title: Generation of highly stable WDM time-bin entanglement by cascaded sum-frequency generation and spontaneous parametric downconversion in a PPLN waveguide device.
abstract: In this paper we report the generation of wavelength-division-multiplexed, time-bin entangled photon pairs by using cascaded optical second nonlinearities (sum-frequency generation and subsequent spontaneous parametric downconversion) in a periodically poled LiNbO3device. Visibilities of approximately 94% were clearly observed in two-photon interference experiments for all the wavelength-multiplexed channels under investigation (five pairs), with insensitivity to the polarization states of the photon pairs. We also evaluated the performances in terms of quantum-key-distribution (QKD) applications by using four single-photon detectors, which enables to evaluate the QKD performance properly. The results showed long-term stability over 70 hours, maintaining approximately 3% of the quantum error rate and 110 bit/s of the sifted key rate.
authors.forename: Shin
authors.initials: S
authors.lastname: Arahira
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Murai
authors.forename: Hironori
authors.initials: H
authors.lastname: Sasaki