title: Observation of strongly entangled photon pairs from a nanowire quantum dot.
abstract: A bright photon source that combines high-fidelity entanglement, on-demand generation, high extraction efficiency, directional and coherent emission, as well as position control at the nanoscale is required for implementing ambitious schemes in quantum information processing, such as that of a quantum repeater. Still, all of these properties have not yet been achieved in a single device. Semiconductor quantum dots embedded in nanowire waveguides potentially satisfy all of these requirements; however, although theoretically predicted, entanglement has not yet been demonstrated for a nanowire quantum dot. Here, we demonstrate a bright and coherent source of strongly entangled photon pairs from a position-controlled nanowire quantum dot with a fidelity as high as 0.859±0.006 and concurrence of 0.80±0.02. The two-photon quantum state is modified via the nanowire shape. Our new nanoscale entangled photon source can be integrated at desired positions in a quantum photonic circuit, single-electron devices and light-emitting diodes.
authors.affiliation: Quantum Transport, Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628CJ Delft, The Netherlands.
authors.forename: Marijn A M
authors.initials: MA
authors.lastname: Versteegh
authors.affiliation: Quantum Transport, Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628CJ Delft, The Netherlands.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Reimer
authors.affiliation: Quantum Transport, Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628CJ Delft, The Netherlands.
authors.forename: Klaus D
authors.initials: KD
authors.lastname: Jöns
authors.affiliation: National Research Council of Canada, Ottawa, Ontario, Canada K1A 0R6.
authors.forename: Dan
authors.initials: D
authors.lastname: Dalacu
authors.affiliation: National Research Council of Canada, Ottawa, Ontario, Canada K1A 0R6.
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Poole
authors.affiliation: Politecnico di Milano, Dipartimento di Elettronica Informazione e Bioingegneria, piazza Leonardo da Vinci 32, 20133 Milano, Italy.
authors.forename: Angelo
authors.initials: A
authors.lastname: Gulinatti
authors.affiliation: Micro Photon Devices, Via Stradivari 4, 39100 Bolzano, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Giudice
authors.affiliation: Quantum Transport, Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628CJ Delft, The Netherlands.
authors.forename: Val
authors.initials: V
authors.lastname: Zwiller