  Modern quantum technologies have matured such that they can now be used in
space applications, e.g., long-distance quantum communication. Here, we present
the design of a compact true single photon source that can enhance the secure
data rates in satellite-based quantum key distribution scenarios compared to
conventional laser-based light sources. Our quantum light source is a
fluorescent color center in hexagonal boron nitride. The emitter is
off-resonantly excited by a diode laser and directly coupled to an integrated
photonic processor that routes the photons to different experiments performed
directly on-chip: (i) the characterization of the single photon source and (ii)
testing a fundamental postulate of quantum mechanics, namely the relation of
the probability density and the wave function (known as Born's rule). The
described payload is currently being integrated into a 3U CubeSat and scheduled
for launch in 2024 into low Earth orbit. We can therefore evaluate the
feasibility of true single photon sources and reconfigurable photonic circuits
in space. This provides a promising route toward a high-speed quantum network.
