaining fiber (PMF). It is connected with a polarization beam splitter to realize a modified Sagnac fiber loop (MSFL). Correlated two-photon states are generated through a spontaneous four-wave-mixing process along the two propagation directions of the MSFL, and output from the MSFL with orthogonal polarizations. Their quantum interference is realized through a 45° polarization collimation between polarization axes of PMFs inside and outside the MSFL, while their phase difference is controlled by the polarization state of the pump light. The frequency-entangled property of the two-photon state is demonstrated by a spatial quantum beating experiment with a fringe visibility of 98.2±1.3%, without subtracting the accidental coincidence counts. The proposed scheme generates a 1.5 μm discrete frequency-entangled two-photon state in a polarization-maintaining way, which is desired in practical quantum light sources.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhou
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Chenzhi
authors.initials: C
authors.lastname: Yuan
authors.forename: Yidong
authors.initials: Y
authors.lastname: Huang
authors.forename: Jiangde
authors.initials: J
authors.lastname: Peng