title: High-efficiency frequency conversion in the single-photon regime.
abstract: In this Letter we demonstrate frequency conversion in the single-photon regime through Bragg-scattering four-wave mixing with near-unit efficiency in a 750 m long commercially available dispersion-engineered highly nonlinear fiber, where all photons and pump laser frequencies are in the low-loss telecommunications band. We achieve 99.1%±4.9% downconversion and 98.0%±5.0% upconversion of photons by 12 nm using a weak coherent state with an average input of 0.27 photons per detection gate window.
authors.affiliation: Centre for Ultrahigh bandwidth Devices for Optical Systems, Institute of Photonics and Optical Science, School of Physics, University of Sydney, Sydney, New South Wales, Australia. a.clark@physics.usyd.edu.au
authors.forename: Alex S
authors.initials: AS
authors.lastname: Clark
authors.forename: Shayan
authors.initials: S
authors.lastname: Shahnia
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Collins
authors.forename: Chunle
authors.initials: C
authors.lastname: Xiong
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Eggleton