title: On-chip low loss heralded source of pure single photons.
abstract: A key obstacle to the experimental realization of many photonic quantum-enhanced technologies is the lack of low-loss sources of single photons in pure quantum states. We demonstrate a promising solution: generation of heralded single photons in a silica photonic chip by spontaneous four-wave mixing. A heralding efficiency of 40%, corresponding to a preparation efficiency of 80% accounting for detector performance, is achieved due to efficient coupling of the low-loss source to optical fibers. A single photon purity of 0.86 is measured from the source number statistics without narrow spectral filtering, and confirmed by direct measurement of the joint spectral intensity. We calculate that similar high-heralded-purity output can be obtained from visible to telecom spectral regions using this approach. On-chip silica sources can have immediate application in a wide range of single-photon quantum optics applications which employ silica photonics.
authors.affiliation: Clarendon Laboratory, University of Oxford, Oxford, United Kingdom.
authors.forename: Justin B
authors.initials: JB
authors.lastname: Spring
authors.forename: Patrick S
authors.initials: PS
authors.lastname: Salter
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Metcalf
authors.forename: Peter C
authors.initials: PC
authors.lastname: Humphreys
authors.forename: Merritt
authors.initials: M
authors.lastname: Moore
authors.forename: Nicholas
authors.initials: N
authors.lastname: Thomas-Peter
authors.forename: Marco
authors.initials: M
authors.lastname: Barbieri
authors.forename: Xian-Min
authors.initials: XM
authors.lastname: Jin
authors.forename: Nathan K
authors.initials: NK
authors.lastname: Langford
authors.forename: W Steven
authors.initials: WS
authors.lastname: Kolthammer
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Booth
authors.forename: Ian A
authors.initials: IA
authors.lastname: Walmsley