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Nanophotonic quantum information processing systems require spatially ordered, spectrally uniform single photon sources (SPSs) integrated on-chip with co-designed light manipulating elements providing emission rate enhancement, emitted photon guidance, and lossless propagation. Towards this goal, we consider systems comprising an SPS array with each SPS coupled to a dielectric building block (DBB) based multifunctional light manipulation unit (LMU). For the SPS array, we report triggered single photon emission from GaAs (001)

Realization of quantum optical circuits is at the heart of quantum photonic information processing. A long-standing obstacle, however, has been the absence of a suitable platform of single photon sources (SPSs). Such SPSs need to be in spatially ordered arrays and produce, on-demand, highly pure, and indistinguishable single photons with sufficiently uniform emission characteristics to enable controlled interference between photons from distinct sources underpinning functional quantum optical networks. We report on such a platform of SPSs based on a unique class of epitaxial quantum dots dubbed mesa-top single quantum dot. Under resonant excitation, the spatially ordered SPSs (without Purcell enhancement) show single photon purity of >99% [ g (2) (0) ~ 0.015], high two-photon Hong-Ou-Mandel interference visibilities of 0.82 ± 0.03 (at 11.5 kelvin, without cavity), and spectral nonuniformity of <3 nanometers, within established locally tunable technology. Our platform of SPSs paves the path to creating on-chip scalable quantum photonic networks for communication, computation, simulation, sensing and imaging.

Realizing ordered and spectrally uniform single photon source arrays integrable onchip with light manipulating elements in scalable architecture lies at the core of building monolithic quantum optical circuits (QOCs). We demonstrate here a spatially-ordered 5 × 8 array of surface-curvature driven mesa-top GaAs(001)/InGaAs/GaAs single quantum dots (MTSQDs) that exhibit highly pure (~99% ) single photon emission as deduced from the measured g (2) (0) < 0.02 at 9.4K. Polarization-independent and polarization-resolved high resolution photoluminescence (PL) measurements show that these ordered and spectrally uniform QDs have neutral exciton emission with intrinsic linewidth ~ 10 µeV and fine structure splitting < 10 µeV, an important figure of merit for the use of QDs in QOCs. The findings point to the high potential of such MTSQD based single photon source arrays as a promising platform for on-chip scalable integration with light manipulating units (connected resonant cavity, waveguide, beam splitter, etc.) to enable constructing QOCs.Realizing spatially ordered single photon sources that can be readily integrated with light manipulating elements in a scalable architecture has been a major goal towards realizing on-chip integrated quantum optical circuits 1-3 (QOCs) for applications in quantum communication and quantum information processing (QIP). A significant step towards this goal was recently taken with the demonstration of 5×8 array of a new class of semiconductor single quantum dots that form on the top of laterally confined mesas with unprecedented control on shape and size 4-6 . These mesa-top single quantum dots (MTSQDs) are formed by site-selective size-reducing epitaxy on nanomesas fabricated with specifically chosen edge orientations that induce directedmigration of atoms symmetrically from the sidewalls to the mesa top ( Fig. 1(a)) during growth, thus ensuring spatially-selective growth on mesa top 4-6 ( Fig.1(b)). The approach is thus dubbed substrate-encoded size-reducing epitaxy (SESRE) 7-9 . The synthesized GaAs(001)/In0.5Ga0.5As/GaAs MTSQDs ( Fig. 1(b)) being reported on here were shown to be efficient single photon emitters at 10K with g (2) (0) ~0.15 and maintain reasonable single photon emission (g (2) (0) ~0.3) up to liquid nitrogen temperature 5,6 . The emission wavelength from every MTSQD in the 5×8 array is shown in Fig.1(c). These MTSQDs are formed with considerable control on size and shape and thus, as grown, exhibit highly uniform PL emission with a standard deviation of ~8 nm, much better than the commonly employed lattice mismatch strain-driven spontaneously formed 3D island quantum dots dubbed self-assembled quantum dots (SAQDs) 5,6 .The above noted PL and the encouraging g (2) (τ) behavior were, however, limited by the instrument resolution of ~300 μeV. The true nature and potential of this new class of epitaxial single QDs (SQDs) was thus not revealed 5 . Strikingly, these studies revealed the presence of pairs of as-grown MTSQDs (marked by like-color circles in Fig. 1(c)) with emis...

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