Bright single-photon sources in bottom-up tailored nanowires.

Reimer, Michael E; Bulgarini, Gabriele; Akopian, Nika; Hocevar, Moïra; Bavinck, Maaike Bouwes; Verheijen, Marcel A; Bakkers, Erik P A M; Kouwenhoven, Leo P et al. · Nat Commun · 2012

basic_science · Level V

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Abstract

The ability to achieve near-unity light-extraction efficiency is necessary for a truly deterministic single-photon source. The most promising method to reach such high efficiencies is based on embedding single-photon emitters in tapered photonic waveguides defined by top-down etching techniques. However, light-extraction efficiencies in current top-down approaches are limited by fabrication imperfections and etching-induced defects. The efficiency is further tempered by randomly positioned off-axis quantum emitters. Here we present perfectly positioned single quantum dots on the axis of a tailored nanowire waveguide using bottom-up growth. In comparison to quantum dots in nanowires without waveguides, we demonstrate a 24-fold enhancement in the single-photon flux, corresponding to a light-extraction efficiency of 42%. Such high efficiencies in one-dimensional nanowires are promising to transfer quantum information over large distances between remote stationary qubits using flying qubits within the same nanowire p-n junction.