![]() In the top-down approach, a wafer with epitaxial QDs is etched with the exception of nanoscale local areas that include only one or several QDs and form one-dimensional NW-like structures. There are two opposite approaches to the fabrication of NW-QDs: top-down and bottom-up. After embedding a QD in a nanowire (NW), the efficiency of light extraction can theoretically approach 100%. Moreover, it has been expected as a promising building block for future nanoscale electronic and photonic devices owing to its high crystalline quality and integration possibility. Photonic wire is advantageous in offering a broadband high collection efficiency and could be applied to spectrally feasible single-photon and entangled photon pairs. Microcavity is an efficient way to build an interface for photon-QD quantum electrodynamics, but the linewidth of the cavity mode is often too narrow to interact with both the exciton and the biexciton of QD, which challenges the collection of high-rate entangled photon pairs. For example, the QD-micropillar system has been reported as a promising single-photon source that combines features of high efficiency and near-perfect levels of purity and indistinguishably. The coupling of a single QD to a confined optical mode of microcavity increases the light-matter interaction, leading to a fast spontaneous emission of QD (the Purcell effect) and the appearance of light-matter-coupled dress states in the strong coupling regime. ![]() The most successful approach is inserting the QD into a photonic structure, either a microcavity or a photonic wire. brightness), in the last few years, several approaches have been pursued. To reduce their all-space emission and enhance their unit-directional emission and collection (i.e. Self-assembled nanowires, quantum dots, single photon emitters, molecular beam epitaxy INTRODUCTIONĮpitaxial self-assembled III–V quantum dots (QDs), so-called ‘artificial atoms’, are of particular interest for single-photon emission, owing to their stability, narrow spectral linewidth and short radiative lifetime.
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