  Quantum mechanics promises computational powers beyond the reach of classical
computers. Current technology is on the brink of an experimental demonstration
of the superior power of quantum computation compared to classical devices. For
such a demonstration to be meaningful, experimental noise must not affect the
computational power of the device; this occurs when a classical algorithm can
use the noise to simulate the quantum system.
  In this work, we demonstrate an algorithm which simulates boson sampling, a
quantum advantage demonstration based on many-body quantum interference of
indistinguishable bosons, in the presence of optical loss. Finding the level of
noise where this approximation becomes efficient lets us map out the maximum
level of imperfections at which it is still possible to demonstrate a quantum
advantage. We show that current photonic technology falls short of this
benchmark. These results call into question the suitability of boson sampling
as a quantum advantage demonstration.
