  Boson-sampling is a simplified model for quantum computing that may hold the
key to implementing the first ever post-classical quantum computer.
Boson-sampling is a non-universal quantum computer that is significantly more
straightforward to build than any universal quantum computer proposed so far.
We begin this chapter by motivating boson-sampling and discussing the history
of linear optics quantum computing. We then summarize the boson-sampling
formalism, discuss what a sampling problem is, explain why boson-sampling is
easier than linear optics quantum computing, and discuss the Extended
Church-Turing thesis. Next, sampling with other classes of quantum optical
states is analyzed. Finally, we discuss the feasibility of building a
boson-sampling device using existing technology.
