title: An optimized photon pair source for quantum circuits.
abstract: We implement an ultrafast pulsed type-II parametric down conversion source in a periodically poled KTP waveguide at telecommunication wavelengths with almost identical properties between signal and idler. As such, our source resembles closely a pure, genuine single mode photon pair source with indistinguishable modes. We measure the joint spectral intensity distribution and second order correlation functions of the marginal beams and find with both methods very low effective mode numbers corresponding to a Schmidt number below 1.16. We further demonstrate the indistinguishability as well as the purity of signal and idler photons by Hong-Ou-Mandel interferences between signal and idler and between signal/idler and a coherent field, respectively. Without using narrowband spectral filtering, we achieve a visibility for the interference between signal and idler of 94.8% and determine a purity of more than 80% for the heralded single photon states. Moreover, we measure raw heralding efficiencies of 20.5% and 15.5% for the signal and idler beams corresponding to detector-loss corrected values of 80% and 70%.
authors.affiliation: Applied Physics, University of Paderborn, Warburger Strasse 100, 33098 Paderborn, Germany. georg.harder@uni-paderborn.de
authors.forename: Georg
authors.initials: G
authors.lastname: Harder
authors.forename: Vahid
authors.initials: V
authors.lastname: Ansari
authors.forename: Benjamin
authors.initials: B
authors.lastname: Brecht
authors.forename: Thomas
authors.initials: T
authors.lastname: Dirmeier
authors.forename: Christoph
authors.initials: C
authors.lastname: Marquardt
authors.forename: Christine
authors.initials: C
authors.lastname: Silberhorn
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D008027:Light; D008029:Lighting / Q000295:instrumentation*; D017785:Photons; D011789:Quantum Theory; D012542:Scattering, Radiation; D020349:Surface Plasmon Resonance / Q000295:instrumentation*; D013685:Telecommunications / Q000295:instrumentation*