title: Faithful entanglement swapping based on sum-frequency generation.
abstract: We show that an entanglement swapping operation performed with spontaneous parametric down-conversion can be made faithful without postselection using sum-frequency generation. This invites us to revisit the sum-frequency process and from a proof-of-principle experiment, we demonstrate that it provides a realistic solution for nonlinear optics at the single-photon level. This opens the way to attractive alternatives to six-photon protocols based on linear optics used, e.g., for the heralded creation of maximally entangled pairs or for device-independent quantum key distribution.
authors.affiliation: Group of Applied Physics, University of Geneva, 1211 Geneva 4, Switzerland.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Sangouard
authors.forename: Bruno
authors.initials: B
authors.lastname: Sanguinetti
authors.forename: Noé
authors.initials: N
authors.lastname: Curtz
authors.forename: Nicolas
authors.initials: N
authors.lastname: Gisin
authors.forename: Rob
authors.initials: R
authors.lastname: Thew
authors.forename: Hugo
authors.initials: H
authors.lastname: Zbinden