Highly pure single photon emission from spectrally uniform surface-curvature directed mesa top single quantum dot ordered array

Abstract

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...

Planarized spatially-regular arrays of spectrally uniform single quantum dots as on-chip single photon sources for quantum optical circuits

“…However, controlling simultaneously the spatial and spectral uniformity adequately for either the dominantly explored semiconductor QD --the 3D island QD-or defect-based SPSs is still a great challenge 2,8,11 . In this paper we report: (a) the realization of a new class of semiconductor mesa top single quantum dots (MTSQDs) [12][13][14] in arrays (Fig. 1(a)) whose single photon emission purity is ~ 99.5% at 18K and as-grown spectral uniformity is < 2nm across a 5×8 array distributed over 1000μm 2 (Fig.…”

Quantum Antennas

“…The analysis of the recent technological achievements shows that the novel procedures to overcome these limitations have been proposed and high‐quality antenna arrays covering large areas have been fabricated. [ 264–266 ]…”

“…For the single photon sources array, it was reported about the triggered single‐photon emission from GaAs(001)/InGaAs single QDs grown selectively on the top of nanomesas using the approach of substrate‐encoded size‐reducing epitaxy (see Figure 18c). [ 265 ] As it was shown, it satisfies such an important requirement as the on‐chip integrability with a multifunctional light unit, comprising an antenna, a waveguide, a cavity, a beam splitter, etc.…”

Nanoscale Positioning Approaches for Integrating Single Solid‐State Quantum Emitters with Photonic Nanostructures

“…However, the optical properties of these so‐called site‐controlled QDs usually suffer from the defects in the etched surfaces induced during the substrate patterning process, [ 10,11 ] though it should be noted that promising results with respect to homogeneity (between quantum dots) and single‐photon purity and coherence have been reported. [ 12,13 ] Heterogenous integration, via pick‐and‐place techniques of QDs in nanowires, for example, is an exciting and yet technically demanding path for combining the strengths of different materials platforms. Progress along this line was recently summarized in two review articles [ 14,15 ] and will not be discussed further.…”