title: Modified E91 protocol demonstration with hybrid entanglement photon source.
abstract: We report on an experimental demonstration of the modified Ekert 91 protocol of quantum key distribution using a hybrid entanglement source with two different degrees of freedoms, a 1550 nm time-bin qubit and 810 nm polarization qubit. The violation of the Clauser-Horne-Shimony-Holt inequality could be demonstrated for the entanglement between the polarization qubit in free space and the time-bin qubit through 20 km fiber transmission. The secure key rate in our system is estimated 70-150 bps.
authors.forename: Mikio
authors.initials: M
authors.lastname: Fujiwara
authors.forename: Ken-ichiro
authors.initials: K
authors.lastname: Yoshino
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Nambu
authors.forename: Taro
authors.initials: T
authors.lastname: Yamashita
authors.forename: Shigehito
authors.initials: S
authors.lastname: Miki
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Terai
authors.forename: Zhen
authors.initials: Z
authors.lastname: Wang
authors.forename: Morio
authors.initials: M
authors.lastname: Toyoshima
authors.forename: Akihisa
authors.initials: A
authors.lastname: Tomita
authors.forename: Masahide
authors.initials: M
authors.lastname: Sasaki