title: Cavity-Enhanced and Ultrafast Superconducting Single-Photon Detectors.
abstract: Ultrafast single-photon detectors with high efficiency are of utmost importance for many applications in the context of integrated quantum photonic circuits. Detectors based on superconductor nanowires attached to optical waveguides are particularly appealing for this purpose. However, their speed is limited because the required high absorption efficiency necessitates long nanowires deposited on top of the waveguide. This enhances the kinetic inductance and makes the detectors slow. Here, we solve this problem by aligning the nanowire, contrary to usual choice, perpendicular to the waveguide to realize devices with a length below 1 μm. By integrating the nanowire into a photonic crystal cavity, we recover high absorption efficiency, thus enhancing the detection efficiency by more than an order of magnitude. Our cavity enhanced superconducting nanowire detectors are fully embedded in silicon nanophotonic circuits and efficiently detect single photons at telecom wavelengths. The detectors possess subnanosecond decay (∼120 ps) and recovery times (∼510 ps) and thus show potential for GHz count rates at low timing jitter (∼32 ps). The small absorption volume allows efficient threshold multiphoton detection.
authors.affiliation: Institute of Nanotechnology (INT), Karlsruhe Institute of Technology , 76344 Eggenstein-Leopoldshafen, Germany.|Institute of Theoretical Solid State Physics (TFP), Karlsruhe Institute of Technology , 76131 Karlsruhe, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Vetter
authors.affiliation: Institute of Nanotechnology (INT), Karlsruhe Institute of Technology , 76344 Eggenstein-Leopoldshafen, Germany.|Institute of Physics, University of Münster , 48149 Münster, Germany.
authors.forename: Simone
authors.initials: S
authors.lastname: Ferrari
authors.affiliation: Institute of Nanotechnology (INT), Karlsruhe Institute of Technology , 76344 Eggenstein-Leopoldshafen, Germany.|Institute of Physics, University of Münster , 48149 Münster, Germany.
authors.forename: Patrik
authors.initials: P
authors.lastname: Rath
authors.affiliation: Institute of Theoretical Solid State Physics (TFP), Karlsruhe Institute of Technology , 76131 Karlsruhe, Germany.
authors.forename: Rasoul
authors.initials: R
authors.lastname: Alaee
authors.affiliation: Institute of Nanotechnology (INT), Karlsruhe Institute of Technology , 76344 Eggenstein-Leopoldshafen, Germany.|Institute of Physics, University of Münster , 48149 Münster, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Kahl
authors.affiliation: Institute of Nanotechnology (INT), Karlsruhe Institute of Technology , 76344 Eggenstein-Leopoldshafen, Germany.|Department of Physics, Moscow State Pedagogical University , Moscow 119992, Russia.
authors.forename: Vadim
authors.initials: V
authors.lastname: Kovalyuk
authors.affiliation: Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology , 76131 Karlsruhe, Germany.
authors.forename: Silvia
authors.initials: S
authors.lastname: Diewald
authors.affiliation: Department of Physics, Moscow State Pedagogical University , Moscow 119992, Russia.|National Research University Higher School of Economics , Moscow 101000, Russia.
authors.forename: Gregory N
authors.initials: GN
authors.lastname: Goltsman
authors.affiliation: Department of Physics, Moscow State Pedagogical University , Moscow 119992, Russia.|Moscow Institute of Physics and Technology (State University) , Moscow 141700, Russia.
authors.forename: Alexander
authors.initials: A
authors.lastname: Korneev
authors.affiliation: Institute of Nanotechnology (INT), Karlsruhe Institute of Technology , 76344 Eggenstein-Leopoldshafen, Germany.|Institute of Theoretical Solid State Physics (TFP), Karlsruhe Institute of Technology , 76131 Karlsruhe, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Rockstuhl
authors.affiliation: Institute of Nanotechnology (INT), Karlsruhe Institute of Technology , 76344 Eggenstein-Leopoldshafen, Germany.|Institute of Physics, University of Münster , 48149 Münster, Germany.
authors.forename: Wolfram H P
authors.initials: WH
authors.lastname: Pernice
keywords: Superconducting nanowire single-photon detector; multiphoton detection; nanophotonic circuit; photonic crystal cavity