Photon doughnut-shaped pair for easy production of entangled photon pairs

Hsin Pin Lo, Atsushi Yabushita, Takayoshi Kobayashi

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Parametric down-conversion in a nonlinear crystal-generated photon pair in which photons have orthogonal polarization. The pair was emitted in a cone shape for each polarization and collimated by a lens to be doughnut shaped. The doughnutlike photon pair runs collinear to the pump laser. The group delay and walk-off between the orthogonal polarization photons in the pair were compensated passing through a half-wave plate and a nonlinear crystal. Then, the photon doughnut pair was coupled into a 1×2 fiber together with a pump laser, i.e., the intense pump laser was used as a guide for alignment. After the alignment was finished, a cut filter was inserted in the optical path to cut the pump laser transmitting the photon doughnut pair. The coincidence measurement of the output of the 1×2 fiber showed that the photon pairs are entangled in polarization.

Original languageEnglish
Article number062327
Number of pages4
JournalPhysical Review A - Atomic, Molecular, and Optical Physics
Issue number6
StatePublished - 29 Jun 2015


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