Bright single-photon sources in bottom-up tailored nanowires

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.

Mapping the directional emission of quasi-two-dimensional photonic crystals of semiconductor nanowires using Fourier microscopy

“…This property has opened new opportunities to design a large variety of heterostructures. Some examples of these structures are wrapped-around quantum wells, 16,17 superlattices, 18,19 quantum dots embedded in nanowires showing single-photon emission, [20][21][22][23] and zincblende-wurtzite phase homostructures. 24,25 Furthermore, it is possible to grow III-V semiconductor nanowires on top of silicon substrates, combining the high-end properties of III-V material with well-developed and cheap silicon technology.…”

Quantum dot spontaneous emission control in a ridge waveguide

“…24,25 Since then, InP nanowire antennas embedding an InAsP QD have also been obtained by direct growth. 26 This approach ensures that a single emitter is located exactly on the wire axis, but also potentially changes the nature of the QD dipole. In the InAsP/InP system, a pronounced SE inhibition was observed in thin wires, 18 strongly supporting a transverse dipole orientation.…”

Single pairs of time-bin-entangled photons

“…A recent approach is to create polarizationentangled photons in a [111]-grown quantum dot embedded in a nanowire [47,48], where the cylindric symmetry reduces the fine-structure splitting [49]. The nanowire shape additionally offers high brightness [50] and coherent emission [47], as well as a directional Gaussian emission profile [51].…”