Efficient polarization-entangled photon generation using two-period PPLN waveguides

Yun-Kun Jiang, Akihisa Tomita

Tadashi Kishimoto

Tomohiro Yamazaki, Rikizo Ikuta, Toshiki Kobayashi +5 more

Yun-Kun Jiang, Akihisa Tomita

We report the generation of polarization-entangled photon pairs at all telecom band using two PPLN waveguides in a fiber loop. The visibility is about 92% in our measurement. Phase is stable for the entangled state.

Yi‐Wen Huang, Juan Feng, Yuanhua Li +4 more

Here, we demonstrate the generation and manipulation of hyperentanglement in polarization and time-energy degrees of freedom. The hyperentangled photon pairs are generated by cascaded second-harmonic generation and spontaneous parametric down-conversion processes in a high-efficiency periodically poled lithium niobate (PPLN) waveguide in a fiber Sagnac loop. The states achieve the maximum value of Clauser-Horne-Shimony-Holt Bell inequality of $S=2.76\ifmmode\pm\else\textpm\fi{}0.03$ with two-photon interference visibility of higher than 99% for polarization entanglement and the Franson-type two-photon interference visibility of 98.5% for time-energy entanglement. In addition, the polarization maximally entangled states can be fast switched to each other by using a PPLN on insulator chip through the electro-optic effect. After the entanglement manipulation, the two-photon interference visibility for polarization entanglement is still higher than 97% while keeping the quantum characteristics of time-energy degrees of freedom maintained. Our system paves a way toward reducing the complexity of quantum systems and has potential applications in many quantum-information tasks like fast superdense coding and teleportation.

Bienvenu I. Ndagano, Ruaridh Smith, Lewis D. Wright +5 more

We demonstrate a source of polarization-entangled photons based on periodically poled lithium niobate waveguides that produces pairs of entangled photons at a rate of 1.25 gigahertz and a CHSH entanglement parameter of 2.73.