title: Three-color Sagnac source of polarization-entangled photon pairs.
abstract: We demonstrate a compact and stable source of polarization-entangled pairs of photons, one at 810 nm wavelength for high detection efficiency and the other at 1550 nm for long-distance fiber communication networks. Due to a novel Sagnac-based design of the interferometer no active stabilization is needed. Using only one 30 mm ppKTP bulk crystal the source produces photons with a spectral brightness of 1.13 x 10(6) pairs/s/mW/THz with an entanglement fidelity of 98.2%. Both photons are single-mode fiber coupled and ready to be used in quantum key distribution (QKD) or transmission of photonic quantum states over large distances.
authors.affiliation: Institute for Quantum Optics and Quantum Information - IQOQI, Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria. michael.hentschel@ait.ac.at
authors.forename: Michael
authors.initials: M
authors.lastname: Hentschel
authors.forename: Hannes
authors.initials: H
authors.lastname: Hübel
authors.forename: Andreas
authors.initials: A
authors.lastname: Poppe
authors.forename: Anton
authors.initials: A
authors.lastname: Zeilinger
mesh_terms: D003116:Color; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008029:Lighting / Q000295:instrumentation* / Q000379:methods*; D017785:Photons