title: Phase-stable source of polarization-entangled photons in a linear double-pass configuration.
abstract: We demonstrate a compact, robust, and highly efficient source of polarization-entangled photons, based on linear bi-directional down-conversion in a novel 'folded sandwich' configuration. Bi-directionally pumping a single periodically poled KTiOPO(4) (ppKTP) crystal with a 405-nm laser diode, we generate entangled photon pairs at the non-degenerate wavelengths 784 nm (signal) and 839 nm (idler), and achieve an unprecedented detection rate of 11.8 kcps for 10.4 μW of pump power (1.1 million pairs / mW), in a 2.9-nm bandwidth, while maintaining a very high two-photon entanglement quality, with a Bell-state fidelity of 99.3 ± 0.3%.
authors.affiliation: ICFO-Institut de Ciencies Fotoniques, 08860 Castelldefels, Barcelona, Spain. fabian.steinlechner@icfo.eu
authors.forename: Fabian
authors.initials: F
authors.lastname: Steinlechner
authors.forename: Sven
authors.initials: S
authors.lastname: Ramelow
authors.forename: Marc
authors.initials: M
authors.lastname: Jofre
authors.forename: Marta
authors.initials: M
authors.lastname: Gilaberte
authors.forename: Thomas
authors.initials: T
authors.lastname: Jennewein
authors.forename: Juan P
authors.initials: JP
authors.lastname: Torres
authors.forename: Morgan W
authors.initials: MW
authors.lastname: Mitchell
authors.forename: Valerio
authors.initials: V
authors.lastname: Pruneri
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D053844:Lasers, Solid-State; D008027:Light; D016014:Linear Models; D017785:Photons; D012031:Refractometry / Q000295:instrumentation*; D020349:Surface Plasmon Resonance / Q000295:instrumentation*