  Realization of the long sought on-chip scalable photonic quantum information
processing networks has been thwarted by the absence of spatially-ordered and
scalable on-demand single photon emitters with emission figures-of-merit
exceeding the required thresholds across large numbers. The positioning must
meet the required degree of accuracy that enables fabricating their
interconnection to create the desired functional network. Here we report on the
realization of large-area spatially-ordered arrays of mesa-top single quantum
dots (MTSQDs) that are demonstrated [1] to be on-demand single photon emitters
with characteristics that meet the requirements for implementing quantum
photonic circuits/platforms aimed at quantum key distribution, linear optical
quantum computing, simulations of quantum many-body problems, and
metrology/sensing. The reported GaAs/InGaAs/GaAs MTSQD arrays, grown via SESRE
(substrate-encoded size-reducing epitaxy) are in multiple arrays of up to
100x100 with 5um pitch, across a centimeter radius area. We show illustrative
large-area images of the emission intensity (brightness) and color-coded
wavelength distribution exhibiting ~3.35nm standard deviation. Scanning
transmission electron microscopy shows a remarkable control on the QD location
to within ~3nm accuracy laterally and ~1nm vertically. The primary remaining
challenge is the control on the uniformity of the currently wet-chemically
etched as-patterned nanomesa lateral size across the substrate, a surmountable
technical issue. Thus, SESRE offers the most promising approach to realizing
on-chip scalable spatially-ordered arrays of on-demand bright single quantum
emitters meeting the figures-of-merit required for on-chip fully integrated
quantum photonic circuit platforms-monolithic (such as based upon AlGaAs on
insulator) or hybrid that leverage the silicon-on-insulator (SOI) photonic
integrated circuit (PIC).
