title: Highly efficient frequency conversion with bandwidth compression of quantum light.
abstract: Hybrid quantum networks rely on efficient interfacing of dissimilar quantum nodes, as elements based on parametric downconversion sources, quantum dots, colour centres or atoms are fundamentally different in their frequencies and bandwidths. Although pulse manipulation has been demonstrated in very different systems, to date no interface exists that provides both an efficient bandwidth compression and a substantial frequency translation at the same time. Here we demonstrate an engineered sum-frequency-conversion process in lithium niobate that achieves both goals. We convert pure photons at telecom wavelengths to the visible range while compressing the bandwidth by a factor of 7.47 under preservation of non-classical photon-number statistics. We achieve internal conversion efficiencies of 61.5%, significantly outperforming spectral filtering for bandwidth compression. Our system thus makes the connection between previously incompatible quantum systems as a step towards usable quantum networks.
authors.affiliation: Integrated Quantum Optics, Applied Physics, University of Paderborn, Paderborn 33098, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Allgaier
authors.affiliation: Integrated Quantum Optics, Applied Physics, University of Paderborn, Paderborn 33098, Germany.
authors.forename: Vahid
authors.initials: V
authors.lastname: Ansari
authors.affiliation: Integrated Quantum Optics, Applied Physics, University of Paderborn, Paderborn 33098, Germany.
authors.forename: Linda
authors.initials: L
authors.lastname: Sansoni
authors.affiliation: Integrated Quantum Optics, Applied Physics, University of Paderborn, Paderborn 33098, Germany.
authors.forename: Christof
authors.initials: C
authors.lastname: Eigner
authors.affiliation: Integrated Quantum Optics, Applied Physics, University of Paderborn, Paderborn 33098, Germany.
authors.forename: Viktor
authors.initials: V
authors.lastname: Quiring
authors.affiliation: Integrated Quantum Optics, Applied Physics, University of Paderborn, Paderborn 33098, Germany.
authors.forename: Raimund
authors.initials: R
authors.lastname: Ricken
authors.affiliation: Integrated Quantum Optics, Applied Physics, University of Paderborn, Paderborn 33098, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Harder
authors.affiliation: Integrated Quantum Optics, Applied Physics, University of Paderborn, Paderborn 33098, Germany.|Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Brecht
authors.affiliation: Integrated Quantum Optics, Applied Physics, University of Paderborn, Paderborn 33098, Germany.
authors.forename: Christine
authors.initials: C
authors.lastname: Silberhorn