title: Downconversion quantum interface for a single quantum dot spin and 1550-nm single-photon channel.
abstract: Long-distance quantum communication networks require appropriate interfaces between matter qubit-based nodes and low-loss photonic quantum channels. We implement a downconversion quantum interface, where the single photons emitted from a semiconductor quantum dot at 910 nm are downconverted to 1560 nm using a fiber-coupled periodically poled lithium niobate waveguide and a 2.2-μm pulsed pump laser. The single-photon character of the quantum dot emission is preserved during the downconversion process: we measure a cross-correlation g(2)(τ = 0) = 0.17 using resonant excitation of the quantum dot. We show that the downconversion interface is fully compatible with coherent optical control of the quantum dot electron spin through the observation of Rabi oscillations in the downconverted photon counts. These results represent a critical step towards a long-distance hybrid quantum network in which subsystems operating at different wavelengths are connected through quantum frequency conversion devices and 1.5-μm quantum channels.
authors.affiliation: E L Ginzton Laboratory, Stanford University, Stanford, California, USA. jason.pelc@hp.com
authors.forename: Jason S
authors.initials: JS
authors.lastname: Pelc
authors.forename: Leo
authors.initials: L
authors.lastname: Yu
authors.forename: Kristiaan
authors.initials: K
authors.lastname: De Greve
authors.forename: Peter L
authors.initials: PL
authors.lastname: McMahon
authors.forename: Chandra M
authors.initials: CM
authors.lastname: Natarajan
authors.forename: Vahid
authors.initials: V
authors.lastname: Esfandyarpour
authors.forename: Sebastian
authors.initials: S
authors.lastname: Maier
authors.forename: Christian
authors.initials: C
authors.lastname: Schneider
authors.forename: Martin
authors.initials: M
authors.lastname: Kamp
authors.forename: Sven
authors.initials: S
authors.lastname: Höfling
authors.forename: Robert H
authors.initials: RH
authors.lastname: Hadfield
authors.forename: Alfred
authors.initials: A
authors.lastname: Forchel
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: M M
authors.initials: MM
authors.lastname: Fejer
mesh_terms: D004574:Electromagnetic Fields; D004581:Electronics / Q000379:methods; D007834:Lasers; D009556:Niobium / Q000737:chemistry; D010087:Oxides / Q000737:chemistry; D017785:Photons; D045663:Quantum Dots; D013685:Telecommunications / Q000295:instrumentation*
chemical_list: D010087:Oxides; D009556:Niobium; C091692:lithium niobate