  Boson-sampling has been presented as a simplified model for linear optical
quantum computing. In the boson-sampling model, Fock states are passed through
a linear optics network and sampled via number-resolved photodetection. It has
been shown that this sampling problem likely cannot be efficiently classically
simulated. This raises the question as to whether there are other quantum
states of light for which the equivalent sampling problem is also
computationally hard. We present evidence, without using a full complexity
proof, that a very broad class of quantum states of light --- arbitrary
superpositions of two or more coherent states --- when evolved via passive
linear optics and sampled with number-resolved photodetection, likely
implements a classically hard sampling problem.
