  Semiconductor devices are strong competitors in the race for the development
of quantum com-putational systems. In this work, we interface two semiconductor
building blocks of different di-mensionality and with complementary properties:
(1) a quantum dot hosting a single exciton andacting as a nearly ideal
single-photon emitter and (2) a quantum well in a 2D microcavity sustain-ing
polaritons, which are known for their strong interactions and unique
hydrodynamics propertiesincluding ultrafast real-time monitoring of their
propagation and phase-mapping. In the presentexperiment we can thus observe how
the injected single particles propagate and evolve inside themicrocavity,
giving rise to hydrodynamics features typical of macroscopic systems despite
their in-trinsic genuine quantum nature. In the presence of a structural
defect, we observe the celebratedquantum interference of a single particle that
produces fringes reminiscent of a wave propagation.While this behaviour could
be theoretically expected, our imaging of such an interference pattern,together
with a measurement of antibunching, constitutes the first demonstration of
spatial mappingof the self-interference of a single quantum particle hitting an
obstacle.
