  A BosonSampling device is a quantum machine expected to perform tasks
intractable for a classical computer, yet requiring minimal non-classical
resources as compared to full-scale quantum computers. Photonic implementations
to date employed sources based on inefficient processes that only simulate
heralded single-photon statistics when strongly reducing emission
probabilities. BosonSampling with only single-photon input has thus never been
realised. Here, we report on a BosonSampling device operated with a bright
solid-state source of single-photon Fock states with high photon-number purity:
the emission from an efficient and deterministic quantum dot-micropillar system
is demultiplexed into three partially-indistinguishable single-photons, with a
single-photon purity $1{-}g^{(2)}(0)$ of $0.990{\pm}0.001$, interfering in a
linear optics network. Our demultiplexed source is between one and two
orders-of-magnitude more efficient than current heralded multi-photon sources
based on spontaneous parametric downconversion, allowing us to complete the
BosonSampling experiment faster than previous equivalent implementations.
